RESIlient buildings using STainless steel (RESIST)

建筑物承受极端荷载（如火灾、爆炸和冲击）的关键是提供坚固的结构框架，以满足由此产生的高强度和延展性要求。为此，梁柱接头的性能至关重要，因为这些接头将承受高旋转能力需求和高系紧力，因为它们需要促进悬链线作用并在支柱突然失效的情况下提供替代载荷路径。支撑这项研究项目的基本假设是，在节点的关键部位更换碳钢组件，（例如，螺栓、角楔、板）与具有更大延展性以及更好耐火性能的适当等级的不锈钢的接合将增强接合强度和延展性，从而最大化在极端事件（例如冲击）期间对逐渐倒塌的抵抗力，该项目由4个技术工作包组成，第五个工作包致力于影响和传播，如下所述：WP 1侧重于冲击载荷下接头的行为。不锈钢板、螺栓和焊接材料试样将在高应变率下进行测试，以确定材料在冲击载荷条件下的反应。所得到的结果将被用来校准材料模型明确占应变率敏感性以及断裂模型考虑应变率和应力三轴性的影响。此外，搭接接头和T型接头将在高应变率下进行测试，并将开发有限元模型，用于参数研究WP 2研究材料和连接在暴露于20至1000摄氏度高温下及之后的行为。将对板材、焊接和螺栓材料进行等温和非等温材料试样测试，而对于火灾后条件，将考虑空气冷却和淬火。在确定温度对材料响应的影响后，将开发先进的有限元模型，以确定火灾条件下和火灾后双腹板夹板、顶部和底部角夹板和延伸端板节点的性能。WP 3研究了在静态和动态荷载条件下，弯矩和剪力下的单个节点以及弯矩、剪力和张力下的双侧节点的行为。将生成物理测试和数值模型（利用WP 1的结果），以模拟实际柱损失情景下的联合响应。还将对几何形状相同的传统钢节点进行补充数值研究，以比较新型混合碳/不锈钢和传统钢节点的性能。WP 4将利用所有以前的WP开发和校准弹簧节点模型，适用于使用梁单元进行框架有限元模拟。使用OpenSees，低，中，高层3D钢框架采用新型混合节点以及传统的将分析各种极端危险的情况下，包括使用概率方法的材料，几何形状和负载的可变性的影响和火灾。所获得的结果将被用来确定故障的概率，并推导出分析脆弱性曲线和量化的影响，采用新的连接对钢框架结构的生存能力。最后，WP 5将利用所有以前的WP来开发和传播设计指南，以最大限度地发挥研究的影响。与领先顾问的密切合作和与BSI的紧密联系，以及申请人对Eurocode 3的密切了解和参与，将确保研究结果迅速传播到相关实践，机构和代码开发机构。

Key to the survival of a building subjected to extreme loads, such as fire, blast and impact is the provision of a robust structural frame, which can accommodate the resulting high strength and ductility demands. To this end, the performance of the beam-to-column joints is paramount, since these will be subjected to high rotation capacity demands and high tying forces, as they are required to facilitate catenary action and provide an alternative load path in the case of a sudden failure of a supporting column. The fundamental hypothesis underpinning this research project is that replacing the carbon steel components in critical parts of the joints (e.g. bolts, angle cleats, plates) with an appropriate grade of stainless steel, which has greater ductility, as well as better fire behaviour, will enhance the joint strength and ductility thus maximizing the resistance to a progressive collapse during an extreme event such as an impact, blast or fire.The project consists of 4 technical work packages with a fifth one dedicated to impact and dissemination, as outlined hereafter:WP 1 focuses on the behaviour of joints under impact loading. Stainless steel plate, bolt and weld material coupons will be tested under high strain rates to determine the material response under conditions brought about by impact loading. The obtained results will be utilised to calibrate material models explicitly accounting for strain rate sensitivity as well as fracture models considering the effect of strain rate and stress triaxiality. Furthermore, lap joints and T-stubs will be tested at high strain rates and FE models will be developed and utilised in parametric studiesWP2 studies the behaviour of material and connections at and after exposure to high temperatures ranging from 20 to 1000 degrees centigrade. Isothermal and anisothermal material coupon tests will be conducted on plate, weld and bolt material, whilst for the post fire condition, both air cooling and quenching will be considered. Upon determining the effect of temperature on material response, advanced FE models will be developed to establish the performance of double web cleat, top and seat angle cleat and extended endplate joints under and post fire conditions.WP3 investigates the behaviour of individual joints under moment and shear and double sided joints under moment, shear and tension under static and dynamic loading conditions. Both physical tests and numerical models (utilising the findings of WP1) will be generated to characterise the joint response under realistic column loss scenarios. Supplementary numerical studies on geometrically identical conventional steel joints will also be conducted to compare the performance of the novel hybrid carbon/stainless steel and conventional steel joints.WP4 will utilise all previous WPs to develop and calibrate spring joint models suitable for incorporation into FE simulations of frames using beam elements. Using OpenSees, low-, medium- and high-rise 3D steel frames employing the novel hybrid joints as well as conventional ones will be analysed under a variety of extreme hazard scenaria including impact and fire using a probabilistic approach for the variability in material, geometry and loading. The obtained results will be utilised to determine the probability of failure and derive analytical fragility curves and quantify the effect of the adoption of the novel connections on the survivability of steel framed structures. Finally, WP5 will utilise all previous WPs to develop and disseminate design guidance to maximise the impact of the research. The close collaboration with leading consultants and strong links with BSI, as well as the applicants' close familiarity and involvement with Eurocode 3 will guarantee prompt dissemination of the research findings to the relevant practices, institutions and code development bodies.