Concentrated plasticity modelling of RC frames in time-history analyses

2021 ◽  
Vol 243 ◽  
pp. 112716
Author(s):  
Eleonora Bruschi ◽  
Paolo M. Calvi ◽  
Virginio Quaglini
Keyword(s):  
Time History ◽  
Rc Frames

Investigation of Damages in RC Frames Under Near Field Earthquakes Using a Damage Index

2016 ◽  
Vol 16 (02) ◽  
pp. 1450094 ◽  
Author(s):  
Seyed Morteza Zinati Yazdi ◽  
Mohammad Taghi Kazemi
Keyword(s):  
Near Field ◽  
Damage Index ◽  
Time History ◽  
General Rule ◽  
Nonlinear Time History Analysis ◽  
Far Field ◽  
Moment Frames ◽  
Moment Frame ◽  
Rc Frames ◽  
Nonlinear Time History

Heavy damages on structures caused by near field earthquakes in recent years has brought serious attention to this problem. An examination of previous records has shown significant differences for near field earthquakes, including a large energy pulse, unlike far field earthquakes. But as a general rule, the effects of near field earthquakes have been ignored in most building codes. The purpose of this paper is to investigate the effect of near field earthquakes on reinforced concrete (RC) moment frames. To achieve this goal, the Erduran damage index, an efficient way to calculate damage, was employed to analyze two 4- and 8-story RC moment frame buildings. The buildings with moderate and high ductility were designed by the strength criteria. Seven pairs of near field and far field earthquakes were scaled and used for dynamic nonlinear time history analysis. Using Erduran’s beam and column damage index, respectively, based on rotation and drift, the results from both near and far field earthquakes were compared. Moreover, for better assessment, 4-story buildings were evaluated from the performance based viewpoint of design. We observe from the results that most of the components of the structures under near field earthquakes sustained severe damages and in some cases even component failure. Components of the structures under near field earthquakes suffered from 30% more of damage, on average, than that under far field earthquakes.

An Investigation of Vector Intensity Measures for Seismic Collapse Assessment Under Far-Field Aftershocks

2020 ◽  
pp. 2150004
Author(s):  
F. Soleiman Meigooni ◽  
M. Tehranizadeh
Keyword(s):  
Seismic Response ◽  
Time History ◽  
Considerable Effect ◽  
Far Field ◽  
Spectral Acceleration ◽  
Intensity Measures ◽  
Rc Frames ◽  
Seismic Collapse ◽  
Collapse Assessment

Aftershock records have a considerable effect on the results of collapse assessments conducted on buildings. Thus, they should be selected cautiously. As the number of recorded aftershocks is not sufficient, mainshock records are often utilized instead. In order to increase the correlation between the aftershock time history and the seismic response of a structure, this research intends to investigate several Intensity Measures (IMs). For this study, three RC frames were considered. Forty-four far-field records from FEMAP-695 were selected as main and aftershock. Each building analysis was conducted under 44 mainshock–aftershock chains. According to the results, use of the summation of the first mode spectral acceleration value of aftershocks as the second part of a vector IM can lead to the sufficiency of the IM.

scholarly journals Analytical Assessment of the Effect of Vertical Ground Motion on RC Frames Designed for Gravity Loads with Various Geometric Configurations

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Siyun Kim ◽  
Sung Jig Kim ◽  
Chunho Chang
Keyword(s):  
Ground Motion ◽  
Axial Force ◽  
Local Level ◽  
Time History ◽  
Analytical Investigation ◽  
Shear Capacity ◽  
Rc Frames ◽  
Geometric Configurations ◽  
Vertical Ground Motion ◽  
Vertical Ground

The paper presents an analytical investigation of the effect of vertical ground motion on the selected 13 reinforced concrete (RC) frames with different geometric configurations. For this purpose, earthquake ground motions with various vertical-to-horizontal peak acceleration ratios are selected to which a suitable scale factor is applied to match with seismic hazards of Korea. The methodology involves the evaluation of the structural responses of RC frames subjected to the selected records by means of nonlinear time history analyses. The results from the analysis are compared with results from studies of the case of horizontal-only excitation. The effect of the vertical earthquake component on damage of RC frames is considered at both the global and the local levels. The effect of vertical ground motion on axial force, shear demand, and shear capacity of RC columns is investigated to assess failure on a local level. In particular, the shear capacity is evaluated by using both the conservative method of a design code and more realistic predictive approaches. The results of the extensive analyses indicate that vertical ground motion can significantly affect the response of RC members in terms of axial force variation and shear capacity. These results point to the conclusion that vertical ground motion needs to be included in analysis for assessment and design.

scholarly journals Quasistatic Seismic Damage Indicators for RC Structures from Dissipating Energies in Tangential Subspaces

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Wilfried B. Krätzig ◽  
Yuri S. Petryna
Keyword(s):  
Structural Damage ◽  
Low Cycle Fatigue ◽  
Time History ◽  
Seismic Damage ◽  
Rc Structures ◽  
Rc Frames ◽  
Tangential Stiffness ◽  
Damage Indicators ◽  
Performance Based Seismic Design ◽  
Nonlinear Time History

This paper applies recent research on structural damage description to earthquake-resistant design concepts. Based on the primary design aim of life safety, this work adopts the necessity of additional protection aims for property, installation, and equipment. This requires the definition of damage indicators, which are able to quantify the arising structural damage. As in present design, it applies nonlinear quasistatic (pushover) concepts due to code provisions as simplified dynamic design tools. Substituting so nonlinear time-history analyses, seismic low-cycle fatigue of RC structures is approximated in similar manner. The treatment will be embedded into a finite element environment, and the tangential stiffness matrixKTin tangential subspaces then is identified as the most general entry for structural damage information. Its spectra of eigenvaluesλior natural frequenciesωiof the structure serve to derive damage indicatorsDi, applicable to quasistatic evaluation of seismic damage. Because detKT=0denotes structural failure, such damage indicators range from virgin situationDi=0to failureDi=1and thus correspond with Femaproposals on performance-based seismic design. Finally, the developed concept is checked by reanalyses of two experimentally investigated RC frames.

Seismic Vulnerability Analysis of Reinforced Concrete Frames with Mild Steel Dampers

2011 ◽  
Vol 368-373 ◽  
pp. 1526-1530 ◽  
Author(s):  
Jian Zhu ◽  
Ping Tan
Keyword(s):  
Reinforced Concrete ◽  
Mild Steel ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Response Spectrum ◽  
Time History ◽  
Concrete Frames ◽  
Rc Frames ◽  
History Analysis ◽  
Reduction Effect

This study focus on derivation of such fragility curves using conventional old reinforced concrete (RC) frames with Mild Steel Damper (MSD) of flexural energy dissipation braces. A set of stochastic earthquake waves compatible with the response spectrum of China seismic code selected to represent the variability in ground motion. Dynamic inelastic time history analysis was used to analyze the random sample of structures. Weak position was be pointed out, The result reveal that excellent reduction effect for structure of MSD is favorable and obvious under major earthquake.

scholarly journals Study on The Effect of Soft Story on Infill RC Frames Under Seismic Effect

2018 ◽  
Vol 13 (2) ◽  
pp. 79-91
Author(s):  
Mahesh Raj Bhatt ◽  
Prachand Man Pradhan ◽  
Sudip Jha
Keyword(s):  
Load Transfer ◽  
Linear Time ◽  
Time History ◽  
Seismic Demand ◽  
Bottom Part ◽  
Infill Wall ◽  
Analysis And Design ◽  
Soft Story ◽  
Regular Frame ◽  
Rc Frames

Construction practice of reinforced concrete (RC) frames infilled with unreinforced masonry is quite common now-days in urban cities in Nepal and elsewhere. Previous study shows the lateral load transfer mechanism is different than that of bare frames in infill buildings. Because of the unavoidable circumstances like elimination of central columns, elimination of infill wall in basement for parking purpose and reducing the size of frame members etc. may cause the particular story to be soft.In this study the infill RC frames with stiffness irregularity has been analysed with linear time history method using Gorkha-2015 earthquake as ground motion using structural analysis and design software (ETABS 2000 V.16). In total 8-numbers of 6-story RC infilled frames were analysed introducing the soft story in each story level respectively from basement to top. Regular frame was designed as per IS 1893:2002 load combination considering torsional effect. After analyse of bare frame, regular frame and irregular frames the global and story level seismic demand parameters were studied comparatively. Base/Story shear, Story displacement, inter-story drift and fundamental time period were the parameters compared taking regular frame as reference case.Results showed that, there is significant effect of location of irregularity on the seismic demand. The global and story level seismic demand is higher when the irregularity is introduced in bottom part of the buildings and further it showed that the lateral strength of RC frames get highly enhanced due to introductions of infill in analytical models.Kathmandu University Journal of Science, Engineering and TechnologyVol. 13, No. 2, 2017, page:79-91

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.

scholarly journals Seismic assessment of tall RC frames with hybrid friction damper and SMA designed by PBPD method

2021 ◽  
Vol 37 (1) ◽  
Author(s):  
F. Norouzi ◽  
H. Nasebaradi ◽  
M. Jamshidi
Keyword(s):  
Design Method ◽  
Time History ◽  
Hysteretic Behavior ◽  
Nonlinear Time History Analysis ◽  
Friction Damper ◽  
High Rise ◽  
Rc Frames ◽  
Lateral Strength ◽  
Residual Deformations ◽  
Nonlinear Time History

In this study, a new lateral load resisting system for high-rise (Reinforced Concrete) RC frames is proposed, which includes friction damper-superelastic SMA wires. The proposed SMA-friction damper can not only regulate the mechanism of frictional energy dissipation components with its self-centering SMA wires according to the design method based on the proposed performance, which is able to provide a hysteretic behavior and high self-centering capacity with the lowest SMA consumption but also has some advantages such as simple configuration and economic application. In this paper, two high-rise 18 and 22-story RC frames were designed in two design modes of common and with the proposed damper. The nonlinear time history analysis subjected to 10 far-field earthquakes performed in Opensees software. The results of the analyses showed that using the proposed SMA-friction damper, in addition to the effective increase in ductility, lateral stiffness and lateral strength, provided an excellent self-centering capacity, which resulted to the significant reduction in the maximum drift and the residual deformations in the structure.

COMPARISON OF DIFFERENT METHODS FOR VISCOUS DAMPER PLACEMENT IN EXISTING FRAME BUILDINGS

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Luca Landi ◽  
Filippo Conti ◽  
Pier Paolo Diotallevi
Keyword(s):  
Case Studies ◽  
Damping Ratio ◽  
Time History ◽  
Nonlinear Behavior ◽  
Concrete Frames ◽  
Viscous Dampers ◽  
Fluid Viscous Dampers ◽  
Rc Frames ◽  
Vertical Distributions ◽  
Nonlinear Dynamic Analyses

The main purpose of this research is to investigate the effects of different vertical distributions of the properties of nonlinear fluid-viscous dampers for the retrofit of existing multi-story reinforced concrete frames. In particular, the different distributions are defined on the basis of the same value of the supplemental damping ratio. Since the viscous dampers are used for the retrofit of existing buildings, they are dimensioned assuming that the structure can exceed the elastic limit, with the only condition to satisfy the prefixed performance limit. In the design phase the different vertical distributions of damper properties are compared in terms of the total sum of the damping coefficients. The effectiveness of the different distributions is then examined by performing time-history analysis of several case studies considering a nonlinear behavior both for the viscous dampers and for the structural members. The results of the nonlinear dynamic analyses are examined in terms of inter-story drifts and dampers forces. The considered case studies are five RC frames characterized by different number of stories (3, 6 and 9 stories) and also by different properties in terms of regularity in elevation. In this way it is also possible to investigate the effect of the vertical distribution of the damper properties for regular and irregular frames.

Stochastic Vibration-Based Fragility Analysis of Middle-Story RC Frames

2011 ◽  
Vol 204-210 ◽  
pp. 1235-1238
Author(s):  
Jian Zhu ◽  
Ping Tan
Keyword(s):  
Fragility Curves ◽  
Response Spectrum ◽  
Time History ◽  
Seismic Intensity ◽  
Western China ◽  
Fragility Analysis ◽  
Design Practice ◽  
Rc Frames ◽  
History Analysis ◽  
Set Up

A lot of reinforced concrete (RC) frames have being collapsed during Si Chuan Earthquake (SCE) in western China May 12th.2008, at the same time others have being injured on several levers. In recent years how to evaluate reliability and fragility of the buildings and search reasonable design practice of seismic strengthening of these buildings is urgent mission. One goal of fragility analysis is set up relation between vulnerability and seismic intensity. A set of stochastic earthquake waves compatible with the response spectrum of China seismic code selected to represent the variability in ground motion. Dynamic inelastic time history analysis was used to analyze the random sample of structures. In the end structural weak position also be pointed as valuable consultation for diagnose these buildings and fragility curves of typical middle-storey RC frames of China was obtained finally.

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