基于动力可靠性分析的滑移隔震体系的优化设计

本文探讨了滑移隔震体系在零均值高斯白噪声地震作用下的优化设计问题,首先利用编译等效线性化方法并按首次超超损坏泊松过程模型的双壁问题得到质点的滑移可靠性函数,然后采用拉格朗日乘子法进行了该滑移隔震体系基于动力可靠性分析的优化设计。     

基础隔震结构的非线性动力分析

新的建筑抗震设计规范将隔震结构列入其中，探讨分析了结构基础隔震应用中应注意的问题，提出了非线性动力时程分析计算模型并编制了程序。借助该程序，分析了基础隔震结构在地震作用下的层间位移、加速度和剪力等地震反应并与未隔震相同结构建筑的地震反应进行了对比。     

恢复力—摩擦基底隔震结构的地震可靠性分析

本文建立了恢复力-摩擦基底隔震结构在地震作用下的运动微分方程。地震地面运动被模拟成随机过程。利用等效线性化方法,获得了这种基底隔震结构在地震作用下的均方位移和均方速度反应。根据最大位侈反应的概率分布函数,求得了这种基底隔震结构和与它相应的基底固定结构在给定地震作用下的破坏概率。计算结果表明,这种基底隔震结构在地震作用下有较高的可靠性。     

基底滑移隔震刚性结构的随机滑移反应和可靠性分析

本文使用Fokker-Planck方程,给出了基底可滑移刚体在高斯白噪声扰动作用下的滑动速度概率密度函数。利用等效线性化方法,求得了基底可滑移刚体在有限带宽白噪声扰动作用下的均方滑动位移反应和均方滑动速度反应。进而给出了基底滑移隔震刚性房屋滑离基础的滑离概率,并导出了基础附加宽度的计算公式。     

大震下被动与智能隔震结构动力可靠度的对比

对被动及智能隔震结构在“大震”条件下的动力可靠度进行探讨。将被动及智能隔震体系均取作弹塑性模型,并用退化Bouc-W en滞变模型描述上部结构的恢复力,用非退化Bouc-W en模型描述隔震层的恢复力。采用虚拟激励法计算结构的随机响应,根据我国抗震规范中“大震不倒”的设防目标,采用各层最大层间位移峰值响应和累积滞变耗能构造双参数的随机疲劳累积损伤指数,作为功能状态指标。假定各层失效相关,用串联系统计算体系动力可靠度。通过数值算例,对比了被动隔震、智能隔震与非隔震体系的条件失效概率,从动力可靠度角度显示了智能隔震体系的减震优势。     

悬摆隔震结构动力分析方法初探

本文对悬摆隔震结构力学模型作等效处理,探索利用常规计算程序对其进行动力分析的有效方法,同时验证了悬摆隔震指施对于减弱结构地震反应的效果是明显的。     

土-桩-隔震结构非线性动力相互作用分析方法综述

近年来,土-桩-隔震结构非线性动力相互作用成为结构抗震领域热点研究问题之一。首先,在回顾现有土-桩-隔震结构非线性动力相互作用研究的基础上,分析国内外学者针对土-桩-隔震结构动力相互作用采用的主要分析方法,包括理论分析法、整体时程分析法、模型试验法及能量分析法;然后,系统地总结了目前考虑土-结构相互作用的隔震结构动力反应相关研究成果;最后,分析了现有研究存在的不足及亟待解决的问题,并给出相关研究建议。     

隔震结构"小震不坏"的动力可靠度分析

本文探讨叠层橡胶隔震体系在“小震不坏”条件下的动力可靠度分析。基于等效线性化的隔震工程设计参数,建立非比例阻尼隔震结构模型。采用双过滤白噪声功率谱模型描述地震动,并用林家浩虚拟激励法进行随机响应分析。以各层的最大层间位移响应作为控制指标,取结构的弹性位移限值作为位移极限值,建立功能状态方程。根据一次二阶矩方法,用串联模式计算体系的总体可靠度。文末选用了一个7层隔震框架作为数值算例,探讨了隔震阻尼、寒冷环境、节点构造误差所引起的隔震层刚度上升,以及场地土类别等对体系动力可靠性的影响。     

滑移隔震结构的抗风稳定性分析

滑移隔震结构要求在风荷载作用下保持安定。应用多种方法研究了不同摩擦系数、不同基本风压作用下滑移隔震体系的抗风稳定性：（1）考虑一阶振型的等效静力法;（2）采用谐波合成法模拟近似的具有给定功率谱密度函数的脉动风,作用于结构上,进行动力时程分析;（3）根据风压的功率谱密度函数计算脉动风压的概率法。研究结果表明时程分析法与概率法得到的风荷载相近,大于等效静力法得到的风荷载。摩擦系数为0.1可以满足基本风压小于0.90kN／m^2地区滑移隔震结构的抗风稳定性。     

一座空旷砖混厂房结构的隔震加固

介绍一栋砖混单层厂房的隔震加固方案，对加固后结构与原结构的地震反应作了对比分析，分析结果表明隔震加固大大提高了原结构的抗震性能。对加固所用的隔震支座性能作了具体分析，提供了支座的设计与试验对比结果，并对砌体结构隔震加固中采用的“夹梁托墙”技术的可行性作了试验研究，结果表明：支座的设计分析结果与试验结果吻合较好，夹梁具有良好的工作性能。     

Control of structures with friction controllable sliding isolation bearings

A friction controllable sliding isolation system was developed and experimentally and analytically investigated by Feng et al. (Feng, Q., Shinozuka, M. & Fujii, S. A. friction controllable sliding isolation system. J. Eng. Mech., ASCE, 1993, 119(6), in press), the control algorithm having been developed based on a key assumption that the structural motion is always in the sliding phase. However, this assumption may not be valid in cases where the sticking phase of the structural motion dominates. In this paper a new control algorithm is developed including the effects of stick—slip phases. Effect of time delay is included in the formulation. The developed algorithm is used to evaluate the accuracy and limitations of the algorithm with continuous sliding assumption. Response to various earthquake motions, simulated using the two control algorithms, is presented. Comparisons with experimental results are also presented. Effects of stick—slip phases on the response are evaluated.     

基于动力可靠度的隔震结构参数模糊优化

分别选取Bouc—Wen和退化Bouc—Wen模型描述隔震层及上部结构滞变回复力，采用虚拟激励法进行隔震结构随机响应分析。用各层最大层间位移响应和累计疲劳损伤指数建立双参数的功能状态方程，用一次二阶矩理论计算隔震结构失效概率。选用一个隔震框架作为数值算例，探讨了低频过滤器、隔震阻尼比和隔震刚度对隔震结构各子系统条件失效概率的影响。建立了隔震结构参数多目标优化模型，用失效概率确定单因素评判的隶属度，并采用最大隶属度法对隔震参数进行模糊优化。     

Extreme value distribution and reliability of nonlinear stochastic structures

A new approach to evaluate the extreme value distribution （EVD） of the response and reliability of general multi-DOF nonlinear stochastic structures is proposed. The approach is based on the recently developed probability density evolution method, which enables the instantaneous probability density functions of the stochastic responses to be captured. In the proposed method, a virtual stochastic process is first constructed to satisfy the condition that the extreme value of the response equals the value of the constructed process at a certain instant of time. The probability density evolution method is then applied to evaluate the instantaneous probability density function of the response, yielding the EVD. The reliability is therefore available through a simple integration over the safe domain. A numerical algorithm is developed using the Number Theoretical Method to select the discretized representative points. Further, a hyper-ball is imposed to sieve the points from the preceding point set in the hypercube. In the numerical examples, the EVD of random variables is evaluated and compared with the analytical solution. A frame structure is analyzed to capture the EVD of the response and the dynamic reliability. The investigations indicate that the proposed approach provides reasonable accuracy and efficiency.     

随机结构动力可靠度估计算法的对比分析

对比分析了随机结构动力可靠度计算的三种估计算法.渐进展开法是基于Laplace算法对概率积分进行渐进估计的,此法通过计算最大被积分式值对应点,并将其代入概率积分的渐进估计表达式求解失效概率.由于概率积分的主要贡献来自于最大被积分式值对应点的周围,因此本文的重要抽样法假定重要抽样函数的最大似然值等于最大被积分式值对应点值.极值分布-泰勒展开法首先通过结构随机参数的极值分布函数给出失效概率的表达式,随后利用泰勒展开法对失效概率进行估计,其中采用中心差分法对极值分布函数的梯度进行估算.最后应用三种算法和Monte Carlo法对受高斯白噪声激励作用的单自由度随机结构进行了计算,结果表明三种方法不但运算简便,而且对比Monte Carlo法计算效率有显著提高.     

基础滑移隔震结构振动特性分析

通过对基础滑移隔震体系等代模型自振特性的分析，就多自由度剪切型隔震结构振动特性进行了较为全面的探讨，从而为滑移隔震结构的动力计算建立了合理的理论依据。     

带TMD的结构基于动力可靠性约束的优化设计

本文在运用复模态法求得多自由度带TMD结构随机地震响应解析解的基础上．采用基于动力可靠性约束的优化设计方法对TMD装置参数的优化取值进行了系统研究,以结构最大位移响应的期望值为目标函数,以TMD装置响应的动力可靠性为约束条件,运用罚函数法获得到TMD装置的优化设计参数．并给出了算例,从而建立了带TMD结构基于动力可靠性约束的抗震优化设计的一整套方法,本文方法也可用于基础隔震结构、带TLD减震结构以及带TMD和TLD抗风结构的优化设计。     

基于复振型分解的多自由度非线性体系动力可靠性研究

提出了基于复模态理论的多自由度非线性体系动力可靠性分析方法。该方法首先采用等效线性化的方法处理体系的非线性问题,然后采用复模态分析处理非经典的等效线性阻尼矩阵,将具有非经典阻尼的等效多自由度线性体系按复振型分解,将多自由度体系的随机反应分解为一系列一阶体系的复模态反应,从而求得体系的随机反应,最后进行体系的动力可靠度计算。通过算例验证,表明该方法概念明确、思路清晰,为一般多自由度非线性体系提供了一个普遍适用的动力可靠性分析方法。     

Smart restorable sliding base isolation system

A modern base isolation system is proposed for the aseismic control of structures. It is composed of steel-Teflon Flat Sliding Bearings, to support the gravity loads while allowing large horizontal displacements, and simply connected Shape Memory Alloy (SMA) truss elements, to provide the necessary horizontal stiffness as well as a proper restoring capability. The system is referred to as Smart Restorable Sliding Base Isolation System (SRSBIS). Depending on the arrangement of the auxiliary SMA elements, SRSBIS can exhibit a geometric nonlinearity in addition to the nonlinearity of materials. In this paper, the dynamic characteristics of SRSBIS are first examined in terms of the force-displacement behavior, effective period of vibration, and equivalent damping. After that, the earthquake response of buildings equipped with SRSBIS, designed in accordance with a direct displacement-based approach, is evaluated through extensive nonlinear time-history analyses. The effects of the design parameters on the system behavior are then investigated within a comprehensive parametric study and the seismic performances of SRSBIS are finally compared to those of similar practical isolation systems. Based on the results, it is shown that SRSBIS can be suitably used for the seismic protection of structures.     

Characterizing friction in sliding isolation bearings

The force–displacement behavior of the Friction Pendulum? (FP) bearing is a function of the coefficient of sliding friction, axial load on the bearing and effective radius of the sliding surface. The coefficient of friction varies during the course of an earthquake with sliding velocity, axial pressure and temperature at the sliding surface. The velocity and axial pressure on the bearing depend on the response of the superstructure to the earthquake shaking. The temperature at an instant in time during earthquake shaking is a function of the histories of the coefficient of friction, sliding velocity and axial pressure, and the travel path of the slider on the sliding surface. A unified framework accommodating the complex interdependence of the coefficient of friction, sliding velocity, axial pressure and temperature is presented for implementation in nonlinear response‐history analysis. Expressions to define the relationship between the coefficient of friction and sliding velocity, axial pressure, and temperature are proposed, based on available experimental data. Response‐history analyses are performed on FP bearings with a range of geometrical and liner mechanical properties and static axial pressure. Friction is described using five different models that consider the dependence of the coefficient of friction on axial pressure, sliding velocity and temperature. Frictional heating is the most important factor that influences the maximum displacement of the isolation system and floor spectral demands if the static axial pressure is high. Isolation system displacements are not significantly affected by considerations of the influence of axial pressure and velocity on the coefficient of friction. Copyright © 2014 John Wiley & Sons, Ltd.