Strengthening of Gravity Load Designed Reinforced Concrete Frames with the External RC Shear Walls

2013 ◽  
Vol 747 ◽  
pp. 265-268 ◽  
Author(s):  
Fatih Bahadir ◽  
Mehmet Kamanli ◽  
Hasan Husnu Korkmaz ◽  
Fatih Suleyman Balik ◽  
Alptug Unal ◽  
...  

Turkey is situated on a very earthquake zone of the world namely Alp-Himalayan Earthquake Zone. Several destructive earthquakes resulted in high dead losses in the last century. Turkish building stock consisted of nonductile RC framed structures commonly 3 to 7 stories. The common properties of the existing structures is the poor lateral resistance. The residental buildings with poor earthquake resistance must be rehabilitated with a rapid, economical, feasible and effective strengthening methods. The external shear wall addition to the existing poor frame is studied experimentally in this study. 6 specimens were tested under reversed cyclic lateral loading simulating the seismic action. The first specimen was the reference specimen and didn't contain any strengthening and tested to see reference behaviour. The other specimens were strengthened with external shear walls with or without openings. The size of the openings is a parameter in the study. Secons specimen didn't contain any opening. Columns of the frames also jacketed with reinforced concrete. The maximum lateral load carrying capacity, ductility capacities, energy consuption capacities, improvement in the lateral rigidities were investigated.

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.


Reinforced concrete (RC) framed structures are widely used as load transferring system in residential and commercial buildings. Even though the RC frames are designed for gravitational and seismic forces, but they are week under severe seismic events. The main disadvantage of the framed structures is inefficient bracing systems designed in it. This investigation is conducted mainly to study the effective bracing system in the RC framed structure to transfer the seismic force. This research aims to study the seismic performance of RC frames influenced by the various types of cross bracings under cyclic loading. The finite element analysis software package ABAQUS is used to investigate the braced RC frames analytically. The research scheme consists of three RC frames; the bare frame, the bare frame with single X-bracing (X frame), double X bracing (D-X frame) along the height. The structural parameters include, load-displacement hysteresis envelope, stiffness degradation and energy absorption were studied to analyze the performance of bracings. The results showed that the X frame and D-X frame noticeably increased the lateral strength, stiffness and energy dissipation properties compared to the bare RC frame. The results also indicated that the addition of X bracing along the height significantly enhanced the structural parameters of the RC frame.


Author(s):  
T. Paulay

The likely effects of secondary moments due to the gravity load, which is being laterally displaced during inelastic seismic storey drift, upon ductile reinforced concrete frames is examined. Existing building code recommendations and design procedures relevant to the phenomenon are briefly reviewed. The probable effect of P-delta moments on inelastic dynamic
frame response is discussed. With the aid of illustrations various design considerations are presented. It is suggested that if strength demand
due to P-delta effects exceeds 15% of the ideal lateral load carrying capacity of a subframe, this strength demand should be met. From the comparison of the elastic and inelastic deformations of a frame due to earthquake loading, recommendations are made for the estimation of critical inelastic drifts in the lower half of the frame. This is subsequently used to quantify the problem with the aid of the "stability index". The quantitative evaluation of P-delta effects for an 18 storey frame is illustrated in the appendix.


2013 ◽  
Vol 405-408 ◽  
pp. 2020-2024
Author(s):  
Li Ming Wu

Taking the typical reinforced concrete stiffening truss suspension bridge as example, finite element analysis model under seismic action is established. Dynamic response analysis is done on this suspension bridge using finite element software ANSYS and contrast is done between this analysis result and structural response under gravity load effect. Contrast result shows that structural response under seismic action is obviously higher than that under gravity load effect in which internal force response is greater than displacement. The function of dynamic load should be taken into account in the design of bridge structure in order to provide reference for the structural design of long-span flexible bridge.


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