A new lower bound finite element method for slab analysis is presented as a practical substitute to full, non-linear, finite element methods that require expert knowledge and long running times. The method provides a general, safe and efficient lower bound solution for the analysis of reinforced concrete slabs up to failure. As it is finite element based, the method is more general than the yield line and strip methods currently in use. Furthermore, its lower bound nature makes it safer than the yield line method. The method uses a rotation-free, plate finite element modified to allow plastic "yield lines" to pass through at any direction. Yield lines are generated at the principal moment directions when the plastic moment capacity is attained. The material is assumed to be elastic perfectly-plastic. Following the general spirit of yield line analysis, the effects of a yield line are projected to the sides of the triangular element and then used to calculate the bending curvatures. The method's efficiency is achieved by using rotation-free plate elements with a single degree of freedom per node and by the incremental solution that does not require iterations. The method's accuracy and convergence are assessed by comparing standard cases with known results. In all cases, results were close to the theoretical values with difference of less than 1%. It is also used to solve a practical sized flat slab problem in order to demonstrate the method's efficiency, convergence, and speed.

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Between October 2003 and July 2004, Arup, in a joint venture with the Dutch airport planners NACO and the architects Foster & Partners, designed the Terminal and Ground Transportation Centre needed for the 2008 Olympic games at Beijing Airport. Work commenced on site in March 2004 and ended almost four years later with the opening ceremony in February 2008. This was the team's third airport together, the forerunners being Stansted Airport, London, in the late 1980s and Chek Lap Kok Airport, Hong Kong, in the late 1990s. For each terminal the basic engineering diagram is similar.The design of airport terminals is predominantly influenced by functionality. Externally, they are constrained by the movements of land transportation systems on one side and aircraft on the other. Internally, large numbers of people and baggage must flow from entrances to departure gates or arrivals gates to exits. Both the non‐public areas, like the baggage‐handling facilities, and the public areas need column‐free spaces to provide maximum flexibility and unimpeded passenger flow.Forces in roofs and floors increase with the square of the span and result in large member sizes, but these must be limited because the overall height of airport facilities is restricted. Furthermore, a deep roof structure will impair the ability for natural light to pass through the roof into the building's interior. Both requirements can only be achieved with a carefully integrated design.Airport terminals are characterized by the fact that the climatic and other physical conditions for which they must be designed vary across the world. For example, whereas Chek Lap Kok had to withstand typhoon wind loads and is located in a subtropical climate, Beijing is in an active seismic zone and experiences large seasonal temperature fluctuations. However, they must be able to accommodate the same aeroplanes worldwide while exhibiting their own form with respect to geometry, modularity, repetition and the use of information technology in the design, analysis, specification and fabrication.Today, fabrication technology is changing rapidly thanks to the application of computerized analysis and fabrication methods in engineering. This in turn influences the structural concept and design. A manifestation of this is illustrated below.

a urban Modelling group, school of civil, structural & Environmental Engineering, university college Dublin, Dublin, ireland; b faculty of Design, coburg university of Applied sciences, coburg, germany ABSTRACT A new, non-incremental advance in the lower bound finite element (FE) method for nonisotropic slab analysis is presented as a development of earlier work by the authors that was applicable only to isotropic slabs. The method provides a faster and simpler alternative to the full non-linear FE method in the non-linear analysis of slabs. Reinforced concrete was modelled as elastic perfectly plastic material, with rotation-free (RF) plate elements used to model slabs. They were modified to allow plastic yield lines to pass through elements satisfying non-isotropic yield conditions. Satisfying yield conditions and finding yield line directions differ significantly in their sophistication from their isotropic counterparts, as slab moment capacity is directiondependent and yield line direction does not coincide with principal moment direction. Yield line effects were projected to element sides then used in curvature calculations. Analysis was performed incrementally, with the slab considered to behave linearly within each load increment. As a result, no iterations were required to reduce the unbalanced forces, as the behaviour within each load increment was in equilibrium. Accuracy was assessed against benchmark examples, and generally was within 2.5% of yield line collapse loads.