Seismic Rehabilitation of Beam-Column Joints Using FRP Sheets and Buckling Restrained Braces

2013 ◽  
Vol 479-480 ◽  
pp. 1170-1174
Author(s):  
Hee Cheul Kim ◽  
Dae Jin Kim ◽  
Min Sook Kim ◽  
Young Hak Lee

The purpose of this study was to evaluate seismic performance of rehabilitated beam-column joint using FRP sheets and Buckling Restrained Braces (BRBs) and provide test data related to rehabilitated beam-column joints in reinforced concrete structures. The seismic performance of total six beam-column specimens is evaluated under cyclic loadings in terms of shear strength, effective stiffness, energy dissipation and ductility. The test results showed wrapping FRP sheets can contribute to increase the effect of confinement and the crack delay. Also retrofitting buckling restrained braces (BRBs) can improve the stiffness and energy dissipation capacity. Both FRP sheets and BRBs can effectively improve the strength, stiffness and ductility of seismically deficient beam-column joints.

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Mingke Deng ◽  
Yangxi Zhang

This study mainly aims to investigate the effectiveness of high-ductile fiber-reinforced concrete (HDC) as a means to enhance the seismic performance of short columns. Six HDC short columns and one reinforced concrete (RC) short column were designed and tested under lateral cyclic loading. The influence of the material type (concrete or HDC), axial load, stirrup ratio, and shear span ratio on crack patterns, hysteresis behavior, shear strength, deformation capacity, energy dissipation, and stiffness degradation was presented and discussed, respectively. The test results show that the RC short column failed in brittle shear with poor energy dissipation, while using HDC to replace concrete can effectively improve the seismic behavior of the short columns. Compared with the RC short column, the shear strength of HDC specimens was improved by 12.6–30.2%, and the drift ratio and the energy dissipation increases were 56.9–88.5% and 237.7–336.7%, respectively, at the ultimate displacement. Additionally, the prediction model of the shear strength for RC columns based on GB50010-2010 (Chinese code) can be safely adopted to evaluate the shear strength of HDC short columns.


2013 ◽  
Vol 680 ◽  
pp. 234-238
Author(s):  
Jin Li Qiao ◽  
Wen Ling Tian ◽  
Ming Jie Zhou ◽  
Fang Lu Jiang ◽  
Kun Zhao

In order to validate the seismic performance of reinforced concrete grid-mesh frame wall , four grid frame walls in half size is made with different height-width ratios and different grid forms in the paper. Two of them are filling with cast-in-place plaster as filling material. According to the experimental results of these four walls subjected to horizontal reciprocating loads, we know that the grid-mesh frame wall's breaking form are in stages and multiple modes, and the main influencing factors are height-width ratio and grid form, what's more, with cast-in-place plaster as fill material, could not only improve the level of the wall bearing capacity and stiffness, but also improve the ductility and seismic energy dissipation capacity.


2012 ◽  
Vol 479-481 ◽  
pp. 170-173
Author(s):  
Yu Tian Wang ◽  
Fu Xiang Jiang ◽  
Yan Wang ◽  
Xiu Li Du

A single-span and two-story frame specimen with reinforced beam ends has been tested under low-frequency cyclic loading. Based on the test results, the failure patterns, hysteretic behaviors, energy dissipation and deformation ability were analyzed. The results showed that the failure mode of the test specimen was ductility. Plastic hinges appeared at the changing point of the beam cross section far away from the beam-column joint. Hysteretic curve of the frame was full and the whole ductility coefficient was enough higher than 4.4 under horizontal low-cyclic loading. It can be concluded that the energy dissipation and the deformation ability are both better. So the whole steel frame connected with reinforced beam ends has good seismic performance. And the requirements of anti-seismic ability can be satisfied.


2021 ◽  
Vol 60 (1) ◽  
pp. 818-838
Author(s):  
Haiou Shi ◽  
Jinxia Zhao ◽  
Fangmu Chen ◽  
Junjin Lin ◽  
Jianhe Xie

Abstract Precast-reinforced concrete (RC) structures in urban rail transit projects can provide many advantages over their cast-in-place counterparts. However, lessons learned from past earthquakes show that beam-column joints may be a critical point of these structures and can overestimate the mechanical performance under vertical seismic loadings if not properly understood. This paper presents unbonded and bonded prestressed precast RC beam-column joints for elevated station platforms. Prestressed steel strands are used to provide joints with self-centring capacity. The performance of the proposed joints under vertical cyclic loadings is experimentally investigated and compared to that of monolithic joints in this study. The obtained results demonstrate the good properties of the proposed precast joints in terms of bearing capacity, energy dissipation capacity and ductility control. A comparison with a conventional monolithic beam-column joint indicates the better performance against earthquakes of the proposed precast prestressed joints, and the precast joint with symmetric prestressed steel strands in the top and bottom of the beam exhibits better flexural stiffness and energy dissipation capacity.


2016 ◽  
Vol 20 (9) ◽  
pp. 1299-1314 ◽  
Author(s):  
Hongtao Liu ◽  
Qiushi Yan ◽  
Xiuli Du

Precast reinforced concrete structures are widely used due to many constructional advantages such as faster construction speed, lower construction cost, being environmentally friendly, higher strength, and so on. To study the seismic performance of precast reinforced concrete structures, tests on beam-to-column joints of precast reinforced concrete structures were conducted under low reversed cyclic loading. In total, four joint specimens were produced in this study, including two precast joints and two cast-in-place joints. In addition to the comparison between different types of joints, the axial compression ratio of column was adopted as the main variable in this study. Analysis was carried out on the basis of the observed joint failure mode and relationships derived from the test data such as hysteresis curves, skeleton curves, stiffness degradation curves, energy dissipation capacities, and sleeve joint strain curves. Despite the closeness of energy dissipation capacity between the precast joints and the cast-in-place joints, they had different failure modes. Precast joints feature a relatively concentrated crack distribution in which the limited number of cracks was distributed throughout the plastic zone of the beam. Cast-in-place joints feature more evenly distributed cracks in the plastic zone, especially at the later stage of the loading. The steel slippage of the precast concrete joints was found influenced by the axial compression ratio. Through this study, it is concluded that seismic resistance capacity of precast concrete joint needs to be considered in design and construction and the grouting sleeve splice could be kept away from the hinge zones when precast concrete structures were used in regions of high seismicity. The results in this study can provide a theoretical basis for seismic design of precast reinforced concrete structures, which in turn can promote the application of precast reinforced concrete structures.


2021 ◽  
Author(s):  
Shengcai Li ◽  
Shengxiang Shi ◽  
Zhongchen Zhou

In order to evaluate the influence of internal defects of semi-grouting sleeve connection on seismic performance of assembled monolithic columns, four specimens of assembled monolithic concrete column with semi grouting sleeve connecting reinforcement bar were fabricated with 10%, 20%, 30% internal defects. The test results show that (1) the assembled columns are all damaged by bending, the grouting layer of the assembled column can be pulled apart easily and the cracks develop more closely on the upper part of the sleeve; (2) the larger the internal defects in the sleeve, the less the cracks on the column, and the less sufficient the cracks development; (3) the seismic energy dissipation capacity of the column without defect is better than that of the defective columns.


2014 ◽  
Vol 08 (04) ◽  
pp. 1450012
Author(s):  
Haozhi Tan ◽  
Liang Huang ◽  
Libo Yan ◽  
Hongwei Yi ◽  
Xin Tian

Bracing is one of the most effective systems which is widely used to improve the seismic performance of reinforced concrete (RC) plane frames. However, studies on the use of bracing in newly constructed RC space frame (RCSF) are rare. This paper presents the experimental results of two 1/4-scale, two-story, and three-bay RCSFs under cyclic loading. A RCSF without brace was designed and constructed as a control system, which was termed as "RCSF". Another one was constructed and strengthened with steel X-braces, which was termed as "SBRCSF". The seismic performance of RCSF was compared with those of SBRCSF. The test results show that compared with the RCSF, the seismic performance of the SBRCSF was improved significantly in terms of hysteresis loop, strength, stiffness degradation, and energy dissipation capacity. In addition, unlike the inter-story failure mechanism of the RCSF, the SBRCSF specimen exhibited an overall failure mechanism, which is significant for the seismic design of RCSFs. Moreover, the tested SBRCSF could bear loads in a manner similar to that of untested RCSF after the failure of the steel braces, thereby revealing the redundancy of SBRCSF and showing the advantageous of the use of steel braces for space frame.


1996 ◽  
Vol 12 (4) ◽  
pp. 761-780 ◽  
Author(s):  
A. Ghobarah ◽  
Tarek S. Aziz ◽  
Ashraf Biddah

As building codes are updated, some of the existing important structures may fall short of complying with current standards even though they may have been properly designed and constructed according to earlier codes. Many existing structures may be inadequate and may pose severe risk during seismic events. Rehabilitation measures to upgrade the capacity of these structures can be performed at some point in their useful lives especially when located in seismically active zones. A new method for improving the seismic performance of existing reinforced concrete structures is by jacketing the deficient connections using corrugated steel jackets. An experimental program was conducted to evaluate this method of rehabilitation. Corrugated steel jacketing addresses the particular weakness that is often found in existing reinforced concrete structures, namely the lack of sufficient shear reinforcement and the required confining reinforcement within the joints and in adjoining beams and columns. The performance of four reinforced concrete connections was determined experimentally. The test specimens include one connection representing existing structures, one designed according to current seismic codes and two rehabilitated connections. The test results showed satisfactory performance at high cyclic load levels and significant increase in the shear capacity and ductility of connections rehabilitated with corrugated steel jackets.


2021 ◽  
Author(s):  
Mohana R

Abstract Ductility and energy dissipation capacity of the beam column joints are the two prominent characteristics which governs the stability of the entire structure constructed in the seismic prone areas. In this paper, the effect of potassium activated geopolymer concrete in the exterior beam column joint application is investigated under low frequency cyclic loading. Numerical analysis has been done by using the finite element software Abaqus and compared with the experimental work. From the load deformation relationship, parametric studies are carried out in the aspects of ductility, stiffness degradation, energy dissipation capacity, drift ratio and cracking pattern. The use of potassium activated geopolymer technology in the exterior beam column joint application resulted in the improved ductility, energy dissipation capacity with superior ultimate load carrying capacity of 1.05% over conventional cement reinforced concrete beam column joints with special confining reinforcement confirmed by IS 13920 due to the enormous polymerisation activated by high molecular potassium ions.2.78% improved energy dissipation capacity of potassium based geopolymer specimen resulted in the lesser number of non structural cracks and 11.26% more deformation under 11.96% enlarged drift ratio than the conventional reinforced concrete specimen. From the observed results it is clearly noted that the implementation potassium activated green polymer technology in the beam column joints possessed enhanced ductility characteristics to protect the structure susceptible to seismic environment and resulted in the innovative, economical and sustainable mode of seismic resistant building construction.


2013 ◽  
Vol 859 ◽  
pp. 95-99
Author(s):  
Yan Zhao ◽  
Hong Yu Jiang ◽  
Jie Gu ◽  
Ru Qin Wang

Hollow rectangular reinforced concrete piers have been widely used in tall-column and long-span bridges. Two large-scale experimental models of the hollow reinforced concrete bridge piers were built to study the seismic performance of the piers subjected to biaxial bending under constant axial load. The objective is to evaluate seismic performances of the model piers and the factors affecting the seismic performance of the model piers by comparing their failure mechanism, bearing capacity, ductility, energy dissipation capacity, etc. The results show that the hollow rectangular specimen experienced flexural failure with plastic hinges formed at the bottom of the piers when subjected to combined axial load and biaxial bending. The bearing capacity of the specimen increases greatly and the ductility decrease insignificantly as the axial compression ratio increases from 0.1 to 0.2, while the energy dissipation capacity is increased by 121.8%, however, the absolute value of total cumulative hysteretic energy is not magnificent.


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