钢桁架连梁-联肢剪力墙耗能机理及抗震性能试验研究

对设置全钢桁架连梁和设置钢筋混凝土、钢桁架混合连梁的双层联肢剪力墙平面结构进行了拟动力试验和低周反复荷载试验,研究了不同工况地震波作用下剪力墙的时程响应,以及其破坏机理、承载力、滞回延性性能、耗能机理、刚度及强度退化机理。试验结果表明：全部设置钢桁架连梁的剪力墙的刚度分布合理,耗能机理及刚度强度退化机理符合联肢剪力墙抗震设计的要求。大震时,在保证较高耗能能力的同时能够维持较高的承载力和刚度,持续约束墙肢,抗震性能优于混凝土连梁联肢剪力墙体系,是一种较理想的连梁设置方案。     

Nonlinear seismic response analysis of reinforced concrete tube in tube structure

Super-highly reinforced concrete tube in tube structure is a developing structure system of high-rise building. The more reasonable derivation process of the multi-vertical-line-element model stiffness matrix is given.On the premise of pointing out the problems of present multi-spring element model, combined with present multivertical-line-element model for analyzing on shear wall, the model is expanded to spatial one, and the stiffness matrix of which is derived. Combined with hysteretic axial model and hysteretic shear model, it is suitable for columns,wall limbs and beams with all kinds of section form. Some examples are calculated and compared with test results,which shows that the models have relatively good accuracy. On the base of the experimental phenomenon and failure mechanism for tube in tube structure specimen, nonlinear seismic responses analysis program on the basis of the advantaged element model for tube in tube structure is developed. Calculation results are in good agreement with those of the pseudo-dynamic tests and the failure mechanism can be well reflected.     

地震作用下基础隔震框剪结构竖向连续倒塌可靠度分析

针对地震作用下RC串联滚轴隔震结构受力特征和损伤特点,提出适用于串联滚轴隔震结构柱的新型连接节点。通过开展1/2缩尺拟动力试验,研究采用新型连接节点的滚轴隔震结构柱在不同强度地震作用下的抗震性能。构造适用于滚轴隔震结构的一致危险设计谱,根据结构位移限值要求对滚轴隔震支座进行设计,通过数值模拟验证滚轴隔震支座的减震效果;结合不同超越概率的一致危险设计谱,分别选择地震波对装配式滚轴隔震结构柱进行拟动力试验研究,分析不同强度地震作用下装配柱和现浇柱的破坏形态、滞回曲线、刚度退化、耗能等抗震性能指标。研究结果表明：在超越概率为10%时,通过对非隔震结构柱和滚轴隔震结构柱进行数值模拟,计算得到剪力比为0.5,且通过试验研究发现,在超越概率为2%时,装配式滚轴隔震结构柱损伤指数为0.279,滚轴隔震支座发挥了良好的减震效果,装配柱在罕遇地震作用下发生轻微损伤;在超越概率为2%时,现浇柱最大裂缝宽度发展至1.8 mm,装配柱最大裂缝宽度发展至1.6 mm;对比骨架曲线、刚度退化、累积滞回耗能发现,装配柱承载力、初始刚度和累积滞回耗能较现浇柱略好。     

带中间柱摩擦阻尼器的装配式自复位钢框架拟动力试验

为解决较大跨度自复位钢框架结构层间位移角可能超限或耗能不足的关键问题,课题组前期提出将中间柱型阻尼器应用于装配式自复位钢框架。但是因门窗开洞等要求而不能在跨中处设置中间柱型阻尼器,从而提出了带双中间柱摩擦阻尼器的装配式自复位钢框架,对其进行了拟动力试验,并与带单中间柱摩擦阻尼器的装配式自复位钢框架的拟动力试验进行了对比,分析了其位移响应、滞回性能、中间柱摩擦阻尼器滑动、索力及典型部位应变变化等。结果表明,两榀框架震后短梁-长梁连接界面处残余转角和索力降低均较小,具有良好的开口闭合机制,耗能能力较优,能够有效避免主体结构的损伤,且带双中间柱摩擦阻尼器的装配式自复位钢框架控制结构侧移效果更好,耗能性能更优,适用于较大跨度的多高层结构。     

钢筋混凝土框架-剪力墙模型结构的拟动力试验研究

为进一步研究框架-剪力墙结构的抗震性能,以某大型火电厂7层7跨钢筋混凝土主厂房纵向框架-剪力墙结构体系的实际工程资料为背景,取几何缩尺比1∶8将原型结构转化为模型结构,分别通过不同地震水平的拟动力试验和伪静力试验对模型结构的开裂、屈服顺序、耗能能力、刚度退化、承载力、延性及变形性能等进行研究,分析了模型结构的破坏机理、受力特点、内力分布规律、结构的薄弱部位和动力反应。试验表明,模型结构的荷载-侧移滞回曲线饱满,耗能能力较好,具有良好的抗震性能,其破坏模式是剪力墙根部先屈服、随后梁端逐次出现塑性铰、最后柱根屈服;剪力墙对结构的承载能力和变形性能有较大影响,框架-剪力墙的协同工作随结构塑性变形的发展而变化。研究结果为此类结构的抗震设计提供了基础。     

基于频率退化的砌体房屋结构抗震性能评价

为研究双向地震作用下预制板砖砌体房屋结构的抗震性能评价方法,进行1∶2比例模型的双向拟动力试验。通过介绍试验中结构刚度和频率的变化,提出基于频率变化的抗震性能评价方法,评价结果与基于刚度退化的方法接近,但计算过程更加简捷。基于频率的评价结果与实际破坏状态也较吻合,说明该方法可以应用于预制板砖砌体房屋结构的抗震性能评价。     

框排架结构变形能力的试验研究及理论分析

针对工业厂房中框排架结构偏心、不规则的特点,以某火力发电厂主厂房为原型,建立整体结构的空间计算模型,分别进行模态分析和水平双向地震作用下的弹塑性时程分析,结合前期拟动力和伪静力试验研究,重点研究了该类结构的动力特性及整体的变形能力。研究结果表明:结构纵、横向刚度相差较大,扭转效应明显,且薄弱部位较多,在设计中应予以重视。     

Pseudo-dynamic analysis of overturning stability of retaining wall

A new method was presented to determine the safety factor of wall stability against overturning based on pseudo-dynamic approach. In this time-dependent method, the actual dynamic effect with variation of time and propagation of shear and primary wave velocities through the backfills was considered. Planar failure surface was considered behind the retaining wall. The results were compared with those obtained from Mononobe-Okabe theory. It is found that there is a higher value of safety factor by the present dynamic analysis. The effects of wall inclination, wall friction angle, soil friction angle and horizontal and vertical seismic coefficients on the overturning stability of retaining wall were investigated. The parametric study shows that both horizontal and vertical seismic accelerations have decreasing effect on the overturning stability of retaining wall.     

The Simulation of Impact Loads on Beam-type Structures using a Pseudo-dynamic Procedure

Abstract:  This study proposes an alternate method for the analysis of beams with solid cross-section or built as a framed structure and subjected to transverse impact loads from an external striker. The procedure used in the analysis is a combination of two essential tools using pseudo-dynamic techniques. The method reported here involves only one degree of freedom for the structure modelling and assumes an elastic contact between an external striker and the beam structure, which in reality does not happen. As only one degree of freedom is considered in the analysis, some important limitations are inherent to the method proposed here. Essentially, there is the difficulty of modelling the displacement field associated with the transient structure behaviour accurately, as a consequence of fast-rate impact loads. Another difficulty faced by the method refers to a local structure behaviour associated with contact loads. The present method can deal with large displacements in transversely loaded beams associated to a collapse mechanism having a simple geometry and defined with precision from a single parameter. This ensures reasonable accuracy in the evaluation of the strain energy absorbing capacity of transversely impacted beam structures using a single degree of freedom model in a pseudo-dynamic procedure.     

循环荷载作用下软土中吸力锚变形过程拟动力算法

针对静荷载与循环荷载共同作用下软土中张紧式吸力锚的变形失稳过程进行了研究,通过拟动力有限元法模拟了静荷载和循环荷载共同作用下模型锚变形过程,验证了拟动力算法的可行性。分析过程中采用考虑循环荷载作用历史的等效线性黏弹性计算模型描述饱和软黏土不排水循环动力响应,依据蠕变理论描述土单元的循环累积应变响应。基于ABAQUS有限元软件,借助拟动力黏弹塑性模型提出了一种既能描述土体循环动力响应又能获得土体变形循环累积过程的拟动力算法。通过编制脚本程序PYTHON,将计算土体循环动力响应的过程与分析土体变形累积的过程连接起来,使计算机自动完成整个拟动力有限元算法的分析过程,最终实现了不通过详细跟踪循环荷载作用历史即可获得软土中吸力锚在循环荷载作用下变形逐渐循环累积至失稳过程的拟动力算法。