A Hysteretic Model of Conventional Steel Braces and an Analysis of the Collapse Prevention Effect of Brace Strengthening

2012 ◽  
Vol 174-177 ◽  
pp. 3-10 ◽  
Author(s):  
Sheng Nan Huang ◽  
Xin Zheng Lu ◽  
Lie Ping Ye
Keyword(s):  
Dynamic Analysis ◽  
Incremental Dynamic Analysis ◽  
Hysteretic Behavior ◽  
Fragility Analysis ◽  
Strengthening Effect ◽  
Rc Frame ◽  
Hysteretic Model ◽  
Collapse Prevention ◽  
Conventional Steel ◽  
Rc Frames

A hysteretic model of conventional steel braces consisting of 18 parameters is proposed. This model is able to simulate the hysteretic behavior of conventional steel braces accurately. The collapse-prevention strengthening effect with steel braces for a typical reinforced concrete (RC) frame that was close to the epicenter and collapsed during the Great Wenchuan Earthquake is discussed via push-over analysis and collapse fragility analysis based on incremental dynamic analysis. The result could be referred to for the seismic collapse prevention design of RC frames.

Study on the Strengthening Effect of a Typical RC Frame in Wenchuan Earthquake with Attached Substructures

2013 ◽  
Vol 353-356 ◽  
pp. 2057-2064
Author(s):  
Sheng Nan Huang ◽  
Xin Zheng Lu ◽  
Lie Ping Ye
Keyword(s):  
Wenchuan Earthquake ◽  
Incremental Dynamic Analysis ◽  
Critical Parameters ◽  
Strengthening Effect ◽  
Rc Frame ◽  
Viscous Damper ◽  
Buckling Restrained Brace ◽  
The Wenchuan Earthquake ◽  
Collapse Resistance ◽  
Better Than

This work is based on a typical RC frame that was closed to the epicenter and collapsed during the Wenchuan Earthquake. The seismic collapse resistance of the frame was strengthened by attached substructures, including conventional brace, buckling restrained brace (BRB) and viscous damper. Collapse fragility analysis based on incremental dynamic analysis is implemented for each strengthening scheme to compare their effects and to analyze the influence of critical parameters. The results show that the viscous damper performs better than the BRB, and the BRB performs better than the conventional brace. With the same strengthening parameters, the A-shaped bracing scheme is better than the X-shaped scheme.

Fragility analysis of a subway station structure by incremental dynamic analysis

2016 ◽  
Vol 20 (7) ◽  
pp. 1111-1124 ◽  
Author(s):  
Tong Liu ◽  
Zhiyi Chen ◽  
Yong Yuan ◽  
Xiaoyun Shao
Keyword(s):  
Dynamic Analysis ◽  
Earthquake Engineering ◽  
Seismic Vulnerability ◽  
Probabilistic Method ◽  
Incremental Dynamic Analysis ◽  
Seismic Intensity ◽  
Fragility Analysis ◽  
Subway Station ◽  
Limit States ◽  
Station Structure

Fragility analysis constitutes the basis in seismic risk assessment and performance-based earthquake engineering during which the probability of a structure response exceeding a certain limit state at a given seismic intensity is sought to relate seismic intensity and structural vulnerability. In this article, the seismic vulnerability assessment of a subway station structure is investigated using a probabilistic method. The Daikai subway station was selected as an example structure and its seismic responses are modeled according to the nonlinear incremental dynamic analysis procedure. The limit states are defined in terms of the deformation and waterproof performance of the subway station structure based on the central column drift angle and the structural tension damage distribution obtained from the incremental dynamic analysis. Fragility curves were developed at those limit states and the probability of exceedance at the limit states of operational, slight damage, life safety, and collapse prevention was determined for the two seismic hazard levels. Results reveal that the proposed fragility analysis implementation procedure to the subway station structure provides an effective and reliable seismic vulnerability analysis method, which is essential for these underground structural systems considering their high potential risk during seismic events.

scholarly journals Strengthening of Precast RC Frame to Mitigate Progressive Collapse by Externally Anchored Carbon Fiber Ropes

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1306
Author(s):  
Jianwu Pan ◽  
Xian Wang ◽  
Hao Dong
Keyword(s):  
Carbon Fiber ◽  
Load Capacity ◽  
Progressive Collapse ◽  
Analytical Models ◽  
Deformation Condition ◽  
Strengthening Effect ◽  
Rc Frame ◽  
Catenary Action ◽  
Rc Frames ◽  
Collapse Failure

The robustness of precast reinforced concrete (RC) frames is relatively poor, while the precast RC frames are strengthened to mitigate progressive collapse, avoiding “strong beams and weak columns” and the anchorage failure of strengthening materials under large deformation condition are the key problems. Aiming to discuss these problems, this paper carried out an experimental research of strengthening on three half-scale assembled monolithic frame subassemblages to mitigate progressive collapse. One specimen was strengthened by implanting carbon fiber rope (CFR) with polymer into concrete, one specimen was strengthened by binding CFR with special knot, and the last one was not strengthened. The failure mode, collapse failure mechanism and strengthening effect of subassemblages were discussed. Analytical models of load capacity increment contributed by CFR and construction suggestions of precast RC frame to mitigate progressive collapse were proposed. The results indicated that none of the strengthened specimens had anchorage failure. The two strengthening methods significantly increased the load capacity of the subassemblages in the catenary action (CA) stage with little effect on the flexural action (FA) stage and compressive arch action (CAA) stage.

Lateral Load Behavior of an Open-Ground-Story RC Building with AAC Infills in Upper Stories

2016 ◽  
Vol 32 (3) ◽  
pp. 1653-1674 ◽  
Author(s):  
Supratik Bose ◽  
Durgesh C. Rai
Keyword(s):  
Brick Masonry ◽  
Hysteretic Behavior ◽  
Analytical Models ◽  
Rc Frame ◽  
Masonry Infills ◽  
Rc Frames ◽  
Open Ground ◽  
Strength And Stiffness ◽  
Infilled Rc Frames ◽  
Masonry Infilled Rc Frames

Autoclaved aerated concrete (AAC) masonry infills in upper stories can be beneficial for improving the seismic response of open-ground-story (OGS), reinforced concrete (RC)–frame buildings. Two reduced 1:2.5-scale models of single-story, single-bay RC frames with and without AAC infill masonry were tested for resistance properties and hysteretic behavior. Low strength and stiffness of AAC masonry, about half of the conventional brick masonry, led to improved load sharing between the infill and the frame, which helped an early development of frame yield mechanism for enhanced energy dissipation. Test results were used to evaluate the reliability of using existing strength and stiffness relations of conventional masonry infilled RC frames for AAC infilled frames. Analytical models were developed to predict the observed hysteretic behavior of tested specimens. Nonlinear analyses of a five-story, four-bay OGS-RC frame were performed for conventional brick masonry infills and relatively softer and weaker AAC infills in upper stories. The results indicated that the undesirable effect of weak/soft ground story mechanism of OGS-RC frames can be reduced to an acceptable level by using AAC infills in upper stories.

An RHT-Model-Based Equivalent Parameter Scheme for Blast Response Simulation of RC Frames

2021 ◽  
Author(s):  
Ziqi Tang ◽  
Shanglin Yang ◽  
Run Zhang ◽  
Xiaohu Yao
Keyword(s):  
Response Analysis ◽  
Strengthening Effect ◽  
Rc Frame ◽  
Model Based ◽  
Rc Frames ◽  
Multiple Components ◽  
Equivalent Parameter ◽  
Blast Response ◽  
Constitutive Parameters ◽  
Parameter Scheme

In this paper, a novel equivalent parameter scheme based on the Riedel–Hiermaier–Thoma (RHT) model is proposed for blast response simulations of reinforced concrete (RC) frames. Considering the strengthening effect of longitudinal and stirrup reinforcements on concretes, constitutive parameters in the RHT model are modified to homogenize RC components based on reasonable simplifications and numerical tests. Numerical results of RC beams illustrate that this scheme significantly improves the computational efficiency and effectively predicts real explosion response behaviors with high accuracy. The scheme is then employed for the blast simulation of an RC frame with multiple components with results compared with those of real frame experiments to further demonstrate its reliability. Owing to its efficiency and accuracy, the present RHT-model-based equivalent parameter scheme can serve as a feasible tool to conduct blast response analysis of the RC frame and guide the corresponding anti-explosion designs.

Restoring Force Model of Joints of RC Frame Retrofitted by FRP

2012 ◽  
Vol 256-259 ◽  
pp. 693-696
Author(s):  
Peng Li ◽  
Ya Ping Peng ◽  
Er Lei Yao
Keyword(s):  
Seismic Performance ◽  
Seismic Retrofitting ◽  
Frame Structure ◽  
Force Model ◽  
Strengthening Effect ◽  
Rc Frame ◽  
Restoring Force ◽  
Rc Frames ◽  
Restoring Force Model ◽  
Hysteretic Performance

In order to evaluate the seismic performance of reinforced concrete (RC) frames retrofitted by FRP, the experiment of RC frames retrofitted at joints by FRP was carried out. The enhancement in seismic performance of the retrofitted frames is evaluated in hysteretic performance, bearing capacity, stiffness degradation and energy dissipation. And the strengthening effect of the frame retrofitted by CFRP and C/GFRP was compared in the experiment. The restoring force model of RC frame joints retrofitted with FRP was proposed and ranges of the characteristic parameters were determined. The equation of restoring force model for joints strengthened by C/GFRP was suggested. The result show that seismic performance of RC frame retrofitted by FRP based on joints can be improved remarkably. The restoring force model which proposed can be used in seismic elasto-plastic analysis of RC frame structure retrofitted by FRP and practical engineering seismic retrofitting design by FRP.

scholarly journals Seismic fragility analysis of pre-1975 conventional concrete frame buildings in Canada

2018 ◽  
Vol 45 (9) ◽  
pp. 728-738 ◽  
Author(s):  
Abdullah Al Mamun ◽  
Murat Saatcioglu
Keyword(s):  
Dynamic Analysis ◽  
Seismic Vulnerability ◽  
Time History ◽  
Incremental Dynamic Analysis ◽  
Assessment Tools ◽  
Fragility Analysis ◽  
Reinforced Concrete Frame ◽  
Earthquake Intensity ◽  
Concrete Frame ◽  
Frame Buildings

Fragility analysis was conducted for reinforced concrete frame buildings in Canada designed based on the 1965 National Building Code of Canada as representative of pre-1975 era of seismic design practice. Two-, five-, and ten-storey buildings were designed for Vancouver and Ottawa, representing buildings in high and medium seismic regions. They were modelled for inelastic response time history analysis, with respective inelastic hysteretic models for flexure and shear. Software PERFORM-3D was used to conduct incremental dynamic analysis under incrementally increasing earthquake intensity. Probabilistic analysis of the results of incremental dynamic analysis led to the development of fragility functions, which can be used as seismic vulnerability assessment tools. The results are compared with those generated for frame buildings designed on the basis of the 2010 NBCC. The comparison indicates that the probabilities of exceeding performance levels are significantly higher for older buildings relative to recently built fully ductile and moderately ductile buildings, respectively.

Sign in / Sign up

Export Citation Format

Share Document