Seismic Analysis of Vertically Regular and Irregular Buildings with Shear Walls and RCC X-Bracing System

Author(s):  
Mohd Zahid ◽  
Md Miraz ◽  
Mohd Faizan Saifi Warsi ◽  
Shilpa Pal
2019 ◽  
Vol 3 (Special Issue on First SACEE'19) ◽  
pp. 173-180
Author(s):  
Giorgia Di Gangi ◽  
Giorgio Monti ◽  
Giuseppe Quaranta ◽  
Marco Vailati ◽  
Cristoforo Demartino

The seismic performance of timber light-frame shear walls is investigated in this paper with a focus on energy dissipation and ductility ensured by sheathing-to-framing connections. An original parametric finite element model has been developed in order to perform sensitivity analyses. The model considers the design variables affecting the racking load-carrying capacity of the wall. These variables include aspect ratio (height-to-width ratio), fastener spacing, number of vertical studs and framing elements cross-section size. A failure criterion has been defined based on the observation of both the global behaviour of the wall and local behaviour of fasteners in order to identify the ultimate displacement of the wall. The equivalent viscous damping has been numerically assessed by estimating the damping factor which is in use in the capacity spectrum method. Finally, an in-depth analysis of the results obtained from the sensitivity analyses led to the development of a simplified analytical procedure which is able to predict the capacity curve of a timber light-frame shear wall.


2014 ◽  
Vol 8 (1) ◽  
pp. 104-121 ◽  
Author(s):  
T. O. Tang ◽  
R. K.L. Su

Seismic analyses of concrete structures under maximum-considered earthquakes require the use of reduced stiffness accounting for cracks and degraded materials. Structural walls, different to other flexural dominated components, are sensitive to both shear and flexural stiffness degradations. Adoption of the gross shear stiffness for walls in seismic analysis prevails particularly for the design codes in the US. Yet available experimental results indicate that this could overstate the shear stiffness by more than double, which would hamper the actual predictions of building periods and shear load distributions among columns and walls. In addition, the deformation capacity could be drastically understated if the stipulated constant ductility capacity is adopted. This paper reviews the available simplified shear and flexural models, which stem from classical mechanics, empirical formulations and/or parametric studies, suitable for structural walls at the state-of-the-art. Reviews on the recommended flexural and shear stiffnesses by prominent design codes such as ACI318-11, Eurocode 8 and CSA are included. A database comprised of walls subjected to reverse-cyclic loads is formed to evaluate the performance of each model. It is found that there exist classical models that could outweigh overconservative codified values with comparable simplicity for practical uses.


2019 ◽  
Vol 10 (1) ◽  
pp. 284 ◽  
Author(s):  
Rong Chen ◽  
Canxing Qiu ◽  
Dongxue Hao

Multi-story steel frames are popular building structures. For those with insufficient seismic resistance, their seismic capacity can be improved by installing buckling-restrained braces (BRBs), which is known for high energy dissipation capacity, and the corresponding frame is denoted as BRB frame (BRBF). However, BRBFs are frequently criticized because of excessive residual deformations after earthquakes, which impede the post-event repairing work and immediate occupancy. Meanwhile, self-centering braces (SCBs), which were invented with a particular purpose of eliminating residual deformation for the protected structures, underwent fast development in recent years. However, the damping capability of SCBs is relatively small because their hysteresis is characterized by a flag shape. Therefore, this paper aims to combine these two different braces to form a hybrid bracing system. A total of four combinations are proposed to seek an optimal solution. The multi-story steel frames installed with BRBs, SCBs, and combined braces are numerically investigated through nonlinear static and dynamic analyses. Interested seismic response parameters refer to the maximum story drift ratios, maximum floor accelerations, and residual story drift ratios. The seismic analysis results indicate that the frames using the combined bracing system are able to take the advantages of BRBs and SCBs.


2016 ◽  
Vol 111 (10) ◽  
pp. 1658 ◽  
Author(s):  
Shaikh Abdul Aijaj Abdul Rahman ◽  
Ansari Ubaidurrahman Salik

2016 ◽  
Vol 857 ◽  
pp. 212-218
Author(s):  
Kiran Rangwani ◽  
Svetlana Brzev

Confined Masonry (CM) structural system consists of masonry walls enclosed by reinforced concrete (RC) confining elements (tie-columns and tie-beams) and is usually supported by reinforced concrete floors and roof. This technology has been widely used for construction of low-and medium-rise buildings in Latin America, Europe, South Asia, and Middle East, and it has a proven record of good performance in damaging earthquakes. CM construction is not currently practiced in India and is not addressed by Indian design codes. Seismic analysis of CM wall panels can be performed using Wide Column Model (WCM), also known as Equivalent Frame Model. WCM is a macro model where a wall structure and the supporting floors and roof are idealized as a bare frame. CM walls can be modelled as wide columns with transformed section properties accounting for composite action of masonry and RC tie-columns. Beams in these bare frames have rigid segments simulating the effect of wall stiffness, and flexible segments that simulate the effect of floor and roof slabs. WCM has been recognized as a viable model for seismic analysis of CM buildings in Latin American countries, however this model is not well known in India. The results presented in this paper are based on linear elastic analyses of typical multi-storey CM solid walls and walls with openings. The output parameters include shear forces, bending moments, stiffness, and lateral displacements. A comparison of the results obtained using the WCM and the Finite Element Method (FEM) has been presented. WCM can be useful for seismic analysis of CM buildings since it does not require significant computational effort and can be applied using a variety of software packages.


Shear walls are a structural system which gives solidness or stability to structures from lateral loads like wind, seismic loads. The structural systems are fabricated by reinforced concrete, plywood/timber unreinforced, reinforced masonry at which these systems are subdivided into coupled shear walls, shear wall frames, shear panels and staggered walls. The present paper work was made in the interest of studying and analysis of various research works involved in enhancement of shear walls and their behaviour towards lateral loads. In SAP2000 analysis we found that when we apply lateral force between the stories the amount of compression and tension force between the stories obtained is equal to the manual analysis .In STAAD.PRO, we analyzed the light frame shear wall for seismic analysis. The estimated results for light frame shear wall with one storey, shear wall with two storey and shear wall with three storey shown similar to the results which are obtained by using FEM software like STAAD and SAP2000.


Author(s):  
Mohamed Laissy ◽  
Mohammed Ismaeila

Nowadays, evaluation of the seismic performance of existing buildings has received great attention. This paper was carried out to study the effect of strengthening the existing reinforced concrete (RC) school buildings in Medina, Saudi Arabia through assessing the seismic performance and retrofitting where seismic analysis and design were done using equivalent static analysis method according to Saudi Building Code (SBC 301) and SAP2000 software. A Typical five-story RC school building designed according to the SBC301 has been investigated in a comparative study to determine the suitable strengthening methods such as RC shear walls and steel X-bracing methods. The results revealed that the current design of RC school buildings located in Medina was unsafe, inadequate, and unsatisfied to mitigate seismic loads. Moreover, adding steel X-bracing and RC shear walls represent a suitable strategy to reduce their seismic vulnerability.


Author(s):  
Gajagantarao Sai Kumar ◽  
Purushotham Rao ◽  
Partheepan Ganesan

Multi-storey buildings tend to get damaged mainly during earthquake. Seismic analysis is a tool for the estimation of structural response in the process of designing earthquake resistant structures and/or retrofitting vulnerable existing structures. The principle purpose of this work is to analyze and design a building with a shear wall and also to find the appropriate position of shear wall that result in maximum resistance towards lateral forces and minimum displacement of the structure. In this study, a G+7 multi-storey building of 15 m ×20 m in plan area has been chosen and modelled using ETABS. The developed model was validated by solving manually and the results were validated in ETABS. Thereafter, 4 different new plans were modelled in ETABS located in the same earthquake zone area. These plans have shear wall concepts are implemented on the building at four different locations. Seismic, vibration and response spectrum analysis were performed on these structures. Salient parameters such as storey stiffness, storey displacement and storey drift were computed using the ETABS model. These were compared with that of the frame having no shear walls. By comparing the results obtained at different shear wall locations, the best plan with the shear wall having minimum lateral storey displacement and maximum stiffness is suggested for this location.


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