强震下高层建筑非线性反应模拟关键问题研究

The high-rise buildings are playing more and more important role in the fast growing of urban area of China. This offered a great motivation on research activities about the safety of the high-rise building under great earthquake as many economic active areas in China are also seismic active areas. This project sets high-rise buildings as the objects of study, and aims at developing an accomplished simulation method and platform in response of high-rise buildings during strong earthquake. Firstly, in terms of improving the hackneyed and incomplete plane cross section assumption in analyzing shear-wall models, new shear-wall elements, as well as the element stiffness matrix, based on curved cross-sections, can be erected, forming new shear-wall models. Secondly, by recompiling the solving framework of finite element method, different solvers can be utilized for solving element stiffness matrix and structural stiffness matrix, reconciling the contradiction between solutions of the linear method of explicit analyses and of the iteration method for force-based elements. Meanwhile, parallel computing can be used to accelerate the calculation, realizing the numeral solving technique for high-rise buildings with a more rapid, more effective and more stable computations. And based on simulation method, integrated and visualized platform will be exploited. With the simulation method, platform, and the technique combining earthquake damage survey, experimental study, and finite element method, study of high-rise building’s failure mechanism under strong earthquakes will be made.

我国处在经济建设高速发展的时期，高层建筑大量涌现，确保高层建筑在遭受罕遇地震后的安全具有重要意义。本项目拟研究高层建筑非线性分析中的关键问题，并发展一套模拟方法及分析平台，提供高层非线性模拟工具。首先重点解决现有剪力墙分析模型中平截面假定在非线性阶段和实际不符的问题，构造新的横截面为曲面的剪力墙单元，开发出适用于大变形的新型剪力墙单元模型，提供理论基础、工作机理和模拟效果。然后，解决单元刚度矩阵求解和结构刚度矩阵求解采用不同求解器，进而达到协调显式分析方法线性求解和基于力插值梁柱单元内部需要迭代求解的矛盾；同时采用并行计算提高计算速度，实现快速、高效、稳定计算的高层建筑非线性数值求解技术。在模拟方法研究的基础上，开发集成化、图形化的分析平台。借助于模拟方法和平台，选择典型高层结构，采用震害分析、试验研究和有限元数值分析相结合的技术手段，深入研究高层建筑在强地震作用下的破坏机理、特性和规律。

为了保证强震作用下高层建筑结构安全，必须加强强震下结构抗震性能的研究。然而目前高层建筑在强震下的模拟方法在很多方面还存在问题，如剪力墙非线性分析模型不成熟；强非线性在计算中容易迭代不收敛而中止导致不能得到计算结果等。为了搭建一套可行的高层建筑模拟方法及分析平台，本项目展开了如下研究：.1、取某11层高层建筑的底部两层剪力墙，按照1:2缩尺，完成了两个1:2大比例尺的剪力墙拟静力倒塌试验，研究了其破坏形态、滞回特性、变形能力、耗能能力、截面应变等。.2、提出了考虑截面剪切变形的修正基于力插值纤维单元（MFBFE），其截面不再是平截面，而是曲面，用于模拟剪力墙和连梁的地震反应非线性分析，从截面层次上建议了一种针对连系梁MFBFE单元的剪切滞回模型。算例分析结果表明，分析结果与试验结果吻合较好，成功预测了构件的初始刚度、屈服力、极限力、卸载刚度、残余位移、延性和能量耗散。.3、对隐式方法和显式方法进行了对比分析。实例分析表明，从计算精度来讲，隐式方法和显式方法都能得到较好的精度。从计算效率来讲，对于自由度较少的小型结构，隐式方法计算效率远远高于显式方法；对于自由度庞大的大型结构，显式方法计算效率高于隐式方法。建议处理自由度多的高层建筑弹塑性分析时，采用显式分析方法。.4、基于tcl/tk语言开发了跨平台交互式图形用户界面软件ViPSea（Visual Interaction Program for structural engineering analysis），它采用交互式的图形建模、调用OpenSees计算以及结果图形显示模式，因此可以实时动态的显示分析过程和结构反应。.5、采用VipSea程序对汶川地震中破坏严重的都江堰市电信大楼进行逐步增量时程分析（IDA）。IDA分析结果显示底层和9层是薄弱层，而底层由于各指标基本都为最大值，因此将首先出现破坏，这与震害调查结果基本相符。