RESIlient buildings using STainless steel (RESIST)

在火灾、爆炸和冲击等极端荷载下，建筑物能否存活的关键是提供坚固的结构框架，以适应由此产生的高强度和延展性要求。为此，梁-柱节点的性能至关重要，因为这些节点将受到高旋转能力要求和高束缚力的影响，因为它们需要促进悬链线的作用，并在支撑柱突然失效的情况下提供替代负载路径。支撑本研究项目的基本假设是，用具有更大延展性和更好的防火性能的适当等级的不锈钢代替连接关键部位的碳钢组件（例如螺栓，角夹板，板），将提高连接的强度和延展性，从而最大限度地抵抗极端事件（例如撞击，爆炸或火灾）的渐进倒塌。该项目包括4个技术工作包，第五个工作包致力于冲击和传播，如下所述：WP 1侧重于关节在冲击载荷下的行为。不锈钢板、螺栓和焊接材料将在高应变率下进行测试，以确定材料在冲击载荷下的响应。所获得的结果将用于校准明确考虑应变率敏感性的材料模型以及考虑应变率和应力三轴性影响的断裂模型。此外，搭接和t型桩将在高应变率下进行测试，FE模型将开发并用于参数化研究。wp2研究材料和连接在暴露于20至1000摄氏度高温下及其后的行为。板材、焊缝和螺栓材料将进行等温和非等温材料联片试验，而对于火灾后的情况，将考虑风冷和淬火。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，以建立火灾和火灾后条件下双腹板接缝、顶部和座角接缝以及扩展端板接缝的性能。WP3研究了静、动加载条件下单个节理在弯矩和剪切作用下以及双面节理在弯矩、剪切和拉伸作用下的行为。将生成物理试验和数值模型（利用WP1的研究结果）来描述在实际柱损失情况下的联合响应。还将对几何相同的传统钢接头进行补充数值研究，以比较新型碳/不锈钢混合接头与传统钢接头的性能。WP4将利用所有以前的WPs来开发和校准适合纳入使用梁单元的框架有限元模拟的弹簧接头模型。使用OpenSees，采用新型混合接头和传统接头的低、中、高层3D钢框架将在各种极端危险情况下进行分析，包括撞击和火灾，使用材料、几何形状和负载可变性的概率方法。所获得的结果将用于确定失效概率，导出分析脆性曲线，并量化采用新型连接对钢框架结构生存能力的影响。最后，WP5将利用所有以前的WPs来制定和传播设计指南，以最大限度地发挥研究的影响。与领先的咨询公司的密切合作以及与BSI的紧密联系，以及申请人对欧洲规范3的密切熟悉和参与，将确保研究成果迅速传播给相关实践、机构和规范发展机构。

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.