scholarly journals Dynamic increase factor in reinforced concrete frames under disproportionate collapse

2017 ◽  
Author(s):  
◽  
Joseph Ernest Kirby
Keyword(s):  
Reinforced Concrete ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Catenary Action ◽  
Sudden Loss ◽  
Dynamic Increase Factor ◽  
Concrete Frame ◽  
Disproportionate Collapse ◽  
Live Loads ◽  
Internal Forces

Under a disproportionate collapse, the sudden loss of a support causes a dynamic response that can amplify the internal forces in the surrounding members and lead to significant global damage. This study considered a two-dimensional, quarter scale, two bay, two story reinforced concrete frame with discontinuous reinforcement. In order to simulate an interior bay condition, the frame was axially restrained at the adjacent-bay beam locations. Dead weights were applied to simulate the dead and live loads expected to be present during a collapse event. To initiate the test, and to simulate the sudden loss of a load-bearing column, a kickstand was implemented. The results presented herein are from four dynamic tests under various levels of applied load. The fourth drop, with a load corresponding to 42 percent of the 1.2*DL + 0.5*LL typically specified in disproportionate collapse guidelines, resulted in a catenary action. The results show that there is a very fine tipping point at which the structure is pushed past the compressive arch and flexural range of resistance into the catenary action range (hereafter referred to as the snap-through effect). Furthermore, the results show that due to this snap-through effect, the dynamic increase factor can be as great as 2.4, significantly higher than the value specified by the aforementioned guidelines.

Seismic risk for commercial buildings in Memphis

1983 ◽  
Vol 73 (5) ◽  
pp. 1435-1450
Author(s):  
Andrzej S. Nowak ◽  
Elizabeth L. M. Rose
Keyword(s):  
Reinforced Concrete ◽  
Seismic Risk ◽  
Steel Structure ◽  
Structural Type ◽  
Commercial Buildings ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Damage Prediction ◽  
Concrete Frame

Abstract This paper deals with the evaluation of seismic risk for commercial buildings in Memphis, Tennessee. The seismicity of the area is summarized, and commercial buildings are divided into categories with regard to parameters such as number of stories, year of construction, assessed value, total floor area, and structural type. The distributions of these parameters are presented in the figures. During the study, over 15 buildings were examined on site by a team of experts to evaluate their seismic resistances. The quality of the design, materials, and construction was found to be surprisingly good, particularly in those structures built since 1900. Seismic resistance is analytically evaluated for five buildings: a four-story reinforced concrete frame; a four-story steel structure with vertical trusses; a 13-story stell frame; and two multi-story reinforced concrete frames. The loadings from four sources are considered: EI Centro and Taft earthquakes in California (1940 and 1952, respectively) and the forces specified in the 1979 UBC and 1981 BOCA codes. Ratios of load to capacity are calculated. For each building considered, the expected percentage of damage is evaluated for the two earthquakes. The damage prediction is extended to all commercial buildings in Memphis.

Experimental and Numerical Studies on the Reinforced Concrete Frames Subjected to Blast Loads

2012 ◽  
Vol 157-158 ◽  
pp. 1173-1177
Author(s):  
Li Xiao ◽  
Wen Zhong Qu ◽  
Jian Gang Wang
Keyword(s):  
Reinforced Concrete ◽  
Numerical Models ◽  
Computer Code ◽  
Economic Loss ◽  
Frame Structure ◽  
Building Structures ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Blast Response

Terrorist bombing attacks will endanger and may even destroy the target building structures, resulting in economic loss and casualties. Typical columns and floor slab systems are not designed to resist the complex blast loading. So, in recent years, the effects of blast on conventional public buildings are focused on. In this paper,a two-bay,one-story reinforced concrete frame structure which is used to model a portion of a typical reinforced concrete frame structural system is used to investigate the blast response. The experiments are conducted on two models, allowing a variation in explosives standoff and explosives charge. In each experiment,the blast pressure values are recorded and the degree of damage of the frames are studied. According to the two kinds of experiments, two numerical models are established. ALE method which considers the interaction of the explosive, the air, and the structure is applied.Structure response analyses are performed using the large deformation finite-element computer code, LS-DYNA. The numerical results are compared with the experiment results, and a good agreement is obtained. The calculating results also demonstrate that some experimental value is unreasonable.

Rehabilitation of Reinforce Concrete Frames with Reinforced Concrete Infills

2006 ◽  
Vol 324-325 ◽  
pp. 635-638
Author(s):  
Chang Sik Choi ◽  
Hye Yeon Lee
Keyword(s):  
Reinforced Concrete ◽  
Resistance Mechanism ◽  
Reinforce Concrete ◽  
Structural Performance ◽  
Concrete Frames ◽  
Initial Stiffness ◽  
Reinforced Concrete Frame ◽  
Infill Wall ◽  
Concrete Frame ◽  
Lightly Reinforced Concrete

The purpose of this study is to understand the fundamental resistance mechanism and the shear strength of the frame with the reinforced concrete infill wall by comparing analytical with experimental results. For this, one-story and one-bay four specimens were manufactured with variables; Lightly Reinforced Concrete Frame (LRCF), monolith placing Shear Wall (SW), CIP Infill Wall (CIW-1) and CIP Infill Wall reinforced with diagonal rebar (CIW-2). The addition of the RC infill wall was significantly improved the strength and the stiffness. Compared with specimen LRCF, ultimate strength and initial stiffness of infills was improved 4 and 6 times, respectively. The case of specimen CIW-2, structural performance was improved remarkably by placing a diagonal rebar.

The shearing performance of a beam-column joint in a reinforced concrete frame subjected to bidirectional loading

2019 ◽  
Vol 22 (15) ◽  
pp. 3176-3189
Author(s):  
Zhenbao Li ◽  
Yanwei Cui ◽  
Kun Song ◽  
Hua Ma ◽  
Zhenyun Tang
Keyword(s):  
Reinforced Concrete ◽  
Calculation Model ◽  
Shear Capacity ◽  
Detailed Calculation ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Shear Mechanism ◽  
Column Joint ◽  
Reinforced Concrete Frame Structures

The anti-seismic capability of beam-column joints in reinforced concrete frame structures undergoing bidirectional loading may be lower than the designed capability for unidirectional earthquake action. To date, detailed calculation methods for the shear capability and shearing performance for joints in reinforced concrete frames subjected to bidirectional loading have not been reported. In this work, the shear mechanism of the beam-column joint in a reinforced concrete frame under bidirectional loading is analyzed. The study shows that when a synthetic shear force is imposed on the joint, the oblique compression zone comes into being at the corner of the joint, and the oblique compression strut is formed in the core area of the joint, which is different from the shear mechanism of the joint under unidirectional loading. A shear capacity calculation model is established based on the strut-and-tie model. Through the testing of reinforced concrete frame joints under bidirectional monotonous loading, the combined shear and deformation in the joint are obtained, the mechanical properties in each principal plane and in the combined shear action plane are analyzed, the shearing performance of the joints in a reinforced concrete frame under bidirectional loading is defined, and the shear contributions of hoop and column reinforcement are verified. The predicted values of the shear capability in this work are in good agreement with the reported experimental results.

Determination of the Basic Force-Displacement on the Top in the Case of the Structure with Reinforced Concrete Frames P+6

2018 ◽  
Vol 20 (1) ◽  
pp. 73-80
Author(s):  
Florin Ţepeş Onea ◽  
Marian Dragomir
Keyword(s):  
Reinforced Concrete ◽  
Frame Structure ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Basic Force ◽  
Non Linear ◽  
Lateral Displacements ◽  
Force Displacement

Abstract The theme of the paper is to design the capacity of a P + 6E construction with reinforced concrete frame structure and determination of the basic force-displacement on the top. Drawing the cutting force - the displacement at the top requires a non-linear bias of the pushover type. The non-linear static calculation is used in the displacement-based design methodology, in which lateral displacements are considered the main parameter for characterizing the seismic response of the structures.

Quantifying the Reduction in Collapse Safety of Main Shock–Damaged Reinforced Concrete Frames with Infills

2017 ◽  
Vol 33 (1) ◽  
pp. 25-44 ◽  
Author(s):  
Henry V. Burton ◽  
Mayank Sharma
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Analysis ◽  
Main Shock ◽  
Limit State ◽  
Incremental Dynamic Analysis ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Frame Buildings ◽  
Story Drift

A performance-based methodology is presented to quantify the reduction in collapse safety of main shock–damaged reinforced concrete frame buildings with infills. After assessing their collapse safety in the intact state, the residual collapse capacity following main shock damage is evaluated by conducting incremental dynamic analysis to collapse using main shock–aftershock ground motion sequences. The median collapse capacity and conditional probability of collapse for the main shock–damaged building, normalized by that of the intact case are the metrics used to measure the reduction in collapse safety. Taller buildings with built-in soft and weak first stories have the highest reduction in collapse safety as a result of main shock damage. Among the engineering demand parameters recorded during the main shock analyses, story drift demands (peak transient and residual) and infill strut axial deformations have the highest correlation with the decline in collapse performance. The results of the main shock–aftershock incremental dynamic analysis to collapse are used to develop fragility functions for the limit state defined by the building being structurally unsafe to occupy.

scholarly journals Influence of Different Types of Infill Walls on the Hysteretic Performance of Reinforced Concrete Frames

Buildings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 310
Author(s):  
Fei Wang ◽  
Kaozhong Zhao ◽  
Jianwei Zhang ◽  
Kai Yan
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Bearing Capacity ◽  
Frame Structure ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Infill Walls ◽  
Concrete Frame ◽  
Hysteretic Performance ◽  
Energy Dissipation Capacity

To study the influence of masonry infill walls on the hysteretic performance of reinforced concrete frames, a cyclic experiment was conducted for three two-story and two-span reinforced concrete frame structures, including one reinforced concrete frame without infill walls and two frames with infill walls. Whether the infill walls were constructed in the frames and the type of infilled material were the main parameters of the test. The major results reveal that: the infill walls clearly changed the mechanical mechanism of the frame structure at the early stage of loading, magnified the stiffness and horizontal bearing capacity of the frame structure, and enhanced the energy dissipation capacity of the frame structure, but reduced the deformation performance of the frame structure. In the later stage of loading, the infill walls would no longer work as one with the frame gradually with the failure of the infill walls, and the above performance of the structure would approach the empty frame structure. Moreover, the initial stiffness, energy dissipation capacity, and horizontal bearing capacity of the frame with infill walls of clay hollow bricks were the highest among the three specimens. But due to the strong diagonal bracing effect, the damage to the top of the columns and beam-column joints was serious, the yield displacement was reduced significantly, and the shear failure of the top of the columns and the joints occurred prematurely, which showed poor performance of deformation and ductility. However, the frame with infill walls of relatively soft aerated lightweight concrete blocks showed better performance of deformation and ductility.

scholarly journals Time-dependent Seismic Performance Assessment of Corroded Reinforced Concrete Frames

2019 ◽  
Author(s):  
Mohammad Ghanooni-Bagha ◽  
Sajad Zarei ◽  
Hamid Reza Savoj ◽  
Mohsen Ali Shayanfar
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Concrete Compressive Strength ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Nonlinear Analyses ◽  
Seismic Performance Assessment ◽  
Concrete Frame ◽  
Capacity Curves ◽  
Severe Intensity

In this study, effects of reinforcement corrosion such as reinforcement cross section reduction, steel yield strength and concrete compressive strength reduction on RC member capacity decrease are studied. Next, a two-dimensional reinforced concrete moment resistant frame is modeled to evaluate the effects of moderate and severe intensity corrosion on moment-curvature behavior of elements and structure seismic response under nonlinear analysis. Structure capacity curves in push-over analysis and failure curves resulted from IDA for both the structure without and with corrosion are obtained and the effects of reinforcement’s corrosion on the reinforced concrete frame seismic performance are determined through comparing the results. The results revealed that in terms of amount, place and type of corrosion in the reinforced concrete frame, value of the reduction resisting moment of elements is different. Furthermore, the outcomes of nonlinear analyses showed that the capacity of structure is reduced and its seismic performance level is changed as a result of corrosion.

Behaviour of reinforced concrete frames rehabilitated with concentric steel bracing

2000 ◽  
Vol 27 (3) ◽  
pp. 433-444 ◽  
Author(s):  
H Abou-Elfath ◽  
A Ghobarah
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Simplified Approach ◽  
Concrete Frame ◽  
Rc Frames ◽  
Damage Indices ◽  
Steel Bracing ◽  
Story Building

The seismic performance of low-rise nonductile reinforced concrete (RC) buildings rehabilitated using concentric steel bracing is investigated. A three-story building was analysed using various ground motion records. The effectiveness of the steel bracing in rehabilitating the three-story building was examined. The effect of the distribution of the steel bracing along the height of the RC frames on the seismic performance of the rehabilitated building was studied. The behaviour of the nonductile RC frame members is represented using a beam-column element capable of modelling the strength softening and the effects of the axial force on the yield moment and the deformation capacities at peak strength of these members. The performance of the building is evaluated in terms of global and story drifts and damage indices. A simplified approach is proposed for selecting the proper brace distribution.Key words: reinforced concrete, frame, nonductile, rehabilitation, concentric steel brace.

Sign in / Sign up

Export Citation Format

Share Document