Failure Assessment Of Floor Slab Systems Under Extreme Loading Conditions

多层建筑物可以承受各种形式的荷载，其中一些是常见和频繁的，但其他一些则更为极端和罕见。前一种类型包括构件和饰面的自重以及常规施加的荷载，例如由于居住者、家具、雪等引起的荷载。另一方面，后一种类型的荷载更严重，可能由大爆炸、重大火灾、强烈地震事件或这些效应的组合引起。显然，工程师必须在设计和建造建筑物时适当考虑结构在其整个生命周期中可能经历的不同荷载条件。然而，设计原理可以根据所考虑的载荷而显著变化。建筑物在承受常规荷载时，不会受到任何可能影响其功能的显著损坏，而极端事件设计的主要目的是防止不相称的倒塌和生命损失，即使是以大量的维修或更换成本为代价。本项目涉及极端荷载条件下建筑物结构的性能，重点是楼板的极限行为。防止建筑物中不成比例的连续倒塌的关键可能在很大程度上取决于楼板显著变形的能力，使得其可以通过膜机制而不是传统的弯曲强度来承载显著的载荷。这些膜机构对于极端情况下的承载能力至关重要，例如负载的意外增加（例如由于较高楼层的部分倒塌），实际跨度的增加（例如由于中间支撑元件（如梁或柱）的损失）或材料性能强度的降低（由于温度升高）。所有这些影响都可能发生在不同的情况下，或组合，意外加载scenaries. This项目的主要目的是评估极端荷载条件下的楼板的承载能力。本研究针对钢筋混凝土板及钢/混凝土组合板的受力性能进行了试验研究，重点研究了钢筋破坏的条件。测试将检查重要的几何特性、材料特性和边界条件的影响。实验结果将被用来验证一个分析程序，可以预测相应的变形和载荷水平的失败。最后，从测试和分析的结果将被用来生成简化的程序，可用于对极端负载情况下的楼板设计。还将通过一些实际例子说明详细和简化方法的适用性。拟议的研究将对英国和海外建筑业的安全和竞争力产生直接影响，从而通过提高结构安全性和有效使用建筑材料来提高生活质量。

Multi-storey buildings can be subjected to various forms of loading, some of which are of common and frequent nature but others are more extreme and infrequent. The former type includes the self weight of the members and finishes as well as conventional imposed loads such as those due to occupants, furniture, snow, etc. On the other hand, the latter and more severe type of loading can be caused by large explosions, major fires, strong seismic events, or a combination of these effects. Clearly, engineers have to design and construct buildings with appropriate consideration of the different loading conditions that may be experienced by the structure throughout its life cycle. However, the design philosophy can vary significantly depending on the loading under consideration. Whereas a structure is expected to resist conventional loads without suffering any notable damage that can affect its function, the main aim of design against extreme events is to prevent disproportionate collapse and loss of life even at the expense of a substantial repair or replacement cost.This project deals with the performance of building structures under extreme loading conditions, focusing on the ultimate behaviour of floor slabs. The key to preventing disproportionate progressive collapse in a building may largely depend on the ability of floor slabs to deform significantly such that it can carry significant loads through membrane mechanisms rather than conventional bending strength. These membrane mechanisms are vital for the load-carrying capacity in extreme situations such as an unexpected increase in load (e.g. due to the partial collapse of higher floors), increase in actual span (e.g. due to the loss of intermediate supporting elements such as beams or columns) or reduction in the strength in material properties (due to elevated temperature). All of these effects may take place under different, or a combination of, accidental loading scenarios.The main aim of this project is to assess the load-carrying capacity of floor slabs under extreme loading conditions. The research involves an experimental investigation into the performance of reinforced concrete and composite steel/concrete slabs, focusing on the failure condition causing fracture of reinforcement. The tests will examine the influence of important geometric properties, material characteristics and boundary conditions. The experimental results will be used to validate an analytical procedure which can predict the deformation and load levels corresponding to failure. Finally, the findings from the tests and analysis will be used to generate simplified procedures that can be used for the design of floor slabs against extreme loading scenarios. The applicability of the detailed and simplified approaches will also be demonstrated through a number of practical examples. The proposed research will have a direct impact on the safety and competitiveness of the building construction industry in the UK and overseas, consequently leading to a better quality of life through improved structural safety and the efficient use of construction materials.