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.     

消能支撑加固底部框架砌体房屋的弹塑性地震反应分析

本文采用弹塑性时程分析方法,对底部框架多层砌体房屋在不同烈度罕遇地震作用下进行了抗震性能评估;研究了在底部框架内增设消能外包混凝土无粘结钢支撑对房屋抗震性能的影响;对增设消能支撑加固方案和增设抗震墙加固方案进行了对比分析。分析结果表明,在底层框架砌体房屋的底层增设消能支撑可显著降低底层框架的最大层间位移,控制结构的塑性损伤,提高结构的抗震性能。增设消能支撑加固方案与增设抗震墙加固方案相比,结构加固更合理、更易实施。     

砖砌体建筑体外预应力抗震加固技术研究

针对城镇既有砖砌体建筑抗震性能较差的问题,提出了一种适合多层砖砌体房屋的抗震加固新技术,即采用竖向无粘结预应力筋对砌体墙体进行加固,从而改善墙体的抗震性能,提高房屋的整体抗震能力。为了解该技术的加固效果,完成了两批共17片墙体构件的拟静力试验研究和一栋2层足尺房屋模型的拟动力试验研究。墙体构件的试验研究结果表明,该项加固技术可以大幅度提高砖砌体墙体的抗裂能力、受剪承载力和延性。房屋模型的拟动力试验研究则进一步表明,采用该项技术加固后,抗震设防烈度不足8度的房屋,在模拟9度罕遇地震的拟动力作用下基本保持弹性,抗震能力显著提高。在试验研究的基础上,提出了预应力加固砌体墙体的受剪承载力的计算方法。该技术在北京市怀柔区某多层办公建筑的实际应用情况表明,其具有施工工艺简单、工期短、成本低等优势     

Behavior of fully grouted reinforced concrete masonry shear walls failing in flexure: Analysis

This paper contains analysis details of an experimental study conducted to evaluate the ductility and energy dissipation characteristics of reinforced concrete masonry shear walls failing in flexure. The test program consisted of six reinforced concrete masonry shear walls tested under reversed cyclic lateral displacements simulating seismic loading effects. This paper focuses on documenting the levels of ductility attained by the walls and evaluating the contribution of flexure and shear deformations to the overall wall lateral displacement. Analysis of the measured displacements showed that the contribution of shear displacement to the overall wall displacement was significant (up to 28% of total displacement at maximum load) but was not the same for all the walls having height-to-length ratio of 2.0. Displacement ductility values up to 4.5 and 11.4 were measured corresponding to maximum load and 20% strength degradation, respectively. Values up to 3.5 were calculated for the ductility-related seismic response modification factor for the test walls corresponding to design drift levels of 1%. The relationship between the energy dissipation and the ratio of the post-yield to the yield displacement was found to be almost linear for the test walls. In addition, the wall stiffnesses degrade rapidly to about 50% of their initial stiffness at very low drift levels (0.1% drift); however, the test walls maintained at least 80% of their maximum strength up to large displacements (2.2% drift).     

底部两层框架-抗震墙砖房抗震能力的分析方法与设计控制

提出了底部两层框架 -抗震墙砖房框剪层和砖混层的极限受剪承载力、侧移刚度、极限剪力系数计算公式 ,并基于设置不同数量抗震墙的底部两层框架 -抗震墙砖房的实例计算和弹塑性时程分析 ,给出了结构砖混过渡层与相邻框剪层的极限剪力系数比和侧移刚度比的合理取值及薄弱楼层位置判别和破坏状态评定的方法和原则。     

既有多层砌体住宅增设电梯与抗震加固综合改造技术振动台试验研究

我国现有大量建于20世纪七、八十年代的老旧砌体结构住宅,这类住宅材料强度较低,抗震性能较差,大都有抗震加固、增设电梯等结构安全性与建筑功能提升的需求。为避免两项需求单独实施引起的资源浪费,减少入室施工等对房屋正常使用与周边环境的影响,提出了既有多层砌体住宅增设电梯与抗震加固综合改造技术,并制作了一组多层砌体结构缩尺(1∶4)模型,即模型A(未加固的五层无筋砌体结构模型)和模型B(增设电梯、抗震加固综合改造模型),进行了振动台模型对比试验验证。试验结果表明：砌体住宅采用综合改造技术加固后,刚度、基底剪力均有较大幅度提高,结构整体抗震能力明显提高,其脆性破坏的特征亦有显著改善;此外,由于增设的电梯井剪力墙显著增强了结构横向的抗震能力,使得房屋纵、横两个方向的抗震性能趋于均衡,有效地改善了多层砌体结构住宅存在明显抗震强、弱向的自身缺陷。     

碳纤维布抗震加固开门窗洞口砌体墙片的试验研究与受剪承载力分析

通过对6片开门窗洞口砖砌体墙片在低周往复荷载作用下的抗震性能试验研究,探讨碳纤维布用于抗震加固无筋开洞口墙片的破坏形态、受力特性和加固效果,对比不同碳纤维布粘贴方式对无筋开洞口砌体墙片抗震加固效果的影响,据此建议对地震区开窗洞墙体采用沿洞口周围粘贴碳纤维布并在窗洞角部附加锚固碳纤维布条的有效加固方式,对开门洞墙体采用沿洞口周围粘贴碳纤维布并在宽墙肢上对角粘贴碳纤维布的有效加固方式。同时根据试验研究结果,建立以碳纤维布拉杆机制为基础的碳纤维布加固开洞口砌体墙片的受剪承载力计算模型,计算结果与试验结果吻合较好,说明该计算模型能较好地反映碳纤维布与无筋砌体墙体共同工作的受力机理,可供工程设计参考使用。     

砌体房屋墙体加固方法研究与应用

文章介绍了砌体房屋墙体的加固方法,并着重介绍了被现行抗震加固规程明确认可的可视为改变了原有砌体结构体系的加固方法—钢筋混凝土板墙加固(简称"夹板墙")。但是夹板墙加固方法也存在着传统加固方法的缺陷,因此,探索出一种可以改变砌体结构体系的,安全、先进、合理的新加固方法是很有必要的。由此,提出了格构式钢板组合剪力墙加固砌体房屋的方法。     

砌块房屋抗震性能及其加固的研究

本文在砌块房屋抗震性能方面,主要研究了单片墙的垂直压应力,开洞和高宽比等三种效应以及探讨了砌块墙在水平力作用下的破坏机理、滞回特性和强度计算。共进行了29片墙体和1栋1:2两层模型房屋的试验。 在用钢筋混凝土柱加固砌块砌体的抗震能力的研究方面,重点放在加固前与加固后,破坏与修复等基本性能的对比,以及加固后的破坏机理和其强度计算。共进行了4片开洞墙和2栋1:2两层模型房屋的试验。 此外,本文也给出了在水平力作用下砌块砌体的极限剪切变形值。     

Masonry wall frame design and performance

Tall masonry building in active seismic or severe wind regions have typically been designed as shear wall buildings. This paper presents an alternative lateral force resisting system cailed a wall frame. This new masonry system is particularly advantageous for seismic and windy regions because it utilizes the nonlinear inelastic load deformation characteristics of the masonry beams and is thus a ductile system. Basic design assumptions and experimental test data are presented.     

静压桩的静压力施加技术研究与应用

对承重墙下条形基础加固工程中的静压桩技术进行了讨论,通过工程实例指出了在砌体危房加固工程中,当由于软弱地基上墙下条形基础沉降过大时,可优先采用本文改进的静压桩静压力技术加固承重墙下基础.     

Lateral performance and load carrying capacity of an unreinforced, CFRP-retrofitted historical masonry vault - A case study

Historical masonry buildings, composed of adobe/brick building blocks that are connected together with clay, lime-clay, or gypsum-clay mortars are vulnerable to earthquake. Many of these historical buildings are world heritage listed. They are highly valued and it is important that they are evaluated for their capacity to resist earthquakes, or strengthened if found not to be adequate. In this paper, the structural behavior and lateral resistance of a heritage brick vault with adobe piers built in 1935, Yazd, Iran is investigated under lateral loads. A nonlinear finite element analysis is used based on the concepts of homogenized material and smeared model in which the masonry is modelled as an anisotropic continuum. For this macro-modelling, the mechanical properties of continuum masonry are determined by experimental tests. Based on the literature review performed in this paper, no similar tests on structures of this kind have been identified elsewhere. Finally, the vault and the piers were retrofitted using Carbon Fiber Reinforced Polymer (CFRP) laminates at extrados in order to compare their failure mechanisms and lateral strength before and after retrofitting.     

A simplified method for determining sway in reinforced concrete dual buildings and design applications

Sway analyses of reinforced concrete buildings generally are carried out with computer programs. However, as the number of iterative solutions increase, the process may become tedious. This paper proposes a simple analytical method to evaluate sway of dual buildings subject to various types of lateral loads. The proposed method is based on the continuum model. Story drift limited by building codes can be controlled by the proposed method. Likewise, design engineers can use the simple analytical expressions to calculate the stability index, which includes sway terms at each story level. Stability index equation without sway terms is obtained by using the developed analytical expressions. Use of the equation, which is free of sway terms, is quite simple. Additionally, by using the proposed method, shear wall–frame interaction can be modeled simply. Thus, moment at the base of shear walls can be determined by using this model. Copyright © 2012 John Wiley & Sons, Ltd.     

Coupled shear‐flexural model for dynamic analysis of fixed‐base tall buildings with tuned mass dampers

An equivalent discrete model is developed for time domain dynamic analysis of uniform high‐rise shear wall‐frame buildings with fixed base and carrying any number of tuned mass dampers (TMDs). The equivalent model consists of a flexural cantilever beam and a shear cantilever beam connected in parallel by a finite number of axially rigid members that allow the consideration of intermediate modes of lateral deformation. The proposed model was validated by a building whose lateral resisting system consists of a combination of shear walls and braced frames. The results showed the effectiveness of TMDs to reduce the peak displacements, interstory drift ratio, and accelerations when the building is subjected to a seismic load. The root mean square accelerations due to along‐wind loads also decrease if TMDs are attached to the building.     

Repair of in-plane shear damaged masonry walls with external FRP

Extensive damage in a large number of existing masonry buildings during recent earthquakes has shown the need for structural repairing techniques for masonry structures. Externally bonded fibers (FRP) is a retrofitting technique that has been shown that can be used to repair or strengthen reinforced concrete and masonry structures. Masonry walls strengthened with FRP can have large increase in strength, but the effect of the of the presence of damage in the walls at the time of the repair has not been studied. Four full-scale shear-dominant clay brick masonry walls, initially damaged in shear by loading them up to their maximum strength, were repaired using two configurations of externally bonded carbon fiber strips and tested under cyclic shear loading up to failure. It was observed that the maximum strength and deformation capacity, as well as the cracking pattern and failure mode, of the repaired walls was similar to that of undamaged walls that were strengthened with the same reinforcing schemes.     

GFRP加固砖墙抗震抗剪承载力的设计公式

基于1片未加固带壁柱墙体和8片玻璃纤维复合材料加固带壁柱墙体抗震试验的试验结果和纤维复合材料的桁架受力模型,并借鉴现行抗震规范中未加固墙体的抗震抗剪设计计算公式,提出了FRP加固带壁柱砖墙抗震抗剪承载力的设计计算公式,试验结果与所得公式计算结果比值的平均值为2.23,样本方差为0.033,可供进一步研究和工程设计参考使用。     

Design and behaviour of a reinforced concrete high‐rise tube building with belt walls

This paper discusses modelling, analysis and design issues for a 55‐storey hotel building recently planned for New York City, USA. The lateral force resistance of the investigated building primarily makes use of exterior reinforced concrete shear walls in one direction and exterior reinforced concrete moment frames in the other direction, in which tube action credited to the connection of the walls and frames was designed to play a significant role in the lateral stiffness and strength. In addition, a full‐storey belt wall system, enclosing the entire perimeter of the building at approximately the mid‐height, is expected to provide a considerable contribution to the lateral force resistance. In this paper, the contribution of tube action and the belt wall system to structural behaviour is investigated in terms of quantitative measures such as lateral drift, building dynamic properties and flange frame contribution to overturning moment resistance. In addition, axial force distribution among the various vertical members under lateral forces is discussed for each of the two principal building directions. Finally, the seismic behaviour of the investigated building is qualitatively discussed in order to propose a seismic force‐resisting system classification into which this concrete tube system would fit. Copyright © 2010 John Wiley & Sons, Ltd.     

带现浇混凝土填充墙的剪力墙抗震性能试验研究

为研究现浇混凝土填充外墙对剪力墙结构抗震性能的影响,完成了10个采用不同做法和不同形式填充墙的足尺墙体试件和2个无填充墙对比试件的拟静力试验。结果表明：填充墙与主体结构之间采用聚苯板条分隔做法和PVC板条分隔做法时,填充墙对主体结构的影响基本一致,均一定程度上改变了主体结构破坏过程及最终破坏形态,对于PVC板条分隔做法的试件,其破坏时的延性好于聚苯板条分隔做法的试件;填充墙增大了试件的承载能力,对于聚苯板条分隔做法的试件,其峰值荷载为无填充墙试件的1.37~3.31倍,两种做法填充墙试件的峰值荷载大小相当;填充墙减小了试件的变形能力,对于极限位移角,聚苯板条分隔做法的试件为无填充墙试件的20%~65%,PVC板条分隔做法的试件的变形能力明显大于聚苯板条分隔做法的试件;除聚苯板条分隔做法的结构洞墙试件外,其余试件的极限位移角均满足剪力墙结构抗震变形能力要求;填充墙显著增大了试件弹性及弹塑性阶段的刚度。基于试验结果,建议结构计算时合理考虑填充墙的不利影响,工程中尽量避免采用结构洞填充墙,对填充墙部位的结构构件及填充墙采取一定的加强措施。     

Experimental study on seismic behavior of shear wall with cast-in-situ concrete infilled walls

为研究现浇混凝土填充外墙对剪力墙结构抗震性能的影响，完成了10个采用不同做法和不同形式填充墙的足尺墙体试件和2个无填充墙对比试件的拟静力试验。结果表明：填充墙与主体结构之间采用聚苯板条分隔做法和PVC板条分隔做法时，填充墙对主体结构的影响基本一致，均一定程度上改变了主体结构破坏过程及最终破坏形态，对于PVC板条分隔做法的试件，其破坏时的延性好于聚苯板条分隔做法的试件；填充墙增大了试件的承载能力，对于聚苯板条分隔做法的试件，其峰值荷载为无填充墙试件的1.37~3.31倍，两种做法填充墙试件的峰值荷载大小相当；填充墙减小了试件的变形能力，对于极限位移角，聚苯板条分隔做法的试件为无填充墙试件的20%~65%，PVC板条分隔做法的试件的变形能力明显大于聚苯板条分隔做法的试件；除聚苯板条分隔做法的结构洞墙试件外，其余试件的极限位移角均满足剪力墙结构抗震变形能力要求；填充墙显著增大了试件弹性及弹塑性阶段的刚度。基于试验结果，建议结构计算时合理考虑填充墙的不利影响，工程中尽量避免采用结构洞填充墙，对填充墙部位的结构构件及填充墙采取一定的加强措施。     

Seismic evaluation of a 56‐storey residential reinforced concrete high‐rise building based on nonlinear dynamic time‐history analyses

In recent decades, shear walls and tube structures have been the most appropriate structural forms for the construction of high‐rise concrete buildings. Thus, recent Reinforced Concrete (RC) tall buildings have more complicated structural behaviour than before. Therefore, studying the structural systems and associated behaviour of these types of structures is very important. The main objective of this paper is to study the linear and nonlinear behaviour of one of the tallest RC buildings, a 56‐storey structure, located in a high seismic zone in Iran. In this tower, shear wall systems with irregular openings are utilized under both gravity and lateral loads and may result in some especial issues in the behaviour of structural elements such as shear walls and coupling beams. The analytical methodologies and the results obtained in the evaluation of life‐safety and collapse prevention of the building are also discussed. The weak zones of the structure based on the results are introduced, and a detailed discussion of some important structural aspects of the high‐rise shear wall system with consideration of the concrete time dependency and constructional sequence effects is also included. Copyright © 2010 John Wiley & Sons, Ltd.