scholarly journals Evaluation of the Seismic Retrofitting of Mainshock-Damaged Reinforced Concrete Frame Structure Using Steel Braces with Soft Steel Dampers

2021 ◽  
Vol 11 (2) ◽  
pp. 841
Author(s):  
Fujian Yang ◽  
Guoxin Wang ◽  
Mingxin Li
Keyword(s):  
Reinforced Concrete ◽  
Structural Damage ◽  
Time History ◽  
Evaluation Framework ◽  
Seismic Retrofitting ◽  
Frame Structure ◽  
Rc Frame ◽  
Severe Damage ◽  
Rc Frames ◽  
Better Than

Most reinforced concrete (RC) frames would exhibit different degrees of damage after mainshock excitations, and these mainshock-damaged RC (MD-RC) frames are highly vulnerable to severe damage or even complete collapse under aftershock excitations. In the present study, the effectiveness of utilizing soft steel damper (SSD) as a passive energy dissipation device for seismic retrofitting of MD-RC frame under aftershock actions was investigated. A common three-story RC frame in the rural area was employed and a numerical evaluation framework of retrofitting analysis of the MD-RC frame was also proposed. Based on proposed evaluation framework, nonlinear dynamic time history analysis of the MD-RC frame with and without retrofitting schemes was conducted to evaluate the retrofit effect of the retrofitting schemes on the MD-RC frame. The results revealed that the retrofitting schemes could effectively improve the natural vibration characteristics of the MD-RC frame, especially the first-order natural frequency with a maximum increase of nearly four times. The retrofit effect of the MD-RC frame under pulse-like aftershocks is better than non-pulse-like aftershocks and the retrofit effect of minor damage MD-RC frame is slightly better than that of severe damage. In addition, only retrofitting the bottom story of MD-RC frame might cause aggravate structural damage.

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.

Metaheuristic Optimization of Reinforced Concrete Frames

2020 ◽  
pp. 141-160
Keyword(s):  
Reinforced Concrete ◽  
Optimum Design ◽  
Harmony Search ◽  
Time History ◽  
Rc Frame ◽  
Concrete Frames ◽  
Design Constraints ◽  
Rc Frames ◽  
History Analysis ◽  
Internal Forces

In this chapter, an optimum design methodology for reinforced concrete (RC) frames are presented. In the optimum design of frames, both beams and columns are optimized. In addition to that, internal forces can be modified according to rigidity of members for statically indetermined frames. In the presented methodology, the optimization of RC frame is done according to dynamic seismic loads and the design is done according to time-history analysis. As a metaheuristic algorithm, a modified harmony search is used, and the design constraints are provided according to ACI 318: Building code requirements for structural concrete. The optimum results of two span-two story symmetric RC frames and three span-three story RC frame are presented.

The Lima earthquake of October 3, 1974: Damage distribution

1977 ◽  
Vol 67 (5) ◽  
pp. 1441-1472
Author(s):  
R. Husid ◽  
A. F. Espinosa ◽  
J. de las Casas
Keyword(s):  
Reinforced Concrete ◽  
Structural Damage ◽  
Concrete Structures ◽  
Effective Length ◽  
Reinforced Concrete Structures ◽  
Severe Damage ◽  
Original Design ◽  
Reinforced Masonry ◽  
Water Tanks ◽  
Story Building

abstract The October 3, 1974, earthquake caused severe damage to buildings of adobe and quincha construction, and also to masonry, reinforced masonry, and reinforced-concrete structures in Lima and vicinity. Most of the damage to well-built structures was due, in part, to the lack of lateral resistance in the original design and to the fact that this earthquake had more energy around 0.4 seconds period than prior destructive earthquakes. Water tanks on the roofs of structures with four or five stories were damaged. Well-engineered single-story buildings were less affected than taller structures. Considerable structural damage to reinforced-concrete structures occurred in the districts of Barranco, La Campiña Molina, and Callao. In La Campiña three-story building partly collapsed and other buildings sustained considerable damage. In La Molina, the buildings of the Agrarian University sustained severe damage, and some collapsed. In Surco, the district adjacent to La Molina, there was no appreciable damage. In Callao, a four-story building collapsed, and the upper half of a concrete silo collapsed. In reinforced-concrete structures, column ties were frequently small in diameter, widely spaced, and not well connected. Usually, the reinforcement of resisting elements had no relation to their stiffnesses. Front columns in school buildings were restrained by high brick walls and had rather short effective lengths to allow building displacement in that direction. The windows in the rear walls gave the rear columns a much greater effective length. Therefore, a longitudinal displacement induces large shear forces in the front columns where most of the severe damage occurred. This problem was not considered in the design of these structures.

Research on the Collapse Performance of RC Frame Structure

2014 ◽  
Vol 556-562 ◽  
pp. 712-715
Author(s):  
Jing Zhao ◽  
Jing Zhao ◽  
Xing Wang Liu
Keyword(s):  
Reinforced Concrete ◽  
Frame Structure ◽  
Rc Frame ◽  
Hydraulic Actuator ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Load Paths ◽  
Rc Frame Structure ◽  
Gravity Load ◽  
Middle Column

In collapse-resistant design of a structure under accidental local action, it is important to understand the failure mechanism and alternative load paths. In this paper, a pseudo-static experimental method is proposed. Based on which, the collapse of frame structure was simulated with testing a 1/3 scale; 4-bay and 3-story plane reinforced concrete frame. In the experience, the middle column of the bottom floor was replaced by mechanical jacks to simulate its failure, and the simulated superstructure’s gravity load acted on the column of the top floor by adopting a servo-hydraulic actuator with force –controlled mode.

Nonlinear Analysis of a RC Frame Structure with Semi-Interlayers Damaged during Wenchuan Earthquake

2010 ◽  
Vol 156-157 ◽  
pp. 467-472
Author(s):  
Peng Tao Yu ◽  
Jing Jiang Sun
Keyword(s):  
Nonlinear Analysis ◽  
Wenchuan Earthquake ◽  
Time History ◽  
Large Earthquake ◽  
Frame Structure ◽  
Nonlinear Time History Analysis ◽  
Frame Structures ◽  
Rc Frame ◽  
Rc Frame Structures ◽  
Nonlinear Time History

Under the excitation of large earthquake, structures enter into high nonlinear stage. Currently, Opensees, Perform-3d and Canny are used as the most popular nonlinear analysis procedures. The fiber model will be introduced firstly and the nonlinear analysis models in Canny are explained in detail. Then Canny2007 is used to conduct nonlinear time history analysis on a heavily damaged frame structure with interlayer in Dujiangyan during Wenchuan Earthquake. Analysis shows that the maximum inter-story drift appears between the interlayer and its upper layer, and the heavy damage agrees well with the results of damage investigation. By comparing the damage extent of frame structures with or without interlayer, it reveals that the seismic performance of RC frame structures without interlayer is obviously better than that of ones with interlayer.

Seismic Damage Analysis and the Study of Reinforcement Measures for RC Frame Structure Building in Civil Engineering

2012 ◽  
Vol 568 ◽  
pp. 85-88
Author(s):  
Ming Gao
Keyword(s):  
Structural Damage ◽  
Civil Engineering ◽  
Seismic Damage ◽  
Frame Structure ◽  
Bottom Plate ◽  
Rc Frame ◽  
Structure Building ◽  
Damage Degree ◽  
Rc Frame Structure ◽  
Reinforcement Measures

In 5·12 Wenchuan earthquake, most of the buildings were damaged at different degrees in Mianyang. To analysis seismic damage of RC frame structure building, and investigate its reinforcement situation，the results show that: For destruction of frame column or bottom frame structure column, enlarge section method is used mostly for reinforcement in civil engineering；To serious damage of affiliated structure such as filler wall and Parapet, most of them will be demolished and built again, and add constructional column; To the situation of concrete bottom plate with crack, paste carbon fiber sheet or bottom plant steel was used depending on the structural damage degree, and jet concrete for strengthening.

scholarly journals Rapid Retrofit of Reinforced Concrete Frames after Progressive Collapse to Increase Sustainability

2019 ◽  
Vol 11 (15) ◽  
pp. 4195 ◽  
Author(s):  
Li ◽  
Shan ◽  
Zhang ◽  
Li
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Design Method ◽  
Numerical Models ◽  
Progressive Collapse ◽  
Frame Structure ◽  
Rc Frame ◽  
Concrete Frames ◽  
Before And After ◽  
Test Frame

A structural progressive collapse is usually a local failure, in which the damage is concentrated at beams that bridge the removal column and the column itself. In many cases, retrofitting the damaged structure is more economical and more sustainable than reconstructing the entire structure. A progressive collapse test of a 1/3 scale, four-bay by two-story reinforced concrete (RC) frame was conducted, after which the structure was retrofitted with carbon fiber reinforced polymer (CFRP) wraps and retested. The center column in the first story was removed and the frame was pushed down quasistatically under displacement control to investigate the progressive collapse performances of the retrofitted RC frame. The test results were represented systematically at different areas in terms of the resistance forces, crack developments, and local and global failure modes. Numerical models were built to verify the test frame before and after the retrofitting. A design method was proposed to retrofit an RC frame using CFRP wraps after a progressive collapse. The test frame was redesigned to improve the retrofitting and used as an example to demonstrate the rationality of the proposed retrofit design method. The results indicated that the proposed retrofitting technology rapidly restored the frame structure to its original capacity before the progressive collapse occurred, whilst consistently satisfying the priorities of being economical and sustainable.

The influence of construction joint on the seismic behavior of reinforced concrete frame structure

2016 ◽  
Vol 20 (7) ◽  
pp. 1125-1138 ◽  
Author(s):  
Jing Yu ◽  
Xiaojun Liu ◽  
Xingwen Liang
Keyword(s):  
Reinforced Concrete ◽  
Seismic Behavior ◽  
Numerical Models ◽  
Time History ◽  
Frame Structure ◽  
Nonlinear Time History Analysis ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Construction Joint ◽  
Story Drift

A new model that can simulate the behavior of construction joint subjected to seismic forces was proposed. Nonlinear time-history analysis was carried out for reinforced concrete regular frame structures designed in different seismic intensity regions as well as with different height-to-width ratios. Two kinds of numerical models are adopted to simulate the seismic behavior of each frame, one with construction joint using the new proposed model and the other without construction joint using the conventional model. Results show that the influence of construction joint on the seismic behavior of reinforced concrete frame is strongly related to structural nonlinearity. It may increase the top displacement and the inter-story drift, change the inter-story drift distributions, and exacerbated the local reaction of key members. The influence of construction joint cannot be ignored for structures with low emergency capacity against major earthquake. Seismic design suggestions are proposed from the aspect of calculation analysis method.

A Study on Dissipation of Cumulative Hysteretic Energy in Reinforced Concrete Frame Structures

2010 ◽  
Vol 163-167 ◽  
pp. 4301-4308
Author(s):  
Min Sheng Guan ◽  
Da Jian Han ◽  
Hong Biao Du ◽  
Xin Wang
Keyword(s):  
Reinforced Concrete ◽  
Distribution Pattern ◽  
Ground Motion ◽  
Time History ◽  
Frame Structure ◽  
Input Energy ◽  
Reinforced Concrete Frame ◽  
Hysteretic Energy ◽  
Concrete Frame ◽  
Reinforced Concrete Frame Structures

Earthquake input energy and structural energy dissipation are key indicators to assess the seismic performance of structures. To study the rules of distribution of hysteretic energy within structures, a 6-storey regular reinforced concrete frame structure model is analyzed through elasto-plastic time-history dynamic analysis using the El Centro and Northridge accelerograms. Based on the comparison between numerical results for the earthquake input energy and structural hysteretic energy under the minor, moderate and major earthquakes of Grade 8 and 9, the distribution of the ratio of the storey hysteretic energy to the total hysteretic energy through the height was further studied. It shows that the computed results corresponding to the two earthquake records are in good agreement under different ground motion severity. And the percentage of structural hysteretic energy to input energy is basically stable. The distribution pattern of storey hysteretic energy through the height is that the value of the upper stories is smaller than the value of the lower stories. And the ground motion severity has a minor influence on the distribution pattern when the plasticity of structure develops more sufficiently.

scholarly journals Analysis and design of a base-isolated reinforced concrete frame building

1978 ◽  
Vol 11 (4) ◽  
pp. 245-254 ◽  
Author(s):  
L. M. Megget
Keyword(s):  
Reinforced Concrete ◽  
Plastic Hinge ◽  
Time History ◽  
Frame Structure ◽  
Reinforced Concrete Frame ◽  
Elastomeric Bearings ◽  
Analysis And Design ◽  
Concrete Frame ◽  
Frame Building ◽  
Reinforced Concrete Frame Structure

The paper describes the dynamic and static analyses and design of a four storey ductile reinforced concrete frame structure isolated from the foundations by elastomeric bearings incorporating lead energy dampers. Results from inelastic, time-history analyses for the isolated and non-isolated structure are compared for several input earthquake motions. The benefits of energy dampers in reducing the isolated building's response (shears, plastic hinge demands and interstorey drifts) are detailed. Differences from conventional ductile design and detailing as well as design recommendations are included.

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