EFFECTS OF RANDOMLY DISTRIBUTED INFILL ON COLUMNS OF REINFORCED CONCRETE FRAMES WITH SOFT GROUND STOREY

2010 ◽  
Vol 10 (03) ◽  
pp. 555-569 ◽  
Author(s):  
SHAHRIAR QUAYYUM ◽  
ISLAM MOHAMMAD NAZMUL ◽  
MOST. MAHBUBA IASMIN ◽  
KHAN MAHMUD AMANAT
Keyword(s):  
Reinforced Concrete ◽  
Response Spectrum ◽  
Base Shear ◽  
Concrete Frames ◽  
Natural Period ◽  
Rc Frames ◽  
Axial Forces ◽  
Open Ground ◽  
Seismic Loadings ◽  
Structural Responses

Reinforced concrete (RC) frames with an open ground floor and various infill distributions have been analyzed for seismic loadings by the finite element method. The infills have been modeled by diagonal struts. Focus is placed on the effects of infill distribution on various structural responses, including (i) the lateral deflection, (ii) the column axial forces, (iii) the column bending moments, (iv) the base shear, and (v) the natural period of the frame. The equivalent static force method (ESFM) and response spectrum method (RSM) for linear structures have been applied, and the results obtained have been compared. It was found that the structural responses do not change appreciably by the ESFM analysis for random infill distributions, while they increase noticeably in the RSM analysis. This manifests the inadequacy of using the ESFM for general purposes, for which modifications were proposed in this paper for the design of RC columns. As the natural period of the RC frame converges with the code equations only for higher amounts of infill, it is necessary to incorporate the amount and distribution of infill in the dynamic analysis of RC frames.

scholarly journals Seismic Behavior of Mid-Rise Precast Reinforced Concrete Building with Effect of Joints and Supports

2019 ◽  
Vol 8 (4) ◽  
pp. 3633-3637
Keyword(s):  
Reinforced Concrete ◽  
Response Spectrum ◽  
Precast Concrete ◽  
Mode Shapes ◽  
Base Shear ◽  
Reinforced Concrete Building ◽  
Axial Forces ◽  
Building Models ◽  
Precast Buildings ◽  
Concrete Building

Precast concrete structures are widely used in construction. It consists of prefabricated elements casted in industry and connected to each other to form a homogeneous structure. Connections function is to transfer moments and axial forces. Many engineers assume precast connection as pinned, but in reality, they are semi-rigid connections that transfer forces to other members. Lack of design and detailing of connection leads to improper behaviour of the structure, which then leads to the collapse of the building. Past earthquake studies show that many precast buildings performed poorly, and the main reasons were connections. This paper mainly focuses on understanding the seismic behaviour of mid-rise i.e seven-storey precast reinforced concrete buildings with various beam-column joints i.e rigid, semi-rigid, pinned and column-base supports i.e, fixed and hinged supports. Building is modelled and analyzed using ETABS v17 software. Rotational stiffness of precast billet connection is adopted for modelling of semi-rigid beam-column connections. Response spectrum and modal analysis are carried out. Results of displacements, storey drift, storey shear, storey stiffness, base shear, time periods and first mode shapes of models are discussed. It is observed, precast reinforced concrete building models with semi rigid connection performs better than building models with pinned connections and building models with fixed supports reduces the structural response to a great extent.

scholarly journals BENEFIT FROM CHAINED MASONRY WALLS TO IMPROVE THE SEISMIC RESPONSE OF REINFORCED CONCRETE BUILDINGS

2021 ◽  
Vol 30 (2) ◽  
Author(s):  
Abdelkader Nour ◽  
Abdelkader Benanane ◽  
Humberto Varum
Keyword(s):  
Reinforced Concrete ◽  
Seismic Behavior ◽  
Lateral Displacement ◽  
Response Spectrum ◽  
Masonry Walls ◽  
Base Shear ◽  
Reinforced Concrete Buildings ◽  
Concrete Buildings ◽  
Finite Element Software ◽  
Seismic Loadings

The multiple earthquakes have proved the effect of chained masonry walls on the seismic behavior of multistoried reinforced concrete buildings. The chained masonry walls have been considered one of the types of masonry infill walls but without gaps. This participation came intending to study this effect through the modeling of several two-dimensional frames for a multistoried reinforced concrete building, taking into account the hollow brick walls, which represent the most common type in Algeria. We analyzed the proposed models using ETABS finite element software, relying on the response spectrum method and respecting the most important requirements according to the applicable Algerian Seismic Code. After analysis of the different models, the results have been compared according to the parameters of the period, base shear, lateral displacement, and stiffness. Through a critical synthesis of the results, we concluded that these walls could significantly affect the seismic behavior of this type of buildings. Moreover, the neglect of these walls in the modeling process can lead designers to have a false perception of the behavior of these buildings towards seismic loadings.    

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.

Behavior Study of High Impact Resistant Reinforced Concrete Frames Using Crack Conduction Method

2006 ◽  
Author(s):  
Navid Heidarzadeh ◽  
S. Mohammad Razavi ◽  
Nima Shamsaei
Keyword(s):  
Reinforced Concrete ◽  
Impact Loading ◽  
Failure Modes ◽  
Side Surface ◽  
High Impact ◽  
Structural Behavior ◽  
Concrete Frames ◽  
Rc Frames ◽  
Behavior Study ◽  
Falling Weight

In this study, the influence of crack conduction method on behavior of reinforced concrete (RC) frame under iterative high impact loading were experimented. To investigate the structural behavior through large deformations and progressive damage and to identify the failure modes, the falling weight and falling height were set more than the structural strength in elastic state. A comprehensive scheme which indicated influence of location of initial cracks on behavior and failure mode of structure was developed. Falling weight impact test was conducted on twenty-one laboratory scaled RC frames which were categorized in four series regard to considered scheme. Concrete volume and compressive strength, number of longitudinal and transverse rebar were constant factors in all specimens. Deformed shape and crack patterns, developed on the side surface of the RC frames, were sketched and total deflections vs. cumulative input energy of the RC girder were plotted. The results revealed the influence of crack conduction on improving the structural behavior and extending the endurance of RC frames against iterative high impact loading.

Cyclic Performance of Two-Story Ductile RC Frames With Infill Walls

2005 ◽  
Author(s):  
Yung-Hsin Yeh ◽  
Wen-I Liao
Keyword(s):  
Model Building ◽  
General Purpose ◽  
Rc Frame ◽  
Building Structures ◽  
Base Shear ◽  
Concrete Frames ◽  
Infill Wall ◽  
Infill Walls ◽  
Rc Frames ◽  
Short Beam

This paper presents the results of the experimental and analytical investigations conducted on four 0.8 scale 2-story one bay ductile reinforced concrete frames with infill nonstructural walls subjected to cyclically increasing loads. The material properties and the member sizes of beams and columns in the four RC frame specimens are identical, but with different types of infill nonstructural wall. These four frames are the pure frame, frame with short column, frame with short beam and frame with wing walls. The four RC frame specimens were designed and constructed according to the general prototype building structures in Taiwan. Test results indicate that the ductility behavior of the frames with infill wall is similar to those of the pure frame. The ultimate base shear strength of the frames with infill walls is higher than those of the pure frame. Analytical results show that the proposed simplified multi-linear beam-column element implemented in a general purpose structural analysis program can accurately simulate the cyclic responses of the RC frame specimen incorporating the elastic flexural stiffness computations suggested by the model building codes.

scholarly journals Analysis of the global second-order effects on irregular reinforced concrete structures using the natural period of vibration

2019 ◽  
Vol 12 (2) ◽  
pp. 408-428 ◽  
Author(s):  
F. F. LEITÃO ◽  
G. H. SIQUEIRA ◽  
L. C. M. VIEIRA JR. ◽  
S. J. C. ALMEIDA
Keyword(s):  
Reinforced Concrete ◽  
Bending Moment ◽  
Second Order ◽  
Order Effects ◽  
Concrete Frames ◽  
Natural Period ◽  
Asymmetric Structures ◽  
Mass Matrices ◽  
Modes Of Vibration ◽  
Second Order Effects

Abstract The χT parameter, a simplified method recently presented, allows to estimate the global second-order effects on reinforced concrete frames using the natural period of vibration. This parameter was developed based on the fact that both natural period of vibration and global second-order effects depend essentially on the stiffness and mass matrices of the structure, being thus related. In this paper, numerical analyses are conducted on nine models with different patterns of irregularity in terms of geometry in plan and stiffness. The main purpose of these analyses is to evaluate the applicability of the χT parameter in asymmetric structures as well as that can present torsional modes as the fundamental mode of vibration. In addition, different hypotheses are tested in order to verify the influence of the different modes of vibration in the structural sensitivity to global second-order effects. Results of the simplified analyses were compared to the final bending moment values obtained through a nonlinear numerical analysis considering the P-Δ effect. It is observed that the parameter χT is a promising indicator for a simplified estimation of the global second-order effects for concrete frames, especially when higher modes of vibration are taken account in the analysis.

scholarly journals Backstay Effect of Diaphragm in Tall Building

2020 ◽  
Vol 9 (3) ◽  
pp. 1578-1587
Keyword(s):  
Seismic Analysis ◽  
Response Spectrum ◽  
Retaining Wall ◽  
Tall Building ◽  
Structural Systems ◽  
Base Shear ◽  
High Rise ◽  
Structural Engineer ◽  
Structural Responses ◽  
Seismic Forces

Seismic analysis of structural systems with floor diaphragms has been a requisite in the recent past. The duty of a structural engineer is to be prudent about the behavior of every structural system adopted. Amongst the structural systems that are adopted world over, diaphragm with rigid and semi-rigid floor plate are adopted widely in the analysis. This research focuses on the backstay effect i.e. podium structural interaction with the tower area and consideration of retaining wall as increment of lateral stiffness as specified in latest tall building code IS6700:2016 for low and high rise structures. In the current study models were prepared with low to high rise storeys with rigid and flexible diaphragms considering backstay diaphragm placing tower at center and corner. The models were subjected to seismic forces; response spectrum along with the combination of the gravity loads. The structural responses like natural periods, base shear, displacement and inter storey drift were also studied.

An investigation on determining optimum wall ratio–cost relationship of shear walled reinforced concrete buildings

2020 ◽  
Vol 6 (1) ◽  
pp. 1
Author(s):  
İbrahim Hakkı Erkan ◽  
Talha Polat Doğan ◽  
Musa Hakan Arslan
Keyword(s):  
Reinforced Concrete ◽  
Response Spectrum ◽  
Construction Cost ◽  
Frame Structures ◽  
Structural Systems ◽  
Analysis Method ◽  
Base Shear ◽  
Shear Forces ◽  
Concrete Wall ◽  
Wall Structures

Reinforced concrete walls are very efficient structural elements in terms of carrying the lateral loads that are expected to affect the structures during the service of the buildings. These elements, which are not used for economic reasons in buildings designed in areas with low seismic hazard, can actually provide a significant increase in performance with a very small increase in construction cost. In this study, a total of 9 building models have been created and the relationship between optimum reinforced concrete wall ratio and cost on these buildings has been investigated. The design and analysis of the models were carried out according to the criteria specified in TSC 2018. Three different structural systems specified in TSC 2018 were used in the designed models. These structural systems used; RC frame structures, RC wall-frame structures and RC wall structures. These structures were analyzed by Response Spectrum Method which is linear analysis method and base shear forces were obtained. Then, push-over analysis, which is a nonlinear analysis method, was applied to obtain the base shear forces that the structure can actually carry. After the analysis, the quantities of materials to be used for the construction of the structural systems of the models were calculated and current manufacturing prices and rough costs were calculated. In order to compare the obtained costs with the structural performances, nonlinear shear forces and linear shear forces ratios were calculated and the over strength factors were calculated for each model. In the light of the data obtained from the studies in the literature, when the over strength factors and cost values are examined together, it is concluded that the optimum design for the conditions specified in TSC 2018 will be provided with the RC wall ratio between 0.001 - 0.0016. It is concluded that lateral load carrying capacity of construction increases up to 650% by increasing the construction cost by 17% for the designed models.

The Mexico Earthquake of September 19, 1985—Response and Design Spectra Obtained from Earthquake-Damaged Buildings

1989 ◽  
Vol 5 (1) ◽  
pp. 113-120 ◽  
Author(s):  
A. Gómez ◽  
R. Ortega ◽  
J. J. Guerrero ◽  
E. González ◽  
J. P. Paniagua ◽  
...  
Keyword(s):  
Mexico City ◽  
Shear Force ◽  
Response Spectrum ◽  
Base Shear ◽  
Natural Period ◽  
Safety Level ◽  
Design Spectrum ◽  
Design Spectra ◽  
Mexico Earthquake ◽  
High Seismicity

The resistant shear force of 13 buildings severely damaged by the 1985 Mexico City earthquake was determined by static and dynamic analyses. The results of the static analysis suggest the advisability of increasing the shear base coefficient of the 1987 Mexico City building code RDF87 from 0.4 to 0.6 in the high seismicity zones of the area. The results of the dynamic analysis show that in order to obtain the same safety level, the maximum ordinate of the design spectrum should be larger than the base shear coefficient used with the static method, leading to a 0.8 maximum ordinate for Mexico City. When the resistant shear force is plotted as a function of the natural period of each building, the response spectrum obtained is very similar to the inelastic spectrum derived from the accelerograms, considering 5% critical damping, a ductility factor of 4 and degradation in resistance from 5% to 10%. Based on these results, new design spectra are proposed for use in the high seismicity zones in Mexico City.

Simplified Approach Based on the Natural Period of Vibration for Considering Second-Order Effects on Reinforced Concrete Frames

2018 ◽  
Vol 18 (05) ◽  
pp. 1850074 ◽  
Author(s):  
Daniel G. Reis ◽  
Gustavo H. Siqueira ◽  
Luiz C. M. Vieira ◽  
Ronald D. Ziemian
Keyword(s):  
Reinforced Concrete ◽  
Amplification Factor ◽  
Flexible Structures ◽  
Second Order ◽  
Order Effects ◽  
Concrete Frames ◽  
Natural Period ◽  
Reinforced Concrete Frames ◽  
Order Analysis ◽  
Second Order Effects

Recent studies have demonstrated the existence of a relationship between a structures susceptibility to second-order effects and its natural period of vibration ([Formula: see text]) given that both these properties are fundamentally dependent on the structure stiffness and mass properties. The main advantage of the use of this characteristic is that [Formula: see text] can be obtained easily by the existing structural analysis software. In this study, different formulations are developed in order to propose an amplification factor ([Formula: see text]) to multiply first-order analysis results and satisfactorily obtain results of a second-order analysis. These formulations are based on D’Alembert’s principle, Rayleighs method, and the use of generalized coordinates to represent the dynamic displacement of flexible structures. It is observed that [Formula: see text] provides values closer to and in fact, more conservatively than, those obtained by the conventional simplified methods currently used by structural design engineers. Thus, the amplification factor [Formula: see text], which is based on the natural period of vibration, is proposed to be used as (i) an indicator of a structure susceptibility to second-order effects and (ii) an amplification factor to describe the second-order effects on reinforced concrete frames.

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