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concrete-structure
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Reduction of Residual Displacement of Concrete Structures by use of High Strength Rebars
, M.Sc. Thesis Sharif University of Technology ; Khalu, Alireza (Supervisor)
Abstract
Reinforced concrete bridge columns located in regions of high seismicity are designed with large ductility capacity for adequate protection against collapse. This type of design tends to result in large permanent displacements. To maximize post-event operability and to minimize repair costs, new design strategies to reduce these residual displacements are necessary. Even though seismic codes ensure life safety for bridges, large residual displacement after severe earthquake may make the bridge useless. For example, after 1995 Hyogo-ken Nanbu earthquake (Japan), more than 100 reinforced concrete bridge columns experienced a tilt angle of more than 1 degree (1.75% drift). These columns had to...
Life Cycle Cost Analysis and Comparison Of Concrete Structures with and Without Shear Walls by Endurance Time Method
, M.Sc. Thesis Sharif University of Technology ; Esmaeilpour Estekanchi, Homayun (Supervisor)
Abstract
The actual value of structures should not be evaluated only based on initial cost, because failure cost and economical losses due to corrosion and natural hazards can be catastrophic. When a long life Performance of a structure is expected, life cycle cost analysis is the best way to assess and compare economic value of different design choices. The main purpose of this work is investigating the effect of shear walls in limit state cost and total cost . Results demonstrate that shear walls can reduce limit state cost up to 70 percent . Furthermore the influence of increasing thickness of shear walls and effect of reducing dead loads in total life cycle cost is discussed. It is shown that...
A model for the evolution of concrete deterioration due to reinforcement corrosion
, Article Mathematical and Computer Modelling ; Volume 52, Issue 9-10 , November , 2010 , Pages 1403-1422 ; 08957177 (ISSN) ; Kiani, K ; Hashemian, A ; Sharif University of Technology
2010
Abstract
One of the most crucial factors affecting the service life of reinforced concrete (RC) structures attacked by aggressive ions is reinforcement corrosion. As the steel corrosion progresses, crack propagation in concrete medium endangers the serviceability and the strength of RC structural members. In this study, a nonlinear mathematical model for determining the displacement and stress fields in RC structures subjected to reinforcement corrosion is introduced. For corrosion products, a nonlinear stress-strain relation which has been previously confirmed by experimental data is incorporated in the present analysis. In formulation of the governing equations for steel-rust-concrete composite,...
Influence of diaphragm opening on seismic response of rectangular RC buildings with end shear walls
, Article Scientia Iranica ; Volume 23, Issue 4 , 2016 , Pages 1689-1698 ; 10263098 (ISSN) ; Masoomi, H ; Nozhati, S ; Mohamadi Dehcheshmeh, M ; Sharif University of Technology
Sharif University of Technology
2016
Abstract
Routinely, behavior of floor diaphragms is assumed completely rigid in their plane, which leads to erroneous results in analysis and design of some particular buildings. In this study, 4-story RC buildings, with end shear walls and plan aspect ratio of 3, are considered in order to investigate the influence of diaphragm openings on their seismic response. It is concluded that although in-plane floor flexibility has enormous effects on pre-yielding part of pushover curve, it has no influence on post-yielding part of that. Furthermore, the opening beside shear walls has crucial impact on response of building. Hence, it would be better off avoiding opening near the shear walls; if not, the...
Investigating the Location of Damping Center to Reduce the Torsional Response of Asymmetric Concrete Structures Under Near-Field Earthquakes
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayaz (Supervisor)
Abstract
Researches carried out on the damages imparted to the building structures under severe earthquakes have shown the importance of asymmetry effects of the buildings on the level of these damages. In these cases, the structures enter into the nonlinear state of their behavior and the structural elements, as well as nonstructural ones undergo large deformations. Additional damping systems have been proposed in many studies to avoid enforcing such large forces on the structures. One example of these systems is viscous fluid damper. The effectiveness of this type of dampers in reduction of the forces has been shown in many previous works. In this research we look for a damping eccentricity which...
On the modal incremental dynamic analysis of reinforced concrete structures, using a trilinear idealization model
, Article Engineering Structures ; Volume 33, Issue 4 , 2011 , Pages 1117-1122 ; 01410296 (ISSN) ; Mofid, M ; Sharif University of Technology
Abstract
In order to estimate the seismic demands at the performance level, the inelastic behavior of concrete structures should be considered. Incremental dynamic analysis (IDA) based on a nonlinear response time history analysis (NL-RHA) is considered to be the most accurate method in seismic demand calculations. However, modal incremental dynamic analysis (MIDA), based on the equivalent single-degree-of-freedom (SDF) oscillator, is also often used in studying structural engineering performances. As the MIDA method has usually not been applied to reinforced concrete (RC) structures, in this study an attempt is made to investigate the performances of RC frames and to compare the results obtained...
Evaluation of the Friction Dampers Effect on Seismic Retrofit of Non-ductile Concrete Structures
, M.Sc. Thesis Sharif University of Technology ; Golafshani, Ali Akbar (Supervisor)
Abstract
Iran plateau is situated over the Alpide-Himalaya earthquake belt. Tectonic studies indicate that this plateau has a very high density of active and recent faults; as a result, Iran is at risk of damaging earthquakes. Experience of past severe earthquakes shows previous designed structures do not have enough strength instead of real earthquake forces, therefore vulnerability study of existing structures and give a technical and economical retrofitting plan of them is required. Conventional methods of seismic rehabilitation for example using concrete shear walls or steel braces are not suitable for some buildings. Nowadays, passive control systems have been successfully used for reducing the...
Improvement in Reinforced Concrete Beam-Column Connections Behavior using Steel Plates
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Ali Reza (Supervisor)
Abstract
Performance of reinforced concrete frames is highly dependent on detailing of the joint connections between its members, such as beams and columns. To have a good structural behavior, joints must show ductile behavior and designed based on the philosophy of strong column-weak beam. In the case of sever lacking ductility, strength or even rigidity of the connections, or having a weak column-strong beam, in the existing structures, there is a need for seismic upgrading of the connection. There are several ways for seismic upgrading of this type of connections.In this research, using steel plates for seismic upgrading of Concrete Beam-Column connections subjected to axial and cyclic loads has...
Investigating The Seismic Performance of R/C Buildings Equipped With Shape Memory Alloy Braces
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
Abstract
Shape memory alloys (SMAs) are metallic materials that have unique properties, including shape memory effects, superelastic effects, and high damping characteristics. Recovery of large deformation and capability of energy dissipation during mechanical loading-unloading cycles are special properties of superelastic effect of shape memory alloys. Due to these distinctive macroscopic behaviors, not present in most traditional materials, SMAs are the basis for innovative applications like devices for protecting buildings from structural vibrations. This paper presents a numerical investigation aimed at evaluating the improvements achievable through devices for passive seismic protection of...
Nonlinear Analysis of 3D Irregular concrete Structures by Endurance Time Method
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Pourestekanchi, Homayun (Supervisor)
Abstract
The structure performances during past earthquakes indicate the importance of predicting behaviors of irregular structures under earthquakes. If the irregularity exceeds an expected limit, a seismic analysis should be carried out by a dynamic analysis method. The Endurance Time (ET) is a time-history method, base on dynamic analysis for seismic analyzing and designing the structures, in which structures are subjected to intensifying accelerogram functions and their Endurance Time is measured. One of the most applicable methods for RCF analysis is the Concentrated Hinge Model which is used in this research too. The needed parameters for modeling plasticity in concentrated hinge are achieved...
Identifying and Ranking Factors Affecting High Rise Concrete Construction Productivity (Study Current Situation and Strategies to Improve productivity)
,
M.Sc. Thesis
Sharif University of Technology
;
Mortaheb, Mohammad Mahdi
(Supervisor)
Abstract
The current global economy challenges and the importance of maintaining a sustainable development strategy has increasingly bolded the importance of construction productivity measures. This research describes the results of a running research that is to find the most critical factors affecting the productivity of high rise concrete building projects in developing countries. To achieve that, we have conducted Delphi method in two phases. In the first phase we had a brainstorming program with construction experts from owner organizations, construction contractors and designing engineers to identify factors that have influenced productivity in recent concrete building construction projects.50...
Influence of Floor Diaphragm on Seismic Response of RC Structures
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
Modeling is one of the most important steps in analysis and design of structures. Most of the time behavior of floor diaphragms is assumed completely rigid in their plane in order to simplicity in practical design. Although this assumption leads to acceptable results in analysis and design of conventional buildings, erroneous results may assess in some particular buildings—for instance narrow buildings with stiff end walls. Accordingly, behavior of these buildings in future earthquakes opposes those were predicted in design phase, and they are so vulnerable since in-plane deflection of floor diaphragms are striking which cannot be ignored. This thesis investigates the significance of...
Investigation of the Effect of Chlorine ion Concentration on Corrosion of Steel Reinforcement in Concrete
, M.Sc. Thesis Sharif University of Technology ; Afshar, Abdollah (Supervisor)
Abstract
Today, in our beloved country of Iran and other parts of the world, reinforced concrete structures are used in large industrial projects, in some cases we see their very early failure even before the time of operation. This issue in the southern coasts of the country due to special weather conditions (humidity and high temperature) and the existence of the offensive ions such as chlorine and sulfate in seawater are more important and we always face with severe corrosion of reinforcement and reduced service life of concrete structures in these areas. Despite this, little research has been done on the reliability of concrete facilities in the vicinity of the Caspian Sea in the north of the...
A comprehensive investigation into the effect of aging and coarse aggregate size and volume on mechanical properties of self-compacting concrete
, Article Materials and Design ; Vol. 59, issue , 2014 , pp. 199-210 ; ISSN: 10263098 ; Beygi, M. H. A ; Kazemi, M. T ; Vaseghi Amiri, J ; Rahmani, E ; Rabbanifar, S ; Eslami, M ; Sharif University of Technology
Abstract
The popularity of self-compacting concrete (SCC), as an innovative construction materials in concrete industry, has increased all over the world in recent decades. SCC offers a safer construction process and durable concrete structure due to its typical fresh concrete behavior which is achieved by SCC's significantly different mixture composition. This modification of mix composition may have significant effect on the hardened mechanical properties of SCC as compared to normal vibrated concrete (NVC). Therefore, it is necessary to know whether the use of all rules and relations that have been formulated for NVC in current design codes based on years of experience are also valid for SCC....
Behavior of reinforced concrete beams post-tensioned in the critical shear region
, Article Engineering Structures ; Volume 29, Issue 7 , 2007 , Pages 1465-1474 ; 01410296 (ISSN) ; Sezen, H ; Khaloo, A. R ; Sharif University of Technology
2007
Abstract
A new shear strengthening method involving post-tensioning of the critical shear region of reinforced concrete beams is investigated. Thirty-one experiments were carried out using 24 specimens. Theoretical load-deflection relations are obtained from moment-curvature analysis using fiber cross sections and taking into consideration the effects of different concrete confinements along the beam length. A theoretical shear strength model that includes three shear resisting components in the critical shear region of the strengthened beams is provided. Experimental results from beams with and without shear strengthening are compared with calculated load-deflection relations and predicted shear...
Behavior study of high impact resistant reinforced concrete frames using crack conduction method
, Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) ; Razavi, S. M ; Shamsaei, N ; Sharif University of Technology
American Society of Mechanical Engineers
2006
Abstract
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...
Introducing a response-based duration metric and its correlation with structural damages
, Article Bulletin of Earthquake Engineering ; Volume 17, Issue 11 , 2019 , Pages 5987-6008 ; 1570761X (ISSN) ; Harati, M ; Ashoori Barmchi, M ; Estekanchi, H. E ; Sharif University of Technology
Springer Netherlands
2019
Abstract
This study proposes a response-based parameter for strong motion duration which is computed for structures and is the total time they are nonlinear during an earthquake. Correlation between structural response and duration for structures, subjected to a set of spectrum matched ground motions, is employed to examine the efficiency of the proposed method. The spectral matching procedure ensures that the influence of amplitude and frequency content of motions on structural response variability is significantly removed. Four concrete building type systems are studied and correlation coefficients of structural response with the proposed duration definition are examined. Comparison of the proposed...
Performance Based Seismic Assessment of Concrete Dual Structures using Endurance Time Method
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Pourestekanchi, Homayun (Supervisor)
Abstract
The expansion of new analytical methods along with evolving computational tools has accelerated the recognition of obscured nonlinear behavior of structures. In this process, the innovative Endurance Time method is a great step which presents a comprehensive assessment of structural behavior with less computational cost. The accuracy of this method among the unpredictable nature of earthquake engineering, as well as its fastness and simplicity, has attracted the attention of researchers. This research is part of a project on introducing and assessing the capacities and restrictions of the Endurance Time method, which investigates its usage in analyzing performance of concrete structures with...
Investigating the Effect of Reinforced Concrete Wall Positioning, with Irregular Plans
, M.Sc. Thesis Sharif University of Technology ; Mofid, Masoud (Supervisor)
Abstract
Previously, numerous studies were carried out on the shear walls and important information are available in various fields, including wall design with various sections, wall design in areas with high seismicity risk, issues related to the reinforcement of boundary element and etc. In the design codes of reinforced concrete structures in the field of seismic design, some criteria for reinforcement of boundary element in the walls were conducted, but these codes do not answer to designers to arrange the wall with or without eccentricity with respect to column or the effect of separation of wall from the column. Due to the fact that we have a powerful software such as ETABS, design of shear...
The Nonlinear Analysis of the Behavior of Precast Concrete Structures Under Seismic Loads and Obtaining the Base Shear Using the Performance Based Design
,
M.Sc. Thesis
Sharif University of Technology
;
Khaloo, Alireza
(Supervisor)
Abstract
Studies have shown that by reducing the stiffness of structures the seismic load imposed on them is reduced. In this research the effect of two different precast connections on the seismic response of precast concrete structures with shear walls during earthquakes was studied. The connections were vertical connections and were used to connect the two halves of the shear walls together. The results were compared with that of a wet connection. In this research 46 different structures were analyzed. The buildings were 9, 6 and 3 stories. In order to obtain the best seismic behavior different combinations of steel were considered among the connections. The seismic behavior of the structures were...