振动台试验是高层及复杂结构抗震性能研究的一种重要手段.微粒混凝土是振动台试验模型中用来模拟混凝土的一种基本材料,其性能直接影响振动台试验结果的准确性.本文通过17组不同配比微粒混凝土试块的力学性能试验,研究了水灰比、灰砂比、砂的级配、外加剂等因素对其力学性能关键指标(弹性模量、抗压强度)的影响,并结合试验结果提出了调整配比的方法,研究结果可为振动台试验模型用微粒混凝土的试配提供指导.

对成都绿地T1塔楼1:35缩尺模型进行振动台试验研究,测试了模型结构在7.5度多遇、设防、罕遇及8度罕遇地震作用下的动力特性、加速度反应、位移反应、关键部位的动应变反应,检验了结构的抗震性能,并将振动台试验结果与Etabs模拟结果进行对比.结果表明:成都绿地中心项目工程主楼工程结构设计合理,能够满足规范要求,原结构总体可达到预设的抗震设计性能目标.

为了得到采用钢筋-砂浆面层交叉条带法加固砌体结构缩尺模型试件的破坏形态,评价其抗震储备能力,对经历地震模拟振动台试验后的模型试件进行了拟静力试验研究,分析了试件的破坏形态、荷载和位移特征,基于Pushover方法评价了试件的抗震能力.结果表明:试件的破坏模式为窗间墙体交叉条带附近开裂破坏,未形成贯通交叉裂缝,交叉条带法加固可有效改善窗间墙体的破坏形态;试件具有较好的变形能力和延性;对振动台试验后未破坏的试件采用拟静力试验方法再次进行试验的综合试验方法是可行的.

大跨屋盖体系中存在大量的正在服役使用的网格结构,其鉴定、诊断、加固、维修技术已成为加固技术研究的热点之一.网格结构加固中常常会遇到杆件的强度满足要求而稳定性不满足要求的问题.常规的替换杆件加固法或焊接增大截面加固法均存在施工风险大、工期长的问题.为减少对建筑使用功能影响,负载条件下进行加固并尽量减少施工现场作业成为网格结构压杆稳定性加固中亟待解决的问题.结合某屋盖网格结构加固工程,课题组提出了一种解决网格结构压杆稳定性不足的套管加固法,采用屈曲-接触力学理论推导和试验校核相结合的方法,针对加固后不同的破坏机理,建立相应的力学模型,分析内管及套管的屈曲变形特征、接触传力机制及套管与内管的共同工作机理.在此基础上提出套管加固后压杆稳定承载力的计算公式,为工程应用及规范制定提供科学依据.套管加固法减少了网架结构加固中的杆件拆除及焊接作业,降低施工风险,缩短施工作业时间,取得了良好的社会与经济效益,可为类似改造工程提供借鉴.

Replacement section method with high strength concrete is a direct reinforcement method,It is usually used to bearing structure which has lower concrete strength at compression area or serious defect,the method mainly compensate concrete strength to low bearing,at last to low the axial compression ratio of column.In this article,we do a new test research,The column which was destroyed under quasi-static cyclic test is reinforcement with this method to do the second same test,then we get specific parameters of anti-seismic performance from the test in order to research feasibility,applicability and limitations on this method.

Through two prototype check bar,the prestress of steel strand in the concrete during unbonded prestress stretch-draw construction,prestress loss and prestress distribute in the concrete tube wall,as well as the prestress distribute in the concrete tube wall in full water are all researched.Result shows that,when one end being stretched,prestress loss of single circle prestressing tendon arrangement pipe is smaller than two circle tendon arrangement;after pulling construction,concrete pipe form close pressure loop,which can increase anti-crack performance of concrete culvert pipe;tensile strength more bigger than stress produced by 1.0MP hydraulic pressure.

The improved Hilbert-Huang transform(HHT),coupled with the random decrement technique(RDT),is been proposed in this study to analyze the wind-induced responses of Shanghai Jin Mao Tower with height of 420.5m under wind-force of 7～9 grades,so the first and second natural frequencies and the corresponding damping ratios are obtained in its east-west and north-south direction.To avoid the mode mixing problems in the identification process,the Butterworth band-pass filter is then taken into account to filter the field measurement data of acceleration responses.Numerical results reveal that the first frequency in both directions is almost identical,but the second frequency in the north-south direction is greater than that in the west-east direction.Additionally,the damping ratio of Shanghai Jin Mao Tower is less than that of material itself.Likewise, with the modal order increasing,the standard deviations of the identified damping ratios increase.These findings will give a reference to the wind-resistant design and construction of super high buildings in the future.Simultaneously,numerical results also indicted that the improved HHT,coupled with both the RDT and Butterworth band-pass filter,is able to identify the modal parameters of super high buildings commendably and effectively.