高层建筑与相邻多层建筑间的动力相互作用

本文阐述了高层建筑与相邻多层建筑间的动力相互作用问题,应用波动理论,采用二维显式有限元的方法对这个问题进行了分析,通过实例计算得到一些有益的结论,如高导建筑对相邻多层建筑影响较大;竖向反应影响比水平方面影响大;这种影随着距离的增大而减少等。     

基于建筑物易损性分类的群体震害预测方法研究

本文以多层钢筋混凝土结构为例,根据收集到的震害预测单体样本对多层钢筋混凝土结构按年代、层数、用途进行归类分析,给出了不同分类下的多层钢筋混凝土结构的易损性矩阵。由房屋抗震性能普查资料统计出的不同分类建筑物的面积比例,与不同分类建筑物易损性矩阵进行加权平均,建立具体预测区的建筑物易损性矩阵。最后以西安市阎良区为例,利用本文方法给出了阎良区多层钢筋混凝土结构的易损性矩阵。并与传统的震害预测方法对比,证明该方法的可行性,以及较高的可靠性。该方法思路简洁,操作方便快捷,是震后快速评估的有效方法。     

建筑结构基础隔震分析

本文详细地阐述了基础隔震的基本原理与特性,分析了隔震体系的类型及其特点。提出了隔震结构基于位移设计的设计指标和设计准则,并给出了设计步骤和实例。     

Analytical prediction of experimental building pounding

Valuable insights on the problem of seismic pounding have been obtained recently from analytical studies. So far, the proposed analytical models have not been validated experimentally. This paper presents the results of shake table tests of pounding between adjacent three- and eight-storey single-bay steel framed model structures. The pounding response of the frames was measured for various earthquake intensities and initial separations. The experimental results were compared to the predictions resulting from two existing pounding analysis programs. The solution strategy of the first program, SLAM-2, is based on a modal superposition technique. The second program, PC-ANSR, is a non-linear time-step analysis code in which an elastic gap element has been included. Modelling the pounding effect by elastic gap elements in the two programs produced accurate displacement and impact force results. Amplitudes of short acceleration pulses were not well predicted, however, for practical time-step increments. Relative rotations between adjacent floors induced grinding contacts which cannot be captured by uni-axial gap elements.     

Seismic analysis of a building block

This paper reports on the study of the seismic response of an urban building block located in Faial, a town of the Horta Island of the Azores, Portugal. The work fits within the framework of studying strengthening schemes suitable for the reconstruction process of a town damaged by an earthquake action and includes numerical modelling of all the building blocks with calibration of material and structural parameters based on ambient vibration tests. The study aims at understanding a number of issues that are likely to influence the global behaviour of the block and the local response of individual buildings, namely the group effect of adjacent constructions, the in-plane stiffness of floors and/or roofs and the presence of possible localized strengthening interventions in selected parts of the block.     

Persisting challenges for performance-based building assessment

Intense research and refinement of the tools used in performance-based seismic engineering have been made,but the maturity and accuracy of these methods have not been adequately confirmed with actual data from the field. The gap between the assumed characteristics of actual building systems and their idealized counterparts used for analysis is wide. When the randomly distributed flaws in buildings as they exist in urban areas and the extreme variability of ground motion patterns combine,the conventional procedures used for pushover or dynamic response history analyses seem to fall short of reconciling the differences between calculated and observed damage. For emergency planning and loss modeling purposes,such discrepancies are factors that must be borne in mind. Two relevant examples are provided herein. These examples demonstrate that consensus-based analytical guidelines also require well-idealized building models that do not lend themselves to reasonably manageable representations from field data. As a corollary,loss modeling techniques,e.g.,used for insurance purposes,must undergo further development and improvement.     

Overturning effects in stiffened building frames

In this paper seismically induced overturning effects in stiffened building frames are studied by examining the response of two structures: a 20-storey ‘core wall’ reinforced concrete frame and a 10-storey steel braced frame. The excitations utilized in the study are the 1971 Pacoima Dam S16E Record and the 1940 El Centro N-S Record magnified by a factor of two. Non-linear effects of the following types are considered: plastic hinging of beams and columns, yielding and/or buckling of bracing members and transient uplift of portions of the structures from the foundation. In particular, comparisions are made between response with unlimited base overturning capacity assumed and response with dead-weight overturning resistance only. Providing dead-weight overturning resistance only is shown to significantly reduce seismic load levels, with relatively little or no loss in drift control. Ductility demand in these stiffened frames is shown to be limited, when transient uplift is allowed, to the link beams connecting stiffened and unstiffened portions of the structures.     

应用基础隔震技术的建筑工程造价分析

应用叠层橡胶支座进行基础隔震是目前国内外大力推广的一门建筑抗震新技术。但由于对采用隔震技术后建筑物的工程造价是否会增加缺乏具体的经济技术指标,使得建筑开发商对其推广应用一直持保守态度。选择了位于VIII度区的两个典型工程实例(一例为乙类建筑,另一例为丙类建筑),简要分析了同一建筑物采取不同设计方案(不隔震但抗震设防、隔震使实际设防水平提高、隔震后与未隔震建筑保持相同设防水平等三种不同设计方案)对工程造价的影响及差异。分析数据表明,在同等设防烈度下,基础隔震技术的合理应用可以使被隔震建筑的工程造价与同条件只采用抗震设防的建筑工程造价适当降低。     

Torsional mechanisms in ductile building systems

It is postulated that in order to estimate torsional effects on the seismic response of ductile building structures, the associated plastic mechanism to be developed in the three-dimensional system should be identified. The proposed approach is very different from that embodied in building codes. Inelastic structures are classified as either torsionally unrestrained or restrained. It is shown that clearly defined mechanisms that are to be mobilized, enable the acceptable system ductility demand to be estimated. This should ensure that the corresponding demands imposed on critical translatory elements of the system do not exceed their established displacement ductility capacity. To this end familiar quantities, such as element yield displacement and stiffness, are redefined. Comparisons are made of the intents of existing codified design approaches and those emphasising the role of imposed inelastic displacements. A simple treatment of the consequences of earthquake-induced inelastic skew displacements is also addressed. The primary aim of the paper is to offer very simple concepts, based on easily identifiable plastic mechanisms, to be utilized in structural design rather than advancement in analyses. Detailed design applications of these concepts are described elsewhere. The approach is an extension of the deterministic philosophy of capacity design, now used in some countries. © 1998 John Wiley & Sons, Ltd.     

Persisting challenges for performance-based building assessment

Intense research and refinement of the tools used in performance-based seismic engineering have been made, but the maturity and accuracy of these methods have not been adequately confirmed with actual data from the field. The gap between the assumed characteristics of actual building systems and their idealized counterparts used for analysis is wide. When the randomly distributed flaws in buildings as they exist in urban areas and the extreme variability of ground motion patterns combine, the conventional procedures used for pushover or dynamic response history analyses seem to fall short of reconciling the differences between calculated and observed damage. For emergency planning and loss modeling purposes, such discrepancies are factors that must be borne in mind. Two relevant examples are provided herein. These examples demonstrate that consensus-based analytical guidelines also require well-idealized building models that do not lend themselves to reasonably manageable representations from field data. As a corollary, loss modeling techniques, e.g., used for insurance purposes, must undergo further development and improvement.     

基于地震动参数的建筑物震害预测

针对目前我国流行的基于地震烈度的震害预测方法中的不足,本文借助美国广泛使用的地震损失评估软件HAZUS99技术手册中房屋易损性评估方法的表达形式,结合我国的震害经验,提出了一套基于地震动参数的群体建筑物震害预测方法。依据易损性矩阵,采用遗传算法与单纯形法相结合的混合算法反演典型结构的抗力曲线和易损性曲线的参数。给定表示地震作用的需求谱,就可以方便地完成典型结构的震害预测。以两个地区的多层砌体房屋为例,说明了本文提出方法的具体步骤,诊证了可靠性。     

Stability analysis of slope with building loads

In hill areas, landslides are frequent and hazardous. In developing hill areas, many multistoreyed r.c.c. farmed buildings are constructed on hill slope. The building loads are transferred to the hill slope terrain at the foundation level, which may cause hill slope failure. Therefore the stability of hill slope with building loads needs to be checked. In this paper, a procedure has been developed to find the factor of safety against sliding failure of slope considering building loads transferred to the slope. Earthquake forces can also be considered in the analysis. Different types of soils in the slope can be considered. A computer program has been developed based on the formulation presented in the paper and is validated by solving few examples. Stability of slope with differently configured buildings have been studied. Provisions to be made for stepped foundations on hill slopes has been highlighted here.     

多层建筑隔震改造设计

本文介绍了某多层建筑隔震改造的初步设计，采用隔振技术来进行抗震加固改造，上部结构的地震作用可降低，上部结构不需加固即可正常使用；且楼面的加速度反应减小，可以保护内部的仪器设施在地震时不受破坏。该建筑的平面呈L形，其扭转影响较大。考虑到抗风和扭转作用，在边远处选用铅芯叠层橡胶支座。建筑物的隔震改造具有明显的经济效益和社会效益，是今后发展的方向。     

一幢钢筋混凝土建筑结构的强地震反应观测

介绍了美国加州强震观测计划（CSMIP）中一幢建筑结构地震反应台阵的观测方案，描述了被观测结构的有关情况，给出了该台阵于1994年美国北岭地震中获得的结构地震反应的观测资料。     

Simplified seismic analysis of asymmetric building systems

The paper reviews the uncoupled modal response history analysis (UMRHA) and modal pushover analysis (MPA) procedure in the analysis of asymmetric structures. From the pushover curves in ADRS format, showing the relationships of base shear versus roof translation and base torque versus roof rotation, a bifurcating characteristic of the pushover curves of an asymmetric structure is observed. A two‐degree‐of‐freedom (2DOF) modal stick is constructed using lump mass eccentrically placed at the end of beam which is connected with the column by a rotational spring. By converting the equation of motion of a whole structure into 2DOF modal equations, all of the elastic properties in the 2DOF modal sticks can be determined accurately. A mathematical proof is carried out to demonstrate that the 2DOF modal stick is consistent with the single‐degree‐of‐freedom (SDOF) modal stick at elastic state. The bifurcating characteristic of modal pushover curves and the interaction of modal translation and rotation can be considered rationally by this 2DOF modal stick. In order to verify the effectiveness of this proposed 2DOF modal stick, a two‐storey asymmetric building structure was analysed by the UMRHA procedure incorporating this novel 2DOF modal sticks (2DMPA) and conventional SDOF modal sticks (SDMPA), respectively. The analytical results are compared with those obtained by nonlinear response history analysis (RHA). It is illustrated that the accuracy of the rotational response histories obtained by 2DMPA is much better than those obtained by SDMPA. Consequently, the estimations of translational response histories on flexible side (FS) and stiff side (SS) of the building structure are also improved. Copyright © 2006 John Wiley & Sons, Ltd.     

Shear building representations of seismically isolated buildings

Seismic isolation, with its capability of reducing floor accelerations and interstory drifts simultaneously, is recognized as an earthquake resistant design method that protects contents of a building along with the building itself. In research studies, superstructures of seismically isolated buildings are commonly modeled as idealized shear buildings. Shear building representation corresponds to an idealized structure where the beams are infinitely stiff in flexure and axially inextensible; columns are axially inextensible; and rigid floors are supported on these columns. Although it is more convenient to model and analyze a shear building, such an idealization may influence the seismic responses of seismically isolated buildings. This study presents a comparison of the seismic performances of seismically isolated buildings with superstructures modeled as shear buildings to those with full three dimensional superstructures. Both linear and nonlinear base isolation systems with different isolation periods and superstructures with different number of stories are considered.     

Soil-structure interaction effects on an instrumented building

The paper highlights the use of fem and bi-directional lumped-mass-storey-stiffness numerical models for the study of the soil–structure interaction (ssi) effects on an instrumented building. Data on the structural response have been obtained through the project for seismic instrumentation of a 16-storey r/c cast-in-place dwelling building (Chisinau, Republic of Moldova) during a series of earthquakes (Gutenberg–Richter M _GR = 5.0−6.7). The effect of soil–structure interaction is clearly observed comparing the responses recorded on foundation and free-field. ssi becomes more pronounced for higher level of ground shaking amplifying the natural period of the structure and slightly suppressing high frequences on the foundation in comparison with the free-field motion.     

Forced vibration of a tall steel-frame building

The dynamic properties of the twenty-two-story, steel-frame San Diego Gas and Electric Company Building in San Diego, California, have been determined experimentally in a series of co-operative tests between the California Institute of Technology and the University of California at Los Angeles. The building was vibrated by two eccentric mass exciters capable of frequencies up to 10 c/sec and forces as much as 5000 Ib each. The natural frequencies, associated mode shapes and the amounts of damping were determined for the first six modes of vibration in each of the two translational directions, and also in torsion. The mode shapes and frequencies showed, in general, the regularity and uniformity that appears typical of many tall buildings, but the three fundamental modes (nominally NS, EW and torsion) of the structure showed a coupling of translational and rotational components to a degree that was unexpected in a building whose structural frame is essentially symmetric. It is believed that this may be a consequence of the exceptionally small differences among the three fundamental frequencies. The damping in the first eighteen modes of the structure varied from 1.6 to 4.4 per cent, with a slight tendency for the larger values to be associated with the higher modes. Of the simpler damping models that might be used for analysis of the building, constant modal damping appears most appropriate and stiffness or mass proportional damping would not be realistic.     

Earthquake response of a steel frame building

A study has been made of the response, during the San Fernando earthquake 9 February 1971, of the nine-storey steel frame Building 180, located at the California Institute of Technology, Jet Propulsion Laboratory, Pasadena. The analysis throws light on the actual dynamical properties of the building during the earthquake, and also demonstrates that it is possible, when the ground motion is specified, to make accurate predictions of building motions during moderate earthquakes by using a linear viscously damped model. Methods of evaluating the lower mode periods and damping ratios from the earthquake records are described and the values obtained are compared with results from dynamic testing before and after the earthquake and with the periods computed from computer models of the building. Although no structural damage occurred and computed stresses in the steel frame were less than yield stresses, the periods measured by an ambient vibration test after the earthquake were of the order of 10 per cent higher than the pre-earthquake values. The maximum periods during the earthquake were found to be about 30 per cent higher than the post-earthquake periods.     

节能住宅地震反应分析

为研究节能房屋的抗震能力,本文基于墙体试验研究成果,建立了墙体的恢复力模型及其抗震抗剪强度公式,并对内砖外加气混凝土砌块墙体节能房屋进行了地震反应分析.本项研究为节能住宅的推广应用提供了抗震设计依据.