3 2017 vakblad over betonconstructies fib Symposium 2017 Maastricht vakblad over betonconstructies fib Symposium 2017 Maastricht 3 2017 Dyckerhoff ?maakt er meer van. Dyckerhoff, Verkoopkantoor Nederland/Belgie nl@dyckerhoff.com www.dyckerhoff.nl Waalbrug Ewijk (A 50) Dyckerhoff Basal levert hoge sterkte beton C 90/105; Dyckerhoff levert speciale cement VARIODUR 30 Fotos: Bart van Hoek DyB Anz_Waalbrug Ewijk_225x297_lay.indd 1 15.03.17 10:33 Munterij 8, 4762 AH Zevenbergen ? Postbus 17, 4760 AA Zevenbergen ? T 0168 - 33 12 400 ? E info@bbtec.nl ? www.bbtectools.com/nl "Structural Anchoring Systems" voor Constructieve Veiligheid Voor Constructeurs, Architecten, Staalbouwers, Aannemers, etc. MET GRATIS DESIGNFIX ONDERSTEUNING NIEUW NIEUW Nieuwe Anker Design Software DesignFiX® gratis anker calculatie soft- ware voor B+BTec SAS en BIS anker syste- men. ? Complete invoer vrijheid en 3D interface ? Resultaten in één oogopslag ? Automatische berekening ef ectieve zetdiepte ? Geïntegreerde FEM berekening voor bepalen dikte voetplaat Nieuwe BIS Injectie Systemen Pure-Epoxy 3:1 voor ultra hoge lasten. ETA goedkeuring voor gescheurd en ongescheurd beton, diamant geboorde en watergevulde gaten. Seismische Goedkeuring C1 en C2. Voor de installatie van stek- en draadeinden. Vinylester voor hoge lasten. ETA goedkeuring voor ge- scheurd en ongescheurd beton en watergevulde gaten. Seismische Goedkeuring C1. Styreen vrij. Voor de installatie van stek- en draadeinden. Polyester voor gemiddelde lasten. ETA goedkeuring voor ongescheurd beton en holle steen. Styreen vrij. Voor de installatie van draadeinden. CEMENT_15_09.indd 1 14-09-15 13:29 TEKTONIEK.NL Kennis zit in mensen. Binnen het Tektoniek-netwerk beschikken we over de kennis voor de beste architectuur in beton. Daarbij gaat het altijd om de relatie tussen vorm - geving, constructie en maakbaarheid. Met expertise op het gebied van schoonbeton, constructieve optimalisaties, productontwikkelingen en materiaalontwikkelingen. Op de netwerkpagina van www.tektoniek.nl zijn de juiste mensen te vinden. Misschien hoort u er ook bij? Dat kan, het kennisnetwerk is groeiende. TEKTONIEK hoe maak ik de beste architectuur in beton? Drents Museum Assen - designed by Erick van Egeraat - foto: J. Collingr\ idge advertentie Tektoniek Cement 12016.indd 1 03-02-16 09:34 Partners1 Meer informatie over deze bedrijven en over het partnerschap staat op www.cementonline.nl/partners. partners 3 2017 Ce ntraal overleg Bouwconstruc ties fb Studievereniging b -N ederland Partners van Cement, kennisplatform betonconstructies Cement is een platform van én voor constructeurs. Het platform legt kennis vast over construeren met beton, en verspreidt deze onder vakgenoten. Om het belang hiervan te onderstrepen kan een bedrijf kennispartner van Cement worden. Een partner geniet een aantal voordelen, zoals een flinke korting op het abonnement en een profielpagina op Cementonline. Het partnerschap is voorbehouden aan bedrijven voor wie de kennis daadwerkelijk is bedoeld. Hebt u ook interesse om partner te worden, neem dan contact op met Jacques Linssen, j.linssen@aeneas.nl. 2 4 'Architecture is a misconception' Interview with Chris Poulissen, keynote speaker at the fib Symposium 8 Maputo-Katembe Bridge, Maputo Bay, Mozambique Jörn Seitz, Dean Gary Swanepoel, B. Pengyu 14 Koningin Máximabrug, Alphen aan den Rijn, The Netherlands André Bouman, Nick Nass 18 Amalia Bridge, Waddinxveen, The Netherlands Bas van den Berk 22 Approach bridge of the second Wuhu Yangtze River Highway Bridge, China Ke Hu, Zuqiao Ma, Xuefei Shi, Xin Ruan 26 Steel-concrete composite flat arch bridge, Northampton, United Kingdom Riccardo Stroscio 32 Kano River Crossing Bridge, Shizuoka Prefecture, Japan Yuki Kaminaga, Takeshi Nakagawa, Hiromi Hosono, Hidetoshi Ichikawa, Masanao Kajiura 38 Sarvsfossen Dam, Bykle, Norway Erlend Eithun Aasheim, Jan Lindemark, Audun Hanssen Lundberg, Morten Engen 42 Hendrik Bulthuis Aquaduct, Burgum, The Netherlands Sander van het Erve 48 Tunnel underneath highway A12, Ede, The Netherlands Stefan Schoenmakers, Erik de Rooij 52 Combined bypass railway and tangent road near station Mechelen, Belgium Bart De Pauw 58 Oosterweel Link, Antwerp, Belgium Frank Kaalberg, Okke Los, Jan Ruigrok, Richard Roggeveld, Gert Osselaer, Benoit Janssens 64 New sea lock Noordersluis, IJmuiden, The Netherlands Paul Wernsen, Leon Lous 68 UHPC pedestrian bridge, Eindhoven, The Netherlands Jan Falbr 4 ? 7 'Architecture is a misconception' Chris Poulissen has created a number of striking bridge designs. Yet he prefers not to call himself an architect. An interview with the keynote speaker at the fib Symposium 2017. 8 ? 13 Africa's largest suspension bridge To improve the transportation network between the capital city Maputo and the south of Mozambique, a suspension bridge with a total length of 1225 m is being constructed. 64 ? 67 World's largest sea lock The Noordersluis in IJmuiden (The Netherlands) is being replaced by a new gigantic concrete sea lock, made from 290 000 m 3 of concrete, that will provide defence against the rising sea levels. 1 Partners 144 Service / online 144 Colofon June 2017 / 69th Volume inhoud 3 2017 Inhoud 3 74 Foundation glass arch bridge Green Village, Delft University campus, The Netherlands Rob Nijsse, Ate Snijder 80 E-line station Den Haag, The Netherlands Jorrit Blom 86 Foundation Shanghai Tower, China Jian Gong, Weijiu Cui, Yong Yuan 90 Façade Infosys multi level car park, Pune, India Ajit Vasant Bhate 96 Elevation and refurbishment lock bridges Albert Canal, Belgium Robert Somers 102 Strengthening Kuhbrücke/ Hildesheim bridge, Germany Hermann Weiher, Katrin Runtemund, Andreas Praus 108 Bridge collision protection ramp, Kampen, The Netherlands Alex van Schie 113 Almonte River Viaduct, Spain Guillermo Capellán, Javier Martínez, Emilio Merino, Pascual García-Arias 118 European Central Bank (ECB), Frankfurt, Germany Alexander Berger, Manfred Grohmann, Klaus Bollinger 122 Campus Tower Hamburg, Germany Markus Krah 126 New grandstands KV Ostend, Belgium Johan Veys Pieter van der Zee 130 Hospital AZ Zeno Knokke, Belgium Axel Rémont, Vincent Servais, Stephanie Pareit 138 Train station Herstal, Belgium Jean-Philippe Jasienski, Abdelmajid Boulaioun, Nathalie Balfroid, Steve Conard Beste Cement-lezer, dear Cement-reader, For probably everybody this edition of Cement will be special and therefore some explanation seems to be appropriate. For the Dutch readers, besides content (more foreign projects) and the large number of pages (almost twice the usual size), the language (English) is also special. For foreign readers the journal on itself will already be special. For the foreign readers: Cement is the Dutch journal on concrete for structural engineers for already 69 years. The eight editions per year consist of papers on structural issues and challenging projects, in which the various aspects, like architecture, structural design, material technology and execution, are illustrated. For the Dutch readers: because of the international 2017 fib Symposium being hosted in the Netherlands (Maastricht, June 12-14, 2017), it was decided to combine special symposium sessions with this English edition of Cement and to also distribute it among the participants of the symposium. The theme of the 2017 fib Symposium is 'High Tech Concrete: Where technology and engineering meet'. In order to contribute to a fib symposium you are supposed to supply a scientific paper, that will be peer reviewed. Generally, this is a barrier for people from the engineering practice to participate. On the other hand, the largest projects worldwide are done by engineers that have very wide knowledge and broad experience worthwhile sharing with others. So, there was this idea to give them the opportunity to present projects by only supplying general information and interesting photos and figures. Since this is not acceptable for the proceedings of the symposium, and, in fact, is similar to the content of Cement, the idea for a special English edition of Cement, a meeting point for Dutch and worldwide engineering, was born. Reviewing, gathering the required information and bringing everything in the desired format, resulting in this special fib Cement issue, was thanks to the efforts of: Paul Lagendijk Delft University of Technology Mladena Lukovi? Delft University of TechnologyHanneke Schaap Aeneas Media We also want to thank the authors for their very valuable input and cooperation. Dick Hordijk Editor-in-chief Cement and Chair Organizing Committee 2017 fib Symposium Jacques Linssen Editor and publisher Cement Cover photo: Almonte River Viaduct, Spain credits: Rúbrica, Castellón (Spain) 3 2017 Inhoud 'Architecture is a misconception' 3 2017 4 thema Chris Poulissen, from the Flemish part of Belgium, has created a number of striking bridge designs together with his partner Laurent Ney, including in the Netherlands. Yet he prefers not to call himself an architect. "Forget that word. Architecture isn't important. There are so many more serious matters in the world, so many bigger challenges." 'Architecture is a misconception' 1 Cement's editorial staff talk to Chris Poulissen, keynote speaker at the fib Symposium 2017 thema 5 1 De Oversteek, Nijmegen, The Netherlands 2 Ghatkopar Koparkhairne Bridge, Mumbai credits: Ney & Partners Career Chris Poulissen began his career at AWG (Bob van Reeth's Architect Work Group). He soon met Laurent Ney (during the renovation of the Koning Boudewijnstadium, for example), who was working as an engineer at engineering firm Bureau Greisch. In 1995 Poulissen launched his own firm: Architectenbureau C. Poulissen, which later became Poulissen & Partners. Poulissen and Ney have always cooperated closely. Increasingly, they have been focusing on designing bridges. When they received the assignment to design the Oosterweel Link in Antwerp, they founded the firm Ney-Poulissen Architects & Engineers, which was renamed NP-Bridging in 2011. They now work all over the world, including in the Netherlands, India and Japan. Well-known Dutch projects include De Oversteek and De Lentloper, both recently built in the city of Nijmegen. "I can't stand misery in the world" Ask Poulissen where he gets his ideas for his designs and he will tell you he doesn't know. "The best designs evolve gradually, in a process with multiple people. You have to consider all of the interests at play. Things like ecology, flora, fauna, noise pollution, contamination. It's barely about the form. For example, when Laurent and I were working on the bridge project 'De Oversteek' in Nijmegen (photo 1), we didn't anticipate before- hand that those arches would be there. That idea materialised during the project, in part because of the limited budget. That forced us to find clever solutions. And the solution with the arches turned out to cost a lot less, and it doesn't require much maintenance. There are no joints, no bearings. The design for the bridge 'De Lentloper' (photos 3 and 6) didn't fall out of the sky either. We turned the reference design, which was based on prefab girders, completely inside out. In the end it resulted in a design that cost 30% less than the budget and also generated 25% more surface area (fig. 4)." Design competitions The most important challenge in a design process is not what something will eventually look like, but what the real needs are. That's why architecture is a misconception according to Poulis- sen. "It's not about architecture, it's about the bigger picture, where you stand in life." Poulissen and Ney had to fight for two to three years to get a footpath onto their design for two mega- bridges in Mumbai (fig. 2). The overwhelming majority of the city's 20 million inhabitants doesn't have a car. "In my view they also had a right to move from one side of the river to the other. For me, that's the essence of bridges. De Oversteek was about a footpath too. It was supposed to be 1.5 km long, but according to the municipality that's why it would never be used. But as it turns out, it's a huge success, almost too huge if you look at how busy it is there sometimes." That explains why Poulissen is not a fan of the design competi- tion phenomenon. During a contest for Groenplaats, the historic square in Antwerp, Poulissen went so far that he barely even showed his design. "I did have a design on me, but I said beforehand that I didn't know if that would be it and that I didn't know what would be it either. I also said that if you want to get yourself into a huge mess, you should make a design and say 'this is it'. I advised them to talk to the people who live and work near the square to find out what their interests are. We had no choice in my opinion. We had to ask these people before putting even a single line onto paper." Another major disadvantage of design competitions is the waste according to Poulissen. "We have to stop making each other miserable. Take De Oversteek. 2 ?Architecture is a misconception? 3 2017 6 the raw materials, the nature of the needs. You should be guided by the materials. That's what will tell you what form it should have, so to speak." Indeed, cooperation is important to Poulissen. It's taken for granted in the Netherlands. "It's really part of your DNA. It's for good reason that you're pioneers in public-private partnerships. But in Belgium people don't trust you if you suggest working together. It makes them wonder, 'what does he want from me?'" In practice, not much always comes out of an integrated approach. Architects design something that they think will please the client. "It makes it easy to determine what kind of a risk someone should take. That idea is out of date. Why not have a designer bear part of the financial risk of a project for once? I guarantee you that the world would look much differ- ent. Undoubtedly more exciting, interesting, intense, serious and responsible." "So it's much more about what's important to people than it is about the form. We always try to discover what the individual interests are. In everything, in every project, in every conversa- tion. For an investor, that means a return on your investment. The bridge or the building is not the point at all. He couldn't care less about that. Me either, for that matter. What I want is to make the world better. I can't stand all this misery. I really can't stand it. My body reacts to it. That's why I wanted to make a small contribution in India to reducing the enormous gap Do you really think that if one of the other seven candidates had won it would be a much worse bridge? Our competitors put a lot of time and energy into a design that didn't win and therefor wasted valuable money. And money is probably not even the most important problem. What do you think happens to young people who miss out on a project, and miss out again, and again? That's how you destroy ambitions and dreams. Of course, I understand why these competitions are held. Clients have to be able to justify their decisions. But I think we can do better. And why shouldn't a losing team put their ideas at the disposal of the winner, so he can make his design even better? Now that knowledge is completely lost." Cooperation The process is still too scattered according to Poulissen. In practice, it often comes down to an architect conceiving of something based on form, and so he is creating a mechanical problem that an engineer will have to solve. The engineer will use all kinds of complex sums and complicated programs to show that the construction meets a standard. And once he has calculated everything, the contractor has to find a way to build it. But the contractor isn't always aware of where the design came from. Because we are not allowed to provide him with information during the tendering stage. Sure, sometimes there's this competitive dialogue, but that's in writing. That's not a dialogue! His lack of information will cause the contrac- tor to do everything he can to reduce risk. So he will think of yet more ways to adapt the construction. That's not how it should be done. You have to develop things together. Deter - mine together how a project should take shape, when and how. It's about the nature of the construction, the nature of "It's not about architecture but about the bigger picture, where you stand in life" 3 thema 'Architecture is a misconception' 3 2017 7 3 De Lentloper, Nijmegen, The Netherlands credits: Ney & Partners / Thea van den Heuvel 4 The design of De Oversteek originated from a reference design based on prefab girders and the idea of making the best possible use of the pedes- trian surface of the cross section 5 Making the pie bigger gives the players more space 6 De Lentloper credits: Ney & Partners / Thea van den Heuvel themselves and therefore function better (fig. 5). That makes people happy. In the end, I make sure that it's a coherent entity again, that the pieces of pie come together again. You need good people for that. I once heard that you can tell if someone's intelligent because they will surround themselves with more intelligent people. I firmly believe that. The people working in my office are all smarter than me. Otherwise they wouldn't be here, because we could do what they do ourselves. And luckily there's Laurent. He's seven times wiser as me." ? Jacques Linssen and Dick Hordijk between the poor and the rich. The footpath that I mentioned earlier is an example of that. Believe me, what the bridge looks like doesn't interest me much." Developer "People sometimes say that I have a lot of luck. That's true. But I did create situations that make it possible to have good luck. I bought that ticket to India. I took the risk 18 years ago of devel- oping that old warehouse on the 'Eilandje' Island in Antwerp. I once said that I am a developer. Not in the conventional sense of the word. But I do feel like a developer. I have brought people together and instilled enthusiasm in them. I try to set processes into motion. My role in doing so is to let people put their heads together and come up with a design. I try to ask the right questions. For as long as it takes until I understand what people are saying. And then I grab a marker and draw it on a flip-over. By talking and drawing you're using two channels simultaneously. That's a great help in understanding what's meant. But take a look at a large engineering firm. There won't be a flip-over anywhere in sight! Just a TV screen hanging somewhere for presentations. But only one person out of ten probably dares to go near the screen. People don't participate nearly enough." Intelligent "I try to be the oil in the machine. It's what gets everything running smoothly and effectively. I sometimes explain my role using a pie as an analogy, in which everyone involved in a project is a piece of that pie. What I do is try to make the pie bigger so that everyone has more space, more chance to be "Why not have a designer bear part of the financial risk of a project? The world would look much different" 4 5 6 ?Architecture is a misconception? 3 2017 8 thema Africa's largest supension bridge Mozambique, located on the east coast of southern Africa with a coastline of 2800 km (fig. 2), is rich in natural resources and is rated as the 4th fastest growing economy in Africa. Part of the Mozambique's National Development Master Plan is to improve the transportation network between the capital city Maputo and the south of the country. To achieve this aim, a bridge is being constructed across the Maputo Bay as a connection to South Africa. After its completion in 2018, it will be the longest suspension bridge in Africa with a main span of 680 m and a total length of 1225 m. Construction of the Maputo-Katembe Bridge (photo 1 and fig. 3) started late 2014 with a total project value, including the southern link roads, of approx. US$ 700 million. Design and execution is being carried out by China Road & Bridge Corporation (CRBC) and is based on FIDIC's Silver book EPC contract. German consultant GAUFF Engineering is responsible for quality supervi- sion as well as design verification according to the Eurocode. Concept of the bridges The bridge consists of reinforced concrete approach viaducts on the North and South banks of the crossing, which connect to the main span, a suspension bridge constructed of steel box girder sections, with two large subsoil gravity anchor blocks that are filled with sand and concrete. The bridge will carry four traffic lanes, two in each direction, with a design speed of 80 km/h. 1 Africa?s largest supension bridge 3 2017 thema 9 The North and South Approach bridges are being constructed using two different design and construction methods influ- enced by the local urban development. In the north, located in the middle of a very congested central business district and harbour, the approach bridge will be a balanced cantilever 853 m long construction rising up towards the main pylon. The main distances between the piers are 119 m. The Southern Approach Bridge, situated in a totally rural area without any obstructions, will be built using prefabricated post-tensioned T-beams to form its total length of 1234 m (photo 4 and 5). The approach bridges connect on either side to a single-span double-hinged suspension bridge with a centre span of 680 m, supported by hangers attached to two cables, which are draped over the main cable saddles of the towers and connected to the anchor blocks on each side of the river. Side spans are 260 m and 285 m long. The bridge concept was designed according to Chinese stand- ards with the overall design verified against Eurocode specifi- cations and specifications according to the South Africa Trans- port and Communications Commission (SATCC). Especially for the pile foundation changes in the amount of reinforcement were required considering considering the requirements by the different codes. Each gravity anchorage is made up of the foundation, splay-saddle buttress, and anchorage chambers. Some of these chambers are empty, and some are filled with concrete and sand requiring a specific density, all adding to the total weight of the structure. Each shaft has an external diameter of approx-imately 50 m, a wall thickness of 1.20 m and a wall panel depth of up to 56 m. The deepest anchorage structure was the one on the south side of the crossing; with 37 m it is believed to be one of the world deepest constructed during the last years. Figure 6 gives the structural detail of the shaft and photo 7 shows the final construction stage for the completion of the anchorage block inside of the shaft. Photo 8 illustrates the completion of Africa's largest supension bridge Jörn Seitz GAUFF GmbH & Co. Engineering KG, Nuremberg (Germany) Dean Gary Swanepoel GAUFF GmbH & Co. Engineering KG, Maputo (Mozambique) B. Pengyu China Road and Bridge Corporation (CRBC), Bejing (China) 1 Maputo construction site: North Approach Bridge with two of the eight piers for the free cantilever bridge that will lead over the anchor block credits photos: GAUFF Engineering2 Map of Mozambique 3 Visualisation of the finished Maputo Katembe Bridge 3 2 Africa?s largest supension bridge 3 2017 10 thema llerller ller bottom plat e0.49 (g roudwater level) medium sand sludge ne sandston e muddy siltston e clay medium sand clay ground line concr ete cushio ntop plat e ground line theoretical IP point S7 pier K4 + 787 S6 pier K4 + 742 (1:800) planting soil sludge th eor etical centerline of splay cabl e IP + 25.900 QZK17 5000 4760 3600 120 250 200 150 150 200 250 120 h600 800 600 -33.600 773.9 2.400 -0.86 -12.86 -21.75 -30.56 -47.46 2350 43° 38 0 20. 5° using the Crosshole Sonic Logging (CSL) testing method by an independent third party after 28 days. Concrete cubes were manufactured even for 365-day compressive strength tests. Pylon, cables and steel box girders The main structure of the tower is formed of rectangular hollow box sections, with a length of 7.00 m and a width of 5.00 m. The wall thickness of the upper tower is 1.00 m, and this increases to 1.20 m towards the bottom, resulting in a total thickness of 1.80 m at the base. The final height of the tower on the north, Maputo side, will be 135 m and on the south, Katembe side, just one meter higher (fig. 10 and photo 11). Prefabricated parallel wire strands will be used for the main cables, which are made up of 91 galvanised high-strength steel wires, 5 mm in diameter with a nominal tensile strength of the massive concrete construction built on the shaft to hold the main cables. Piling and diaphragm walls for the anchorage shafts As there was no comparable project in Mozambique for the design of the bridge foundation piles, the design was based on the findings of a geotechnical investigation, which started two years ahead of the actual construction work. Pile construction for the towers and foreshore bridge piers began in tandem with the anchorage excavation. Before pile production could begin, their bearing capacity was verified using static test loads. Based on this all 331 piles were optimised in diameter and length. A total of 283 piles were constructed for the approach bridges, each with a diameter of 1.50 m and an average depth of 50 m, and 48 piles were installed for the towers, 24 at each tower, and each with a diameter of 2.20 m and length of 110 m at the south tower and 95 m at the north. The excavation for the piling followed the international reverse-circulation-drilling method. The quality and integrity of the concrete in all piles was verified over their total length 6 5 4 Africa?s largest supension bridge 3 2017 4 Pylon M2 (south) and piers of the approach bridge 5 Second of 34 piers of the Southern Approach Bridge (December 2016) 6 Cross section of southern shaft with charateristic soil layers 7 Construction stage of the southern anchor block 8 Massive concrete construction of the northern anchor block 1670 MPa, resulting in an outside diameter of 509 mm and a total strand length of 1317 m. The main cables are connected on each side of the bay into the gravity anchorage blocks (photo 9 and 12). The cables are specially protected against corrosion in a permanent airtight system. For the hangers, galvanised high strength steel wires will be used. The transverse distance between the main cables hangers is 21.90 m and the standard distance between the hangers along the bridges main span orientation is 12 m, with the length of hangers ranging from 73 m at the towers to 3 m at midspan. The steel box girders are being manufactured in Nantong near Shanghai in China and will be delivered to Maputo by ship by manufacturer ZPMC. Special concrete One of the unusual aspects of the concrete on this project was the addition of up to 40% fly ash. This not only offers immediate cost savings but also long term benefits. The fly ash is produced in and delivered from South Africa and gives the concrete an extremely high durability, a fact which was confirmed by the University of Cape Town's Concrete Materials & Structural Integrity Unit which performed Durability Indexes testing on the samples cored from the bottom slab of the anchorage. The tests performed were the OPI- oxygen permeability, WSI-Water sorptivity Index and the CCI-chloride conductivity index. The results obtained were confirmed as the best test results ever obtained from a site concrete. High workability was of vital 7 8 12 thema 4.200 pylon prole 12 m A-A 5 m 7 m 0.000 B-B 8 m 133.0 m 8 m 5 m 133 m 7 m 47.0 m 70.1 m5 m3.5 m pylon elevation 5 m 17.4 m 5 m 136.376 2 m 6 m 2 m 6 m 9 Installation of the steel construc- tions for the anchorage of the main cables (north side) 10 Details of the pylon 11 Construction of southern Pylon M2 (January 2017) 12 Construction of the southern anchor block 9 10 Africa?s largest supension bridge 3 2017 13 importance to the project during the casting of the anchorage base slabs and pumping the concrete up to heights of 140 m. Laboratory testing confirmed that the concrete was still workable up to 16 hours after the initial mixing. This is directly related to the high quantity of fly ash and a retarder from China specifically formulated for this project. Concrete cube crushing strengths at 28 and 90 days have confirmed a remarkable strength gain. C40 concrete had results of 51.9 MPa and 69.5 MPa at 28 and 90 days respectively. Producing sustainable concrete and most importantly a sustainable project is particularly important to CRBC and the client. Achieving a balance of social, environmental and economical factors is part of the contractor's quality manage- ment system which was developed by GAUFF Engineering following the 'Triple Bottom Line' concept from the United Nations' Bruntland Report. Through this CRBC aspires to produce a sustainable structure as a whole and to promote sustainability across the board. Reduction of its carbon foot- print by reducing CO 2 emissions is part of the company's mix-design philosophy and is achieved through the use of fly ash as an extender; it has resulted in dramatically lowering the cementitious CO 2 emissions of the concrete from an estimated 352.5 kg CO 2/t to 229.5 kg CO 2/t, a reduction of 35%. Summary For this project, CRBC and GAUFF together with the client have developed a comprehensive quality management monitor - ing system, which covers all aspects of construction in Maputo and also the extensive production of the complex steel compo- nents being manufactured in China. The calculations using Chinese standards and their verification against Eurocodes were completed in June 2016, alongside the production of piles and diaphragm walls. In the coming 18 months the construction work will focus on steel fabrication for the suspension bridge, erection of the main cables, lifting of the 57 steel box girder segments, and the respective quality monitoring of the production in China. At the same time the construction of the highly demanding balanced cantilever post tensioned North Approach Bridge will commence (photo 1) as well the installation of the T-beams for the Southern Approach Bridge. Handover of the new bridge to the Mozambique Nation is scheduled to take place early 2018. ? 12 11 Africa?s largest supension bridge 3 2017 14 thema Queen Máxima bridge A sleek and open bridge design three separate decks. This resulted in a more open construction and, very importantly, in the opportunity to build tail bridges. If the deck had been about 30 metres in width it would have been impossible to build tail bridges. Instead, it would have been a bascule bridge. The difference between a tail bridge and a bascule bridge is, that the counterweights of a tail bridge are moving in the open air, besides the foreland bridges and, in closed position, they are visible above the deck (photo 2), while a bascule bridge has its counterweight under the bridge, mostly in a large cellar. As a result, a bascule bridge has higher lifting capacity than a tail bridge but due to the large cellar is less aesthetically appealing. Another wish of the architect was to make a slender deck construction with no visible cross beams. So the concrete decks of the land span bridges have a continuous height of about 1.2 m in combination with spans of 27.5 m. On the locations of the intermediate supports, the bridges for the road traffic are supported by two conical columns. The bridge for cycling/ pedestrians is supported there by one column. All columns have a circular cross section, with a diameter varying from 1.5 m at the base to 1.2 m at the top. The column under the bridge for bicycles and pedestrians is placed eccentrically in the transversal direction. To make the construction stable this bridge is connected to the adjacent bridge for road traffic, using concrete beams with a circular cross section (photo 3 and fig. 6). The design of the steel bridges was given a lot of attention. The steel river spans have the same deck height as the land span bridges and the tails are beautifully shaped. The use of tail bridges resulted in open structures for the concrete piers adja- cent to the river. Details also had the attention of the architect. This resulted in a The Queen Máxima bridge (photo 1) has three adjacent bridge decks, in which two parallel tail bridges are situated. The tail bridge at the east side is connected to one of the decks for the road traffic and to the deck for the cycling/pedestrian lane. The tail bridge at the west side is only connected to a deck for road traffic (fig. 4). The concrete land span bridges are 140 and 50 m long and the steel tail bridge decks are approximately 19 m. The tails contain the counterweights that ensure the smooth opening and closing of the bridge with a minimum of energy consumption. The project is characterized by its unique design, which tended to be as sleek and as open as possible. Architectural design The architectural design was very important to the client. Therefore, Mobilis TBI closely collaborated with the architect, Syb van Breda & Co Architects and designed a bridge that fully exploited the structural possibilities of the applied materials and met the wishes of the client to be elegant. At first a single deck bridge was specified, so traffic lanes could be assigned freely. This would have resulted in a width of the deck of about 30 metres and a very dark area under the bridge. In the last stage of the tender the architect proposed creating In 2016 Mobilis TBI completed the Queen Máxima bridge, an energy- neutral tail bridge named after the Dutch queen. It was commissioned by the city of Alphen aan den Rijn and crosses the river Oude Rijn. The implementation of energy-neutral requirements was a unique selling point in the offer of Mobilis TBI. It is achieved by the installation of a field of solar panels that can generate the energy for the moving of the steel bridge parts, lighting and all other equipment. thema Queen M?xima bridge 3 2017 15 beautiful shape of the handrail, the lighting masts and the signs for the road traffic and the shipping traffic. Also the lighting on the bridge and under the bridge was designed by the architect. The space under the bridge at the south side will be turned into an area with foot paths and a water garden, with stairs as a connection for pedestrians to reach the bridge deck (photo 3). Structural design As can be seen in figures 4, 5 en 6, each of the three decks of the land span bridge in longitudinal direction is a continuous beam without visible joints at the locations of the intermediate supports. On both sides of the river the adjacent deck spans form rigid portals, together with the underlying columns. In this way, the movable bridge has rigid bearings in the horizon- tal direction and there is also a rigid support to withstand the load of a ship colliding with the river piers. At the locations of the other piers, including the abutments, the bridge is supported by rubber bearings. Queen Máxima bridge 1 1 Queen Máxima bridge, Alphen aan den Rijncredits photo 1 and 2: Syb van Breda & Co Architects2 Tails with counterweights, visible above the deck 3 The stairs for pedestrians to reach the deck and the circular beam to connect the decks 4 Top view on the bridge André Bouman, Nick Nass Mobilis TBI The five columns for each intermediate pier and the columns for the river piers are placed on a continuous foundation beam. At the intermediate supports, the foundation beams are supported by prefab concrete piles 450 mm square. At the river piers, steel tubes with a diameter of 610 mm are used for the foundation, in order to have enough strength to withstand a ship collision. Both prefab and steel piles are raking at 1:10. The abutments are grounded on reinforced soil constructions. RRRRRR eastern bridge for road traffic western bridge for road traffic bridge for bicycles and pedestrians 2 3 4 RRRRRR Queen Máxima bridge 3 2017 16 33001800 750 750 G F +11.931 +6.700 +6.700 +8.293 +5.240 6200 750 4700 750 14000 250 2050 2150 100 150 (PVR tot voorzijde beton) 1275 17975 1800 5500 250 14500 1425 1525 14300 100 7000 7000 150 (PVR tot voorzijde beton) 260 18500 3800 16700 625 750 15104 1970 901 80 5 (a) Longitudinal cross section; (b) river crossing with tail bridges 6 Cross section of the deck 7 The three dimensional finite element model designed with Scia Engineer 8 A view of the placing of the second movable deck credits: Hollandia Infra and Sarens NL Special load case Additional to the traffic loads as listed in the Eurocode, the contract prescribed a special load, namely the transport of heavy concrete beams made by Consolis Spanbeton in Koude- kerk aan den Rijn. Spanbeton, who also made the prefab concrete beams for the Queen Máxima bridge, is very happy with the realisation of the bridge, because now they can trans- The whole structure with all the loads was modelled in a three- dimensional finite element model with the Scia Engineer soft- ware (fig. 7). Deck construction The deck spans are made of prefab, pre-stressed beams with a cast in-situ concrete layer on top to form the traffic deck. At the location of the supports, prefabricated beams are connec- ted by wet joints. In this way the prefab beams form a continuous girder and no cross beams are visible (photos 3 and 9). 8 5a lichtmast B B C C D D E E F F G G H H II AANZICHT A-A200 A A lichtmast lichtmast lichtmast lichtmast lichtmast leuning beeindiging ntb in UO-fase leuning beeindiging ntb in UO-fase 27900 27125 17975 27460 27460 27460 27460 27900 210740 (ontwikkelde lengte over as) maatv. in As MWA1 continuous beam continuous beam rigid portals 5b beam, to compensate for the eccentric placing of the column under the bridge for bicycles and pedestrians 6 7 thema 3 2017 17 port without restrictions, beams with a length of about 100 m. The impact of this additional requirement on the structural design was minimal. Execution Because of the slender design, in a lot of places it was difficult to apply all the reinforcement that was needed. Especially at the locations of the wet joints (photo 10) a large amount of reinforce- ment was required. As can be seen on photo 11, the circular coupling beam between the road deck and the pedestrian deck also needed much rein- forcement. This beam has to compensate the eccentric placing of the deck for cyclists and pedestrians which results in bending moments and shear forces. Extra care was taken when the steel movable decks (weighing 220 and 270 ton) were placed. The decks were placed using a crane with a fixed position on a pontoon. This combination as a whole was moved in the right position to situate the decks (photo 8). Movement of the tail bridge Each of the two separate movable decks of the river span has two tails supported by a column of the river pillar. The tails are filled with ballast, used as the counterweight. The movement of each bridge is enabled by two hydraulic cylinders, which are located in a recess in the columns of the bridge pillars. Accor - ding to the contract the bridge is engineered to allow a non- availability for shipping of 3 days a year. To withstand a collision between the bridge deck and a ship, the front of the deck is supported in the horizontal direction perpendicular to the bridge axis. Environment The Queen Máxima bridge is energy neutral and a sustainable structure; the slender design of the bridge required considerably less material than other types of bridges would have. The impact on the environment is therefore low. The bridge was opened for traffic on December 21, 2016. ? ? PROJECT DETAILS client Alphen aan de Rijn contractor Mobilis TBI parallel contractors Hollandia Infra (steel bridges) Aannemingsmaatschappij Van Gelder (roads and earth works) prefab concrete beams Consolis Spanbeton architect Syb van Breda & Co Architects 9 10 11 9 A view under the fore - land bridges credtis: Syb van Breda & Co Architects 10 A wet cast in situ con- nection combines prefa- bricated beams to a con- tinuous deck construction above the piers credits: Mobilis TBI 11 The reinforcement of the concrete coupling beams between the road deck and the pedestrian deck Queen Máxima bridge 3 2017 18 thema -0 .6 00 m - 4 .6 00 N.A .P . mi n.7 00 0 2 5 00 0 15 N20 7 3 600 14 13 12 11 10 9 1 2 3 4 5 6 7 8 3 3 660 3 3 985 3 3 985 3 3 985 3 3 994 3 3 255 3 8 642 3 8 29 0 14 362 31 143 30 65 0 30 99 5 30 986 30 622 2 2 50 0 joint joint joint joint joint joint joint joint joint joint joint joint joint joint CVR building Amalia Bridge Waddinxveen 1 New Gouwe bridge beside aqueduct will ease traffic on A12 Where the A12 and A20 motorways merge, before passing under the Gouwe aqueduct, both the flow and safety of road traffic become critical. In order to expand the road network around Gouda, under the name 'A12 Parallel Structure', the province has constructed two new roads: the Extra Gouwe Crossing and the Moordrecht Bow. Within the Extra Gouwe Crossing, the 'Amalia Bridge', designated also as 'ancillary structure KG', showed to be highly challenging; both structurally and in terms of fitting into the existing situation. thema Amalia Bridge Waddinxveen 3 2017 19 1 2 3 4 5 6 7 8 910 11 12 13 14 15 Kanaaldijk Gouwe Wilhelminakade Highway A12 Highway A12 Concorp Gouwe N207 - 0 .6 00 m - 4 .6 00 N.A .P . mi n.7 00 0 2 5 00 0 15 N207 3600 14 13 12 11 10 9 1 2 34 567 8 33 660 33 985 33 985 33 985 33 994 33 255 3 8 642 3 8 29 0 14 362 3 1 143 3 0 65 0 30 99 5 30 986 3 0 622 2 2 50 0 joint joint joint joint joint joint joint joint joint joint joint joint joint joint CVR building The road crosses the river Gouwe just north of the Gouwe aqueduct by means of a new drawbridge (photo 1). Apart from the Gouwe, this structure also crosses local roads (from west to east): Kanaaldijk (N484), Wilhelminakade and N207. The bridge consists of a movable section (the leaf, a steel structure), and concrete approach ramps to the east and west of the bridge (fig. 2 and 3). Situation Because structure KG lies immediately beside the existing Gouwe aqueduct, this object formed the de facto working boundary on the south side. With this in mind, and in order to minimize the impact of construction activity on the existing aqueduct, it was preferable to place the bridge as far as possible from the A12 (to the north). It was essential to take into account not only the visible parts of the Gouwe aqueduct, but also the subsurface grouted anchors. However, another barrier was formed by several commercial properties on the northern side. One of these properties is a confectionery manufacturer (Concorp), whose production depends on sensitive weighing equipment. Together with the aqueduct, these factors constrained the position of the bridge in the north-south direc- tion. Likewise, the position of the western abutment was restricted by the presence of another existing object: a road- traffic control centre. This building is equipped with ICT equipment for control of traffic systems, and therefore has a critical function in traffic management. To avoid jeopardizing this building and its function, the western bridge abutment has been positioned at a sufficient distance. Fortunately, the location of the eastern abutment was not subjected to any positional constraints. What did determine the position was the maximum extent for the approach embankment in order to maintain the necessary landscape quality in the vicinity of the structure. Design of deck structure The total length of structure KG from eastern to western abutment is approximately 450 m. The bridge is divided into an eastern approach ramp (124 m), the bascule pit and steel leaf (together 45.5 m) and the western approach ramp (280 m, all lengths approximate). The required 2 × 2 lanes, in combination with a median of about 3 m width (ensuing from the landscape plan), and bevelled fibre reinforced plastic edge elements (ensuing from the visual quality plan) result in a total deck structure width of approximately 21.6 m (fig. 4). Construction method To construct the approach ramps quickly and with minimal disruption to the surroundings, the deck structure was built using precast concrete beams. The first beams were placed in position from the side of the abutments, while the remaining sections were hoisted into position by cranes from each finished section of the deck. This working method meant that there were almost no interruptions to traffic on the underlying road network. Moreover, this also avoided the need for temporary structures to create a stable foundation for the cranes on the soft Gouda ground. Nevertheless, this did make it necessary to dimension both the deck and its substructure for the crane load. ir. Bas van den Berk Heijmans Infra 1 Amalia Bridge over the Gouwe, Waddinxveen 2 Top view on the Amalia Bridge 3 Longitudinal cross-section 2 3 Amalia Bridge Waddinxveen 3 2017 20 20 980 40002660 6599 19 920 14 500 2660 4000 2000 81.160° 93.550° N.A.P. 4 Cross section 5 The land piers are designed as double T-pillars on a footing which is founded on precast concrete piles 6 T-heads that hold the rods to the ends of the deck supporting beams This enabled the construction of a foundation structure that fits into the existing situation (grouted anchors of the Gouwe aque- duct) but is still wide enough to support the deck structure. The land piers are made of concrete with strength class C55/67. To achieve sufficient load-bearing capacity in the soft Gouda subsoils, it was necessary to drive the precast concrete piles approximately 10 m into the firm sand layer. This resulted in a pile toe depth of 20 to 25 m below sea level. Piling and vibration analyses carried out beforehand indicated that pile-driving was feasible, and would not lead to unacceptable risks for existing objects, particularly the traffic control building and Concorp. The subsequent pile-driving work proceeded smoothly, and all piles were placed at the correct depth in the correct manner. A challenge for the pier design was the fact that the outer box girders, each up to 38 m in length, had to be placed on a 4 m long cantilever on top of the pillars. As described earlier, it was also necessary to consider crane loads together with the hoist- ing weight of the precast beams. As a consequence, the upper reinforcement in the deck support beams incorporates several layers of Ø40 mm rods. These rods are mechanically anchored to the ends of the deck supporting beams by means of 'T-heads' (photo 6) in order to avoid complicated reinforcement detailing in that small space at the end of the construction. River pier Row 11 is the position of the support pier for the moving leaf of the drawbridge. This pier stands in the river Gouwe. The geometric and structural design of this pier is similar to that of the land piers. There is one major difference: this river pier has to be able to withstand a collision from water-borne traffic. As a result of the magnitude of this load, prefab concrete piles could not be used, so steel tubular piles were used for this foundation. To optimize the tubular pile dimensions, a more detailed analysis of the navigation channel and nautical traffic was carried out resulting in a reduction of the collision loads, which meant that Structure The span dimensions are based on several preconditions. First of all, the beams could not be too heavy, due to the chosen construction method. Furthermore, the positional constraints arising from the current situation (i.e. traffic control building, Kanaaldijk, the necessary distance from the Concorp site, Wilhelminakade, intersection with the Gouwe and the N207) also played a significant role. Finally, it was desirable to choose a beam length that could be repeated as often as possible. For the eastern approach ramp this resulted in four spans of 31 m, and for the western approach ramp, six spans of 34 m and two spans of 38 m (approximate lengths). The transition from span to span is formed by non-rigid expansion joints and rubber expansion joints in a steel claw. The spans are constructed from precast concrete I-beams with tapered box girders at the sides. Land piers At rows 2 to 8 and 12 to 14 (fig. 2 and 3), the deck structure rests on land piers. These piers are designed as double T-pillars on a footing which is founded on precast concrete piles (photo 5). 4 5 6 thema Amalia Bridge Waddinxveen 3 2017 21 7 An analysis of the navigation channel and nautical traffic led to a reduction of the collision loads and smaller tubular pile dimensions 8 Bascule pit: the beam at row 9 is modelled schema- tically as a rib that is part of the 2D element, which itself is the roof of the bascule pit Obviously this had to wait until the steel leaf and ballast box were in place. Because the beam was still not finished at that point in time, and, therefore it lacked sufficient strength to support the prefabricated deck beams, a temporary support structure was built below the beam, which was later removed once the roof was ready. The same SCIA Engineer model was used for this phase as for the final phase, except without the roof. In addition to the models for the purpose of the overall structural analysis, a separate model was also made to determine the forces in the consoles. These consoles are cantilevered from the concrete wall, and are subject to dynamic forces from the moving parts. A push-pull rod transfers forces from the leaf to these consoles via the panama wheels: large pinion-driven gears that open and close the steel leaf of the drawbridge. A complicating factor in the structural analysis is the varying angles at which the forces act on the concrete consoles, depending on the position of the steel leaf. Another is the fact that the forces also switch from tensile (when the bridge is raised) to compressive (when the bridge is lowered). On December 23 2016, the bridge was opened , providing the alternative route for traffic. As a result, one can choose such a route so that the traffic jam is avoided and with this, the problem of major bottleneck is solved. Although it was a challenge to fit the Amalia Bridge in the existing situation, Heijmans has managed to engineer and successfully build the bridge on time. ? ? PROJECT DETAILS project Bridge over the Gouwe river (part of A12 Parallel Structure) client Province of South-Holland contractor Heijmans Infra architect Zwarts and Jansma structural design Heijmans Infra first pile bridge KG 12 June 2015 bridge KG opening end of 2016 smaller tubular pile dimensions would be sufficiently robust (photo 7). Final phase of bascule pit modelling The bascule pit (photo 8) was structurally analysed using a 3D schematic model in SCIA Engineer. In this model, the beam at row 9 is modelled schematically as a rib that is part of the 2D element, which itself is the roof of the bascule pit. This beam spans approximately 15 m, and bears the weight of the precast deck above. Because the forces acting in this beam are dependent on the stiffness of the corner columns that support it, the analysis was performed both with the cracked and uncracked columns. Construction phase The preceding paragraph concerns the final phase. However, the roof was not yet in position during the construction phase. 7 8 Amalia Bridge Waddinxveen 3 2017 22 thema Approach bridge of Second Wuhu Bridge 1 Design Overall The approach bridges (from movement joint to movement joint) are designed to have three kinds of span arrangement. The basic one, consisting of six spans each 30 m long (6 × 30 m), is applied for bridges relatively close to the ground. The other two span arrangements are 5 × 40 m and 5 × 55 m. They are applied for approaches near the main bridge in consideration of budget balance between superstructure and substructure. There is a 200 mm wide movement joint between each span arrangement. Based on the road plan, the majority of bridges serve for six traffic lanes while a small part after a ramp serves four traffic lanes. So all the approach bridges can be distinguished as: - 5 × 55 m with 6 lanes; - 5 × 40 m with 6 lanes; - 6 × 30 m with 6 lanes; - 6 × 30 m with 4 lanes; Span arrangements and representative ending spans of approach bridges are given in figure 2. The Second Wuhu Bridge connects the highways south and north of the Yangtze River in Anhui Province in China. The total length of bridge is about 50 km and is composed by two main parts: the main bridge over the Yangtze River, a cabled stayed bridge with a total length of 1622 m and a main span of 806 m, and approach parts connecting the main bridge with the highway from the both sides. The approach bridges, which are about 26 km in total length, are designed to be fully externally pre-stressed continuous segmental box girder bridges. It is the first application of this type of bridge in China, and maybe also one of the first in the world with such large amount of segments cast in the same project. The project is scheduled to be built in four years and should be finished by the end of 2017. thema Approach Bridge of Second Wuhu Bridge 3 2017 23 1 The approach bridges of the Second Wuhu Bridge under construction 2 Deviator and diaphragm section details [m] Cross section The cross section is designed to be a single-cell arrangement with side wings (fig. 3). The elements are made with C50 concrete. Constant depth is designed for each kind of bridge. The height for 55 m span is 3.25 m and 2.50 m for 40 m span. The height for 30 m span of both six lanes and four lanes are 2.00 m. The deck width of box girders of six lanes bridge is 16.25 m and 12.50 m for the four lanes bridge. Due to the application of fully externally pre-stressed tendons, no pre-stressed tendons are arranged in the web and flanges. The dimensions are optimized to reduce the segment weight. The minimum thickness of top slab and bottom slab is 220 mm and 200 mm respectively. The web is design to have various thick- ness and the thinnest part is 330 mm. Optimizations of the section dimensions helps reducing necessary lifting equipment capacity. The same parts of sections for four kinds of bridges are designed to be as much as possible similar to reduce the complexity of precast forms. For four lanes bridge section, there are no transverse rib both inside and outside the box girder. For six lanes bridges, there are no transverse ribs inside the box due to its complex inner form, while transverse ribs are designed under both sides of the cantilevering deck to achieve the very long side wings. The rib section is inverted trapezoid for mold releasing. Segment Division All approach bridges are designed to have only four types of box segment: standard segment (A), deviator segment (B), strengthening segment (C) and diaphragm segment (D) (fig. 2 and fig. 4). The length for the first three types of segments is 3.00 m. Considering the lifting capacity, the length of diaphragm segment is set to be 1.40 m. In this way, the heaviest weight of diaphragm segment is controlled to be within 100 t, due to the consideration of both lifting and transport machines' capacity, as well as the cost of enhancing the temporary erection road. Deviator segment is the place where tendons steer. The only difference for deviator segment from standard one is two more deviator blocks at inner box. Strengthening segment and diaphragm segment are designed for the anchorage of tendons. The huge and concentrated force is a big challenge for structural safety at these two types segments. Both theoretical calculation and FEM simulation have been applied to optimize the shape and ensure safety and durability. For all approach bridges, the span at the end contains several standard segments, two deviator segments, two diaphragm segment and one strengthening segment (fig. 2). The span in the middle contains several standard segments, two deviator segments and two diaphragm segment. In total, there are 20032 segments for the whole approach bridge project. Ke HU, Zuqiao MA Anhui Transportation Holding Group Co. Xuefei SHI, Xin RUAN Tongji University 2 Approach Bridge of Second Wuhu Bridge 3 2017 24 3 Ending spans of approach bridges with their segment division 4 Standard section details [m] 5 External tendon profile 6 Storage of the segments 7 Construction site at the shore of the Yangtze River tendons to provide no more than 10 MPa compression stress in the concrete deck to make sure the concrete slab will not crack under traffic load in the operation period. Joint Epoxy is used for the joint between each segment. The material itself has a minimum compression strength of 60-70 MPa and serves a good function for segment connection. Although it takes time to daub when erection on site, it helps to enhance the durability of the joint. Each span has a 150 mm concrete wet joint as well. The concrete grade is the same as the precast elements. It is cast on site in case of segment cumulative misalignment. Prestress The approach bridges are fully externally prestressed in longi- tudinal direction; the maximum prestressing stress in the girder is about 12 MPa. For each kind of bridge, there are eight tendons in one span. They steer at the same longitudinal position and are anchored at a different height of anchorage block (fig. 5). For approach bridges with 6 × 30 m span arrangement, each tendon is composed with 25 strands of high strength steel strand for end span and 26 strands for middle span. The nominal area of each strand is 139 mm 2 and the design yielding stress of strand steel is 1860 MPa. For the girder top slab, there are transverse post-tensioned 3 4 5 thema Approach Bridge of Second Wuhu Bridge 3 2017 25 compared to previous similar bridge construction projects in China considering both the time and staff savings. Conclusion The approach bridge of the Second Bridge of Wuhu Yangtze River Highway Bridge is a good practice of industrialized construction. The whole project is scheduled to be finished in 2017. Application of precast segmental externally prestressed concrete bridge makes the design standard. Repetitive construction procedures reduce costs and construction time about 10 to 20 percent compared to traditional cast-in-place concrete girder scheme. Factory production enhances quality and minor site disruption. The project is a model for large- scale infrastructure construction (photo 7). ? Construction Precast The 20032 segments are cast in four casting yards with 90 cast cells. Steel rebar is assembled first at steel jigs in the cast yards. The details of steel cages are simulated accurately through CAD and the assembling sequence is optimized to ensure quality and speed of work. Then the segments are cast in the precast cells through short-line method?a new segment is match-cast against the preceding segment. A cycle time of one standard segment per day per casting cell can be achieved by steam curing. Transportation A cast segment is lifted and transported to the storage yard through gantry crane. Due to the time schedule and site constraints, double layer stacking is applied and the storage sequence is carefully planned to avoid additional lifting work (photo 6). The storage area is close to the bridge and the segments are transported within the right-of-way of the approach project. Erection Span-by?span erection is applied as the approach bridge construction method (photo 1). Both overhead gantry and underslung gantry are used in the project. A cycle time of five days per span can be achieved by overhead gantry, and 4 to 4.5 days per span by underslung gantry. Internet platform To ensure the efficiency and accuracy of the construction, an internet platform has developed. The platform stores and delivers all the information and is involved in both segment precast and erection. With the help of the internet platform, only one engi- neer needs to be prepared for data handling and the response time of checking and providing precast or erection coordinate is within 10 min. The work efficiency increased three times as 6 7 Approach Bridge of Second Wuhu Bridge 3 2017 26 thema 18000 (Sq.) Navigation channel 54600 Centre skew span C South Abutment Clearance envelope Vehicle parapet Reinforced concret e pilecaps Safety barrier Safety barrier L C North Abutment L 55.960(NWL) 57.300 58.200 58.960 17550 North span 17550 South span C North Pier L C South Pier L 55.300 55.300 Clearance envelope 33600 central between piers Lighting column Cables protected during construction Cables diverted/protecte d as required and agreed with WPD 57.300 49000 Clear skew span between banks Sheet pile wall to allo w construction of pier foundation 59.710 Steel-concrete composite flat arch bridge 1 The bridge design had to address a number of site specific chal- lenges as listed below: - accommodate a road alignment that would tie-in with Bedford Road Junction and the new campus; - span without any support in the River Channel (48.5 m min) and provide 18 m wide navigation channel with 3 m clearance above normal water level; As part of a new University Campus development in the city of Northampton (UK), a new road access bridge was required (photo 1 and 2). The aspirations and the planning requirements were set to keep the character of the existing landscape while creating an appropriate landmark structure for the new campus. The client's specimen design included a concrete flat arch bridge spanning 49 m with a shallow rise of 3.7 m above the navigable river. An alternative design was developed using a steel-con- crete composite structure solution for the deck. The awarded tender solution includes 220 tons of welded steel plates to form a shallow and flat arch structure. thema Steel-concrete composite fiat arch bridge 3 2017 27 18000 (Sq.) Navigation channel 54600 Centre skew span C South Abutment Clearance envelope Vehicle parapet Reinforced concret e pilecaps Safety barrier Safety barrier L C North Abutment L 55.960(NWL) 57.300 58.200 58.960 17550 North span 17550 South span C North Pier L C South Pier L 55.300 55.300 Clearance envelope 33600 central between piers Lighting column Cables protected during construction Cables diverted/protecte d as required and agreed with WPD 57.300 49000 Clear skew span between banks Sheet pile wall to allo w construction of pier foundation 59.710 - provide a clearance envelope beyond the navigation require- ments to meet the flood risk design criteria with a 1 in 200 years return period; - minimize disruption to the extensive number of buried services (11kV cables across the river, 33kV and 132kV in the North bank); - maintain river navigation during construction period; - minimal disruption to the river to maintain the ecology and biodiversity; - create a safe and pleasant pedestrian/cycle environment along the river banks; - address cost, statutory authority and build ability issues. Reference design scheme The client's engineer proposed an 89.7 m long structure comprising a single 49.0 m skew span concrete shallow arch structure supported at each river bank with 17.55 m approach span on each side connecting to the bridge abutments (fig. 3). Comparison of the shallow arch bridge in North ampton with other, similar span arch bridge structures is given in table 1. The proposed structure included a concrete ladder deck with deck beams supported on precast concrete arch ribs and forming balanced cantilever frames spanning from piled foun- dations on each bank (fig. 4). Tender design The constraints imposed by the planning documentation do not allow any deviation from the very flat arch requirements with a span to rise ratio of approximately 13. However, the geometry of the Riccardo Stroscio Tony Gee and Partners LLP 1 Steel-concrete composite flat arch