考虑填充墙作用的高层建筑非线性分析

使用SAP2000软件对一栋地下2层,地上12层的商住高层建筑进行弹塑性分析,通过对比考虑填充墙作用及不考虑填充墙作用结构模型的分析结果,分析填充墙作用对结构周期、屋面最大位移、基底力等结构参数的影响,为其它结构的设计与分析提供参考。     

Effects of infill walls on base responses and roof drift of reinforced concrete buildings under time‐history loading

In this study, the effects of infill walls on base reaction and roof drift of reinforced concrete frames were investigated. These effects were studied using 3D finite element method on 216 building models. Number of floors, number of bays, ratio of shear walls and ratio of infilled bays were selected as parameters. Sensitivity analysis was performed to determine the effect of each parameter on base shear, normal base reaction and roof drift. Based on the sensitivity analysis, the percentage of shear walls was the most important parameter affecting base shear, normal base reaction and roof drift. The effect of infill walls on base shear, normal base reaction and roof drift decreased when the percentage of the shear walls increased. The models without any infill walls had minimal normal base reaction under time‐history loading. However, an increase in the percentage of infill walls led to an increase in normal base reaction. The roof drift of the models was not critical. Copyright © 2009 John Wiley & Sons, Ltd.     

Estimation method of tall building structure system in architecture project design

Architecture project design is a key stage to tall building design because its structure form, structure system and main member dimension may be determined, and the possibility to influence construction cost may attain 70–80% in this stage. Based on building conditions in architecture project design, such as building function, storeys, height, length/width ratio, height/width ratio, floor height and the maximum wind pressure, seismic intensity and site type, one of the estimation methods for building structure behaviour under these combined action is presented. In this method, every storey in the building is taken as a macro‐element. The member in the building, such as beams, columns, walls and slabs, are included in the macro‐element. Considering the contribution of each member, the macro‐element stiffness is established for each storey. Then, the estimation analysis of the building structure is carried out following the finite element method. Comparing the analysis results, such as internal force and storey deformation with the usual analysis method, it is known that this estimation analysis method can be used to estimate the behaviour of the building structure system in architecture project design. It is also a useful tool to architects and structure engineers in estimating the applicability of the structure system. Copyright © 2009 John Wiley & Sons, Ltd.     

Seismic fragility assessment of revised MRT buildings considering typical construction changes

The present study investigates the vulnerability assessment of the prototype revised Mandatory Rule of Thumb (MRT) buildings initially designed and detailed for three storeys bare frame building; later modified through variable number of storeys (three, four, and five) and different arrangement of infill walls (bare frame, soft-storey, irregular infilled, and fully infilled). The application of infill walls increases the fundamental frequencies, stiffness, and maximum strength capacity, but reduces the deformation capability than the bare frame building. The vulnerability was also reduced through infill walls, where the probability of exceeding partial-collapse and collapse damage reduced by 80% and 50%, respectively. Furthermore, the increased in storeys (three to five) also increases the failure probability, such that partial-collapse and collapse for fully infilled increases by almost 55% and 80%, respectively. All obtained results and discussions concluded that the structural sections and details assigned for MRT building is not sufficient if considered as bare frame and soft-storey. And increase in number of storeys causes building highly vulnerable although the infill walls were considered.     

On the applicability of pushover analysis for seismic evaluation of medium‐ and high‐rise buildings

The assumption that the dynamic performance of structures is mainly determined from the corresponding single‐degree‐of‐freedom system in pushover analysis is generally valid for low‐rise structures, where the structural behaviour is dominated by the first vibration mode. However, higher modes of medium‐ and high‐rise structures will have significant effect on the dynamic characteristics. In this paper, the applicability of pushover analysis for seismic evaluation of medium‐to‐high‐rise shear‐wall structures is investigated. The displacements and internal forces of shear wall structures with different heights are determined by nonlinear response history analysis, where the shear walls are considered as multi‐degree‐of‐freedom systems and modelled by fibre elements. The results of the analysis are compared with those from the pushover procedure. It is shown that pushover analysis generally underestimates inter‐storey drifts and rotations, in particular those at upper storeys of buildings, and overestimates the peak roof displacement at inelastic deformation stage. It is shown that neglecting higher mode effects in the analysis will significantly underestimate the shear force and overturning moment. It is suggested that pushover analysis may not be suitable for analysing high‐rise shear‐wall or wall‐frame structures. New procedures of seismic evaluation for shear‐wall and wall‐frame structures based on nonlinear response history analysis should be developed. Copyright © 2009 John Wiley & Sons, Ltd.     

Optimum structural modelling for tall buildings

It is a common practice to model multi‐storey tall buildings as frame structures where the loads for structural design are supported by beams and columns. Intrinsically, the structural strength provided by the walls and slabs are neglected. As the building height increases, the effect of lateral loads on multi‐storey structures increases considerably. The consideration of walls and slabs in addition to the frame structure modelling shall theoretically lead to improved lateral stiffness. Thus, a more economic structural design of multi‐storey buildings can be achieved. In this research, modelling and structural analysis of a 61‐storey building have been performed to investigate the effect of considering the walls, slabs and wall openings in addition to frame structure modelling. Sophisticated finite element approach has been adopted to configure the models, and various analyses have been performed. Parameters, such as maximum roof displacement and natural frequencies, are chosen to evaluate the structural performance. It has been observed that the consideration of slabs alone with the frame modelling may have negligible improvement on structural performance. However, when the slabs are combined with walls in addition to frame modelling, significant improvement in structural performance can be achieved. Copyright © 2012 John Wiley & Sons, Ltd.     

Practical modelling of high‐rise dual systems with reinforced concrete slab‐column frames

This paper discusses practical modelling issues pertinent to the design of an irregularly shaped reinforced concrete (RC) high‐rise building currently under development in New York City. The structure analysed consists of a 60‐storey residential tower and a 25‐storey hotel building structurally connected to each other. For the seismic force resistance, a dual system combining ordinary RC shear walls and intermediate slab–column moment frames was used at the upper portion, while a building frame system of ordinary RC shear walls was used at the lower portion of the structure. A variety of models were used to simulate the behaviour of various elements of the structure, with special attention given to overall systemic effects of different member stiffnesses considered to account for distinct stress levels under service and ultimate loads. The models used for slab–column frames and shear walls were verified by comparing with other available models or laboratory tests. The in‐plane flexibility of floor diaphragms at the interface between the two substructures with different geometries was simulated to identify the most critical wind conditions for each structural member. Finally, building dynamic analyses were performed to demonstrate the modelling issues to be considered for the lateral force design of irregular high‐rise buildings. Copyright © 2009 John Wiley & Sons, Ltd.     

One‐dimensional finite element solution for non‐uniform tall building structures and loading

By using a one‐dimensional finite element numerical version based on the continuous medium technique, plane panels of variable geometry and loading are considered, in order to emphasize the capacity of a corresponding very simple computer code. Twin shear walls linked by lintel beams, with walls of lower storeys having bigger cross‐section than the next upper floors, are considered under variable horizontal wind loading through the building height. Afterwards, in that same panel, stronger discrete lintel beam is subsequently placed at each floor position. Results may show where is the optimum level to place those reinforcements in order to get, for example, the smaller top horizontal deflection. The second example considers the case of shear wall curtailment, in the frame shear wall association by pinned bars. Due to the individual behaviour of a single shear wall and of a single frame, it is possible (and real construction may permit that) to construct the wall up to a certain level, smaller than the building height, without having any significant change in the panel top displacement. By using the particular continuous medium finite element computer code, developed by the first author, it is possible to analyse several modelled structures, each having the curtailed wall at subsequent levels, from base to top, and to build an ‘influence line’ to find out the optimum curtailment level. Comparisons with the matrix discrete method and with analytical solutions were considered. Reference to free vibration solutions for such structures was also made. Copyright © 2008 John Wiley & Sons, Ltd.     

Correlation analysis of a reinforced-concrete building under tsunami load pattern and effect of masonry infill walls on tsunami load resistance

The 26 December 2004 Indian Ocean tsunami caused damage to many buildings and killed a lot of people in several Indian Ocean countries, including Thailand. Several reinforced-concrete (RC) buildings in Southern Thailand that were gravity-load-designed buildings suffered damage due to the tsunami. To understand the behaviour of RC buildings under tsunami loads, the one-story building, which was the former office of the Thai Meteorological Department located in Phang-Nga province, was tested under tsunami load patterns. In this research, the RC building is modelled for three-dimensional non-linear static pushover analysis. In the building model, masonry infill walls are idealised as diagonal struts by using uniaxial non-linear springs, and plastic hinges are modelled by non-linear fibre elements. The results of the building model agree well with test results. The effect of masonry infill walls is investigated by considering various wall arrangement patterns. The building with masonry infill walls can resist the lateral load two times higher than the resistance of the building without masonry infill wall. The masonry infill walls with the appropriate arrangement can significantly improve the load-resisting capacity of the building under tsunami loads.     

底部两层框架-抗震墙砖房侧移刚度分析和第三层与第二层侧移刚度比的合理取值

探讨了底部两层框架抗震墙砖房中底部两层层间侧移刚度的简化计算方法,分析指出了计算第二层侧移刚度采用的层间位移应扣除钢筋砼墙在第一层楼板处转角产生的侧移。给出了底部两层框架抗震墙砖房第三层与第二层侧移刚度比的合理取值为１．２～２．０,并且不应小于１．０,供设计人员参考。     

天津现代城办公塔楼抗震设计研究

天津现代城办公塔楼建筑高度339m,采用带加强层的框架-核心筒混合结构体系,为超B级高度超限高层。外框柱为矩形钢管混凝土柱,和伸臂桁架连接的框柱截面适当加大,低区核心筒为型钢混凝土剪力墙。首层层高16.8m,首层核心筒和相邻层采用了钢板混凝土剪力墙,为提高框架刚度首层顶框架梁采用外包钢-混凝土组合梁。首层矩形钢管混凝土柱施工阶段应力较大,对此进行了有限元分析并采用了设置拉杆的措施。介绍了工程的结构体系特点、抗震性能化设计原则和方法、整体计算结果、罕遇地震下弹塑性时程分析结果及地基基础设计。     

Effect of soft‐storey mechanism caused by infill elimination on displacement demand in nonlinear static procedure using coefficient method

In recent earthquakes, many buildings have been damaged due to the soft‐storey mechanism failure. The seismic design codes for buildings do not contain enough criteria to predict the real displacement of such buildings. This paper focuses on evaluating the nonlinear displacement of buildings that fail in soft‐storey mechanism form. Results show that the nonlinear static procedure with coefficient method, which is described in Chapter 3 of ASCE/SEI 41‐06, does not have sufficient accuracy for estimation of structure displacement demand in such buildings. In this paper, the coefficient methodology is used for evaluating the target displacement for 5‐storey, 8‐storey and 15‐storey special moment resisting steel frames. For this purpose, dynamic nonlinear time‐history analysis has been applied for the mentioned structures having a soft‐storey mechanism failure form. The numerical results of storey displacement and interstorey drift were compared with those values obtained from the coefficient method described in Chapter 3 of ASCE/SEI 41‐06. Copyright © 2012 John Wiley & Sons, Ltd.     

An empirical relationship to determine lateral seismic response of mid‐rise building frames under influence of soil–structure interaction

In this study, to determine the elastic and inelastic structural responses of mid‐rise building frames under the influence of soil–structure interaction, three types of mid‐rise moment‐resisting building frames, including 5‐storey, 10‐storey and 15‐storey buildings are selected. In addition, three soil types with the shear wave velocities less than 600 m/s, representing soil classes C_e, D_e and E_e according to AS 1170.4–2007 (Earthquake action in Australia, Australian Standards), having three bedrock depths of 10 m, 20 m and 30 m are adopted. The structural sections are designed after conducting nonlinear time history analysis, on the basis of both elastic method and inelastic procedure considering elastic‐perfectly plastic behaviour of structural elements. The frame sections are modelled and analysed, employing finite difference method adopting FLAC2D software under two different boundary conditions: (a) fixed base (no soil–structure interaction) and (b) considering soil–structure interaction. Fully nonlinear dynamic analyses under the influence of different earthquake records are conducted, and the results in terms of the maximum lateral displacements and base shears for the above mentioned boundary conditions for both elastic and inelastic behaviours of the structural models are obtained, compared and discussed. With the results, a comprehensive empirical relationship is proposed to determine the lateral displacements of the mid‐rise moment‐resisting building frames under earthquake and the influence of soil–structure interaction. Copyright © 2012 John Wiley & Sons, Ltd.     

Seismic response control of base‐isolated buildings using multiple tuned mass dampers

Seismic response of a base‐isolated building equipped with single tuned mass damper (STMD), multiple tuned mass dampers (MTMDs), and distributed multiple tuned mass dampers (d‐MTMDs) under real earthquake ground motions is investigated. Numerical study is carried out using analytical models of five‐, 10‐, and 15‐storey base‐isolated buildings equipped with the STMD, MTMDs, and d‐MTMDs. The buildings are modeled as shear‐type structure with a lateral degree of freedom at each floor level, and the buildings are isolated using the laminated rubber bearing, lead‐core rubber bearing, friction pendulum system, and resilient‐friction base isolator. The coupled differential equation of motion for the buildings are derived and solved in the incremental form using Newmark's step‐by‐step method of integration. From the numerical study conducted, it is concluded that installing a tuned mass damper at each floor level of a base‐isolated building reduces the structural response in terms of top floor acceleration and bearing displacement. It is found that installing the MTMDs and d‐MTMDs are significantly beneficial in reducing top floor acceleration as compared with the STMD. Further, almost comparable reduction in the bearing displacement could be obtained by installing the STMD, MTMDs at top, and d‐MTMDs in the base‐isolated buildings. The d‐MTMDs are more beneficial as compared with the STMD and MTMDs as otherwise huge controller mass can now be divided and distributed on different floor levels.     

Seismic analysis of asymmetric multistorey buildings including foundation interaction and P-Δ effects

This paper presents a method of seismic analysis of three-dimensional asymmetric multistorey buildings founded on flexible foundations. The building-foundation system considered in this study is a linear elastic N-storey asymmetric building with a rigid footing resting on the surface of a linear elastic soil half-space. The method of analysis also includes the P-Δ effects, in which the additional overturning moment and torsional moment at each storey due to P-Δ effects have been replaced by fictitious lateral forces and torques. The whole system has 3N + 5 displacement degrees-of-freedom. The necessary governing equations have been developed considering the three motions of each floor and the five motions of the whole building. Recognizing that the superstructure alone admits classical normal modes, the governing equations of the floors are first uncoupled in terms of footing displacements using the mode superposition method. Substitution of structural deformations, in combination with the dynamic soil-structure interaction force-displacement relationships into the governing equations of the whole system results in five integro-differential equations for footing displacements, which are then solved by numerical step-by-step time history analysis. The floor displacement responses, storey shears, storey torque, etc., are obtained by back substitution of footing accelerations into the relevant governing equations. As a demonstration of the method of analysis and in order to obtain the soil-structure interaction effects, P-Δ effects, and the eccentricity effects, a 10-storey asymmetric building on soft soil was subjected to El Centro 1940 earthquake excitations. The results show that the soft soil conditions increase the lateral deflections, but reduce the twists, storey shears and torques. Increasing eccentricity increases the floor twists and storey torques, however, it does not modify the lateral deflections at the centre of mass, and the total storey shears. The significance of P-Δ effects along with soil-structure interactions on the response of this building has also been discussed.     

采用外套巨型框架大幅度加层设计

阳泉市信托投资公司红楼加层工程 ,将四层框架加至十三层。就设计中结构体系的选择、转换层结构方案的确定、预应力筋布置及张拉方式、转换层大梁施工等内容作了较详细的介绍。为大跨度大幅度加层提供了一个范例 ,可供从事类似工程设计及施工的人员参考。     

武汉世界贸易大厦结构设计

武汉世界贸易大厦地上 58层 ,地下 2层 ,采用C60高强混凝土。基于弹性地基假定 ,用有限元法分析了桩筏基础。利用内外筒支座条件和截面高度随内力变化的方法设计预应力折线板楼盖。在五十四层平面内收 ,选用人字形斜柱转换承托顶部 5层荷载。三道防线后浇带设计 ,保证后浇带防水质量并充分发挥应有的结构作用。主塔空间钢架设计和弹塑性地震反应分析保证建筑风格的实现 ,并满足抗震设防要求 ,使结构设计达到安全可靠、技术先进、经济合理的要求。     

3层砖混办公楼增至7层的作法与分析

某砖混结构办公楼拟由3层改为7层，由于原建筑物上部结构整体刚度较差，故采用外套框架结构方案，使增层部分与原有建筑物完全脱开，施工时拆除原三层顶板，由外套框架的梁、板代替，并对原建筑物的裂缝进行了处理，并采取了抗震加固措施。     

Performance of variable curvature sliding isolators in base‐isolated benchmark building

The performances of variable curvature sliding isolators like variable frequency pendulum isolator (VFPI) and variable curvature friction pendulum system (VCFPS) installed in the base‐isolated benchmark building subjected to bi‐directionally acting seven strong earthquakes have been studied. The shear type base‐isolated benchmark building is modelled as three‐dimensional linear elastic structure having three degrees‐of‐freedom at each floor level. Time domain dynamic analysis of the building has been carried out with the help of constant average acceleration Newmark‐Beta method and non‐linear isolation forces has been taken care by fourth‐order Runge‐Kutta method. The force‐displacement responses of the VFPI and VCFPS are studied under parametric variations of their key characteristics for the comparative performance evaluation. The time history variations of response characteristics and peak response evaluation criteria are also investigated for overall comparison of their performances. The performance of VFPI and VCFPS are observed both in uniform and hybrid isolation systems. The force‐displacement responses of both VFPI and VCFPS subjected to strong near‐field earthquakes show excessively large isolator displacements at higher initial radii of curvature of sliding surface. The large isolator displacements of VFPI and VCFPS can be restrained efficiently by addition of viscous fluid dampers in comparison to the increase in coefficient of friction of isolators. Copyright © 2010 John Wiley & Sons, Ltd.     

Towards optimal design of high‐rise building tube systems

The primary objectives of this study are to investigate effects of varying design parameters on the tube action and shear lag behaviour of a typical reinforced concrete frame‐wall tube building, and propose optimal design approaches for similar tube structures. A parametric study was conducted with selected key design variables on the performance of a 55‐storey hotel building planned in New York City. The lateral force resistance of the case study building is primarily exerted by exterior shear walls in one direction and by exterior moment frames in the other direction, enhanced by the tube action credited to the connection of the walls and the frames. The design variables considered for the parametric study include the column depth, beam depth, column width and beam width of the moment frames. The performance of each model was assessed in terms of overall and critical (maximum) storey drifts, force distributions between various lateral force‐resisting members and shear lag behaviour. Overall, the effects of the column depth (column dimension parallel to the frame direction) on the tube action and shear lag behaviour were more prominent than the other member dimensions. Copyright © 2010 John Wiley & Sons, Ltd.