阻尼填充墙优化布置对不规则框架结构抗震性能的影响          下载免费PDF全文

刘洁  郭鑫龙 《地震工程学报》2017,39(3):411-416

在不规则结构中,填充墙的表现对框架结构的局部以及整体抗震性能的表现显得非常重要。随着阻尼填充墙的深入研究,大大提高了框架填充墙结构的抗震性能。但由于阻尼填充墙施工工艺复杂、施工成本较高,很难得以大规模使用。为了实现既降低施工的难度和成本又提高框架结构的抗震性能,本文选取一座不规则框架结构对其地震表现进行分析。采用局部优化布置阻尼填充墙的方法,达到既提高结构抗震性能又降低施工难度和成本的要求,为框架填充墙结构的设计提供一定的建议。  相似文献   

楼层侧向刚度比对砌体结构地震易损性的影响分析     

赵文哲  温增平  徐超  陈波 《震灾防御技术》2018,13(4):878-892

砌体结构的震害现象表明楼层侧向刚度不均匀分布是造成其破坏的重要原因之一。本文开展楼层侧向刚度变化对结构易损性的影响分析。以3层和6层砌体结构为例,采用等效多自由度层间剪切模型,基于非线性动力时程分析,定量研究了竖向刚度不规则性对砌体结构易损性的影响。以结构最大层间位移角为地震反应参数,借助增量动力分析及回归拟合方法,建立了基于峰值加速度的结构易损性曲线。通过改变楼层的侧向刚度值来模拟薄弱层,研究了楼层刚度变化对结构不同破坏状态超越概率的影响。通过改变底层与二层的侧向刚度比,分析了底部刚度突变对结构不同破坏状态超越概率分布的影响。研究表明:与规则结构相比,当刚度突变位于结构底层时,在地震作用下结构易损性相对较高;随着底层与二层的侧向刚度比从0.5增大至1.2,结构易损性逐渐降低。当刚度比为1.5时,结构薄弱层由底层转移至二层,结构整体易损性增加;当底层与二层侧向刚度比小于1时,结构倒塌易损性要显著高于规则结构。  相似文献   

Fragility functions for masonry infill walls with in‐plane loading          下载免费PDF全文

Andrea Chiozzi  Eduardo Miranda 《地震工程与结构动力学》2017,46(15):2831-2850

Recent seismic events have provided evidence that damage to masonry infills can lead not only to large economic losses but also to significant injuries and even fatalities. The estimation of damage of such elements and the corresponding consequences within the performance‐based earthquake engineering framework requires the construction of reliable fragility functions. In this paper, drift‐based fragility functions are developed for in‐plane loaded masonry infills, derived from a comprehensive experimental data set gathered from current literature, comprising 152 masonry infills with different geometries and built with different types of masonry blocks, when tested under lateral cyclic loading. Three damage states associated with the structural performance and reparability of masonry infill walls are defined. The effect of mortar compression strength, masonry prism compression strength, and presence of openings is evaluated and incorporated for damage states where their influence is found to be statistically significant. Uncertainty due to specimen‐to‐specimen variability and sample size is quantified and included in the proposed fragility functions. It is concluded that prism strength and mortar strength are better indicators of the fragility of masonry infills than the type of bricks/blocks used, whose influence, in general, is not statistically significant for all damage states. Finally, the presence of openings is also shown to have statistically relevant impact on the level of interstory drift ratio triggering the lower damage states.  相似文献   

Seismic Damage to Owner-Built RC Frames in Charikot during the 2015 Nepal Earthquake Sequence     

Qu Zhe  Wang Tao  Lin Xuchuan  Zhang Haoyu  Yang Yongqiang 《中国地震研究》2018,32(4):584-601

The damage to the masonry-infilled reinforced concrete (RC) frame buildings in Charikot, the capital city of Dolakha district in Nepal, during the 2015 April-to-May Nepal earthquake sequence is reported. Most of these buildings were built by the owners with little governmental inspections regarding their structural design or constructional quality. Although they generally performed better than other structural systems such as stone-masonry houses, the RC frames sustained extensive damage ranging from cracking of infill to complete collapse. In particular, eight of the 72 inspected RC frames alongside an uphill street collapsed in different ways. In addition to the un-engineered nature of these RC frames, their collapse could also be attributed to multiple technical reasons including the effect of terrain, the pounding between adjacent buildings and the accumulative damage in the earthquake sequence.  相似文献   

Empirical‐based out‐of‐plane URM infill wall model accounting for the interaction with in‐plane demand          下载免费PDF全文

《地震工程与结构动力学》2018,47(3):802-827

The role of masonry infills in the seismic behavior of reinforced concrete buildings has been widely studied in terms of their strength and stiffness contribution in the in‐plane (IP) direction, while fewer studies have been carried out on their response and modeling in the out‐of‐plane (OOP) direction. In this paper, the state of the art in code and literature provisions regarding infills' OOP capacity and seismic demand is presented, together with a review of the experimental tests that have been carried out to investigate infills' OOP behavior and the effects of IP‐OOP interaction. This review aims to collect an experimental database that is used to evaluate the effectiveness of literature and code provisions and to propose a semiempirical approach both for predicting infills' OOP strength, stiffness, and displacement capacity and for modeling the effects of IP displacement demand on OOP behavior and vice versa. Then, the state of the art on modeling of infills' OOP behavior and IP‐OOP interaction is presented together with a new macro model based on the proposed formulations and conceived to represent the IP and OOP behavior by taking into account the mutual interaction effects. Finally, the proposed model is used for an example application on two case‐study buildings, showing the effects of taking into account or neglecting the IP‐OOP interaction phenomena.  相似文献   

Effect of infill materials on the performance of geocell reinforced soft clay beds     

Amarnath M. Hegde  T.G. Sitharam 《Geomechanics and Geoengineering》2015,10(3):163-173

The present study deals with model plate load tests conducted on geocell reinforced soft clay beds to evaluate the effect of infill materials on the performance of the geocell. Commercially available Neoweb geocells are used in the study. Three different infill materials namely aggregate, sand and local red soil were used in the study. The load carrying capacity of the geocell reinforced bed (as compared to an unreinforced bed) was found to be increased by 13 times for the aggregate infill, 11 times for the sand infill and 10 times for the red soil infill. Similarly the reduction in the settlement was in the order of 78%, 73% and 70% aggregate, sand and the red soil infill materials respectively. Results suggest that the performance of the geocell was not heavily influenced by the infill materials. Further, numerical simulations were carried out using FLAC^2D to validate the experimental findings. The results from numerical studies are in reasonably good agreement with the experimental findings. The outcome of this work is successfully implemented in the construction of the geocell foundation to support a 3 m high embankment in the settled red mud in Lanjighar (Orissa) in India.  相似文献   

Cyclic testing of a single bay reinforced concrete frames with various types of masonry infill     

Jurko Zovkic  Vladimir Sigmund  Ivica Guljas 《地震工程与结构动力学》2013,42(8):1131-1149

In this paper, a contribution of various types of masonry infill to the behaviour of reinforced concrete frames under lateral loads is presented. As a part of the bigger project, ten one‐bay, one‐storey reinforced concrete frames were designed according to the EC8, built in a scale 1:2.5, infilled with masonry and tested under constant vertical and cyclic lateral load. The masonry wall had various strength properties, namely, high strength hollow clay brick blocks, medium strength hollow clay brick blocks and low strength lightweight autoclaved aerated concrete blocks. There were no additional shear connectors between the masonry and frame. The results showed that the composite ‘framed wall’ structure had much higher stiffness, damping and initial strength than the bare frame structure. Masonry infill filled in the load capacity gap from very low (0.05%) to drifts when the frame took over (0.75%). The structures behaved as linear monolithic elements to drifts of 0.1%, reached the maximum lateral capacities at drift of 0.3%, maintained it to drifts of 0.75% and after that their behaviour depended on the frame. Masonry infill had severe damage at drift levels of about 0.75% but contributed to the overall system resistance to drifts of about 1%. At that drift level, the frame had only minor damage and was tested to drifts of about 2% without any loss of capacity. Improvement of the ‘infill provisions’ in the codes could be sought by taking into account the contribution of a common masonry that reduces expected damages by lowering the drift levels. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Failure process of masonry buildings during earthquake and associated casualty risk evaluation   总被引：1，自引：0，他引：1  

Aiko Furukawa  Yutaka Ohta 《Natural Hazards》2009,49(1):25-51

Collapse of masonry structures during an earthquake is analyzed using the three-dimensional distinct element method (3D-DEM) code developed by the first author. The DEM is a numerical analysis technique, in which positions of elements are calculated by solving equations of motion step by step. Both individual and group behavior can be simulated. The structure is modeled as an assembly of distinct elements connected by virtual springs and dashpots, where elements come into contact. First, the validity of the developed 3D-DEM code is confirmed by comparing analytical results with static experimental results of masonry walls. Second, failure process of masonry buildings due to earthquake is investigated using DEM. Effects of reinforcing methods are also examined. Finally, injury to human bodies in the collapsing masonry buildings is also calculated. Assuming that occupants lie down on the floor, two types of casualty criteria are introduced and assessed.  相似文献   

Cyclic response of masonry infilled RC frames: Experimental results and simplified modeling     

《Soil Dynamics and Earthquake Engineering》2014

The recent large interest in nonlinear seismic analysis methods, static and dynamic, has required proper strategies of modeling based on reliable, and at the same time easy to use, constitutive laws for the structural elements. Regarding the behavior of framed structures, special attention has to be devoted to infills because of the key role they play in modifying overall stiffness, strength and ductility under seismic excitation. Pointing out the attention on this topic the paper discusses a criteria for modeling the structural behavior of infills based on a macromodeling approach, that is to say on the substitution of infills with diagonal pin jointed struts. Is here shown how multilinear plastic link elements governed by a hysteretic Pivot model, available in different FEM codes, can be appropriately used to model the equivalent struts to perform linear or nonlinear analyses. In order to enlarge experimental knowledge on cyclic behavior of infilled frames structures and as reference for developing the above mentioned modeling strategy, an experimental campaign on single-storey, single-bay, fully infilled frames with different kinds of masonry and subjected to lateral cyclical loads, was carried out, and some others available in the literature are referred to. Validation of Pivot modeling approach was carried out comparing experimental results and computer simulations of the experimental tests. In the paper hysteresis parameters values calibrating Pivot law are also given for involved masonry infills typologies and some proposals for correlation between strength and stiffness of infilled frames and of masonry infills are provided as a tool for the quick calibration of the Pivot model in practical applications.  相似文献   

The palaeo‐valley infilling glaciogenic Sarah Formation,an example from Rahal Dhab palaeo‐valley,Saudi Arabia     

《Sedimentology》2018,65(3):851-876

The Sarah Formation is a glaciogenic sedimentary unit deposited along the Gondwana margin during the latest Ordovician ice age and represents a major hydrocarbon reservoir in northern Saudi Arabia. Large‐scale glacial palaeo‐valleys cut into the Qasim Formation and were infilled by the Sarah Formation. Post‐glacial transgression in the earliest Silurian resulted in the deposition of the Qusaiba Shale Member and associated organic‐rich basal source rocks, which cap the Sarah Formation infilled palaeo‐valleys. This unique setting makes the Sarah Formation an important emerging exploration target in Saudi Arabia. This study focuses on the facies and depositional architecture in seismic‐scale outcrops of the Sarah Formation in north‐western Saudi Arabia. The Rahal Dhab palaeo‐valley provides a 100 km long dip‐oriented cross‐section which has been covered by 24 vertical sections, sedimentary architectural analyses at metre to kilometre scale and by three cored shallow boreholes. In the Rahal Dhab palaeo‐valley, the Sarah Formation was deposited in a proglacial setting that ranged from marginal marine to offshore prodelta and is made up of three units: (i) the Sarah Sandstone; (ii) the Sarah Shale; and (iii) the Uqlah Member. This study shows the relationships between these three units and architectural controls on reservoir quality in this system. This paper contributes to the regional understanding of the Sarah Formation, and the new depositional model of the Rahal Dhab palaeo‐valley provides an outcrop‐reservoir analogue for hydrocarbon exploration in adjacent areas.  相似文献