The Experts below are selected from a list of 2958 Experts worldwide ranked by ideXlab platform
Khalid M Mosalam - One of the best experts on this subject based on the ideXlab platform.
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modeling progressive collapse in reinforced concrete buildings using direct element removal
Earthquake Engineering & Structural Dynamics, 2009Co-Authors: Mohamed Talaat, Khalid M MosalamAbstract:This paper presents a novel analytical formulation of an element removal algorithm based on dynamic equilibrium and the resulting transient change in system kinematics, by applying imposed accelerations instead of external forces at a node where an element was once connected. The algorithm is implemented into an open-source finite element code, numerically tested using a benchmark structural system with simplified element removal criteria, and able to capture the effect of uncertainty in member capacity. Realistic element removal criteria are introduced for mode-dependent gravity load collapse of seismically deficient and retrofitted reinforced concrete (RC) columns and unreinforced masonry (URM) Infill Walls. Two applications are conducted using structural systems of RC frames with URM Infill Walls. The first is a probabilistic study of a one-story model subjected to an ensemble of 14 ground motion recordings from similar neighboring sites during an earthquake event. The study produces empirical probability curves for partial and complete collapse conditioned on different hazard levels, and concludes that the intra-event variability is a major source of uncertainty affecting the outcome of progressive collapse simulations. The second application is a deterministic sensitivity study of progressive collapse response in a five-story structural model to uncertainty in live load, stiffness, damping, and seismic hazard level, subjected to one ground motion record. The analysis identifies the time at incipient collapse as an adequate sensitivity measure, and the uncertainty in ground motion intensity as the most important, followed by the stiffness of the URM Infill Wall. Copyright © 2009 John Wiley & Sons, Ltd.
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shake table experiment on reinforced concrete structure containing masonry Infill Wall
Earthquake Engineering & Structural Dynamics, 2006Co-Authors: Alidad Hashemi, Khalid M MosalamAbstract:A hypothetical 5-storey prototype structure with reinforced concrete (RC) frame and unreinforced masonry (URM) Wall is considered. The paper focuses on a shake-table experiment conducted on a substructure of this prototype consisting of the middle bays of its first storey. A test structure is constructed to represent the selected substructure and the relationship between demand parameters of the test structure and those of the prototype structure is established using computational modelling. The dynamic properties of the test structure are determined using a number of preliminary tests before performing the shake-table experiments. Based on these tests and results obtained from computational modelling of the test structure, the test ground motions and the sequence of shakings are determined. The results of the shake-table tests in terms of the global and local responses and the effects of the URM Infill Wall on the structural behaviour and the dynamic properties of the RC test structure are presented. Finally, the test results are compared to analytical ones obtained from further computational modelling of the test structure subjected to the measured shake-table accelerations. Copyright © 2006 John Wiley & Sons, Ltd.
Amir Ayazi - One of the best experts on this subject based on the ideXlab platform.
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concrete stiffened steel plate shear Walls with an unstiffened opening
Structures, 2017Co-Authors: Soheil Shafaei, Farhang Farahbod, Amir AyaziAbstract:Abstract In this study, nonlinear behavior of concrete stiffened steel plate shear Wall (CSPSW) with an opening is investigated. The study is divided into two separate parts in order to understand the effect of an unstiffened opening—locations and sizes. In phase one: four square opening sizes—small, medium, large, and very large—are selected to study the location of the opening. When the size of square opening is fixed, the location is changed over the Infill Wall. The pattern is also repeated with a new square size. In phase two: shear Walls with a centrally located circular opening are considered and the opening ratio varies from 10% to 65%. In the study, the degradations of seismic factors —the initial stiffness, the ultimate shear strength, the ductility ratio, and the energy absorption— in terms of opening ratio are calculated. According to obtained results, the behavior of CSPSWs with an opening is utterly different from corresponding SPSWs. Initial elastic stiffness of CSPSWs with an opening is independent of the opening location and ultimate shear strength is slightly affected by location. Moreover, a linear degradation in the initial elastic stiffness and the ultimate shear strength of the Infill composite Wall is observed due to increasing the opening ratio.
Soheil Shafaei - One of the best experts on this subject based on the ideXlab platform.
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steel modules of composite plate shear Walls behavior stability and design
Thin-walled Structures, 2019Co-Authors: Amit H Varma, Soheil Shafaei, Ron KlemencicAbstract:Abstract Concrete-filled composite plate shear Walls (CPSW) consist of a concrete (Infill) Wall sandwiched between two steel plates that are connected to each other using ties and anchored to the concrete Infill using these embedded ties or shear connectors. Steel modules consisting of plates, ties and shear connectors are prefabricated in the shop, transported to the field, and assembled first. The erected modules serve as falsework for construction activities and stay-in-place formwork for concrete casting. This is a primary advantage and appeal of this system. However, there is a lack of knowledge regarding the structural behavior of empty steel modules (before and during concrete casting). This paper presents the results of analytical, numerical, and experimental investigations conducted to evaluate: (i) the structural behavior of empty steel modules under their own self-weight, (ii) the stability and axial load capacity of steel modules for construction loads and activities, and (iii) the effects of concrete casting (hydrostatic pressure) in terms of the deflections and stresses induced in the steel plates. The results indicate that the effective shear stiffness of the empty modules governs their structural behavior as well as their stability. The effective shear stiffness can be estimated using the finite element method (verified using test results), or conservatively using mechanics-based equations presented in this paper. The effective shear stiffness is governed by plate slenderness, defined by the tie spacing and plate thickness, and the relative flexural rigidity of the steel plates and the connecting ties. These parameters can be designed to limit the flexibility and the critical buckling stress of the empty modules. The paper also provides equations for calculating the out-of-plane displacement and stresses induced in the steel plates by the concrete casting hydostatic pressure.
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concrete stiffened steel plate shear Walls with an unstiffened opening
Structures, 2017Co-Authors: Soheil Shafaei, Farhang Farahbod, Amir AyaziAbstract:Abstract In this study, nonlinear behavior of concrete stiffened steel plate shear Wall (CSPSW) with an opening is investigated. The study is divided into two separate parts in order to understand the effect of an unstiffened opening—locations and sizes. In phase one: four square opening sizes—small, medium, large, and very large—are selected to study the location of the opening. When the size of square opening is fixed, the location is changed over the Infill Wall. The pattern is also repeated with a new square size. In phase two: shear Walls with a centrally located circular opening are considered and the opening ratio varies from 10% to 65%. In the study, the degradations of seismic factors —the initial stiffness, the ultimate shear strength, the ductility ratio, and the energy absorption— in terms of opening ratio are calculated. According to obtained results, the behavior of CSPSWs with an opening is utterly different from corresponding SPSWs. Initial elastic stiffness of CSPSWs with an opening is independent of the opening location and ultimate shear strength is slightly affected by location. Moreover, a linear degradation in the initial elastic stiffness and the ultimate shear strength of the Infill composite Wall is observed due to increasing the opening ratio.
Liborio Cavaleri - One of the best experts on this subject based on the ideXlab platform.
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ip oop interaction in urm Infilled frame structures a new macro modelling proposal
Engineering Structures, 2020Co-Authors: Bharat Pradhan, Liborio CavaleriAbstract:Abstract Reinforced concrete frame structures with unreinforced masonry (URM) Infills represent a common construction practice all over the world. To correctly assess the seismic performance of these structures, prediction of the behaviour of masonry Infills under in-plane (IP) and out-of-plane (OOP) loading, as well as their interaction, is of primary importance. Different approaches are available in the literature with different levels of approximation for assessment of the IP-OOP Infill response, showing increasing interest in this field. In this context, this paper presents a new macro-element model which can simulate the behaviour of URM Infill Walls under seismic IP and OOP actions. The model is the evolution of an approach based on a 4-strut configuration characterized by one horizontal strut, one vertical strut and two diagonal struts representing the Infill Wall. The struts are modelled by fibre-section beam-column elements and their compressive behaviour is defined by empirical strength and strain parameters. The paper also presents some equations to obtain the empirical parameters mentioned, based on the actual mechanical properties of Infill Walls. In the paper, the validation of the proposed model with the experimental results available in the literature is discussed. Further, the improved capacity to simulate the arching mechanism in Infill Walls under OOP loads and the better reliability in capturing the interaction between the IP and OOP behaviours are described.
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fundamental period of Infilled reinforced concrete frame structures
Structure and Infrastructure Engineering, 2017Co-Authors: Panagiotis G Asteris, Constantinos C Repapis, Emmanouela Repapi, Liborio CavaleriAbstract:AbstractThe fundamental period of vibration appears to be one of the most critical parameters for the seismic design and assessment of structures. In the present paper, the results of a large-scale analytical investigation on the parameters that affect the fundamental period of reinforced concrete structures are presented. The influence of the number of storeys, the number of spans, the span length, the Infill Wall panel stiffness and the percentage of openings within the Infill panel on the fundamental period of Infilled RC frames was investigated. Based on these results, a regression analysis is applied in order to propose a new empirical equation for the estimation of the fundamental period. The derived equation is shown to have better predictive power compared with equations available in the literature.
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parameters affecting the fundamental period of Infilled rc frame structures
Earthquakes and Structures, 2015Co-Authors: Panagiotis G Asteris, Constantinos C Repapis, Athanasios K Tsaris, Fabio Di Trapani, Liborio CavaleriAbstract:Despite the fact that the fundamental period appears to be one of the most critical parameters for the seismic design of structures according to the modal superposition method, the so far available in the literature proposals for its estimation are often conflicting with each other making their use uncertain. Furthermore, the majority of these proposals do not take into account the presence of Infills Walls into the structure despite the fact that Infill Walls increase the stiffness and mass of structure leading to significant changes in the fundamental period numerical value. Toward this end, this paper presents a detailed and in-depth analytical investigation on the parameters that affect the fundamental period of reinforce concrete structure. The calculated values of the fundamental period are compared against those obtained from the seismic code and equations proposed by various researchers in the literature. From the analysis of the results it has been found that the number of storeys, the span length, the stiffness of the Infill Wall panels, the location of the soft storeys and the soil type are crucial parameters that influence the fundamental period of RC buildings.
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on the fundamental period of Infilled rc frame buildings
Structural Engineering and Mechanics, 2015Co-Authors: Panagiotis G Asteris, Liborio Cavaleri, Constantinos C Repapis, Vasilis Sarhosis, Adamantia AthanasopoulouAbstract:This paper investigates the fundamental period of vibration of RC buildings by means of finite element macro-modelling and modal eigenvalue analysis. As a base study, a number of 14-storey RC buildings have been considered \"according to code designed\" and \"according to code non-designed\". Several parameters have been studied including the number of spans; the span length in the direction of motion; the stiffness of the Infills; the percentage openings of the Infills and; the location of the soft storeys. The computed values of the fundamental period are compared against those obtained from seismic code and equations proposed by various researchers in the literature. From the analysis of the results it has been found that the span length, the stiffness of the Infill Wall panels and the location of the soft storeys are crucial parameters influencing the fundamental period of RC buildings.
Mohamed Talaat - One of the best experts on this subject based on the ideXlab platform.
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modeling progressive collapse in reinforced concrete buildings using direct element removal
Earthquake Engineering & Structural Dynamics, 2009Co-Authors: Mohamed Talaat, Khalid M MosalamAbstract:This paper presents a novel analytical formulation of an element removal algorithm based on dynamic equilibrium and the resulting transient change in system kinematics, by applying imposed accelerations instead of external forces at a node where an element was once connected. The algorithm is implemented into an open-source finite element code, numerically tested using a benchmark structural system with simplified element removal criteria, and able to capture the effect of uncertainty in member capacity. Realistic element removal criteria are introduced for mode-dependent gravity load collapse of seismically deficient and retrofitted reinforced concrete (RC) columns and unreinforced masonry (URM) Infill Walls. Two applications are conducted using structural systems of RC frames with URM Infill Walls. The first is a probabilistic study of a one-story model subjected to an ensemble of 14 ground motion recordings from similar neighboring sites during an earthquake event. The study produces empirical probability curves for partial and complete collapse conditioned on different hazard levels, and concludes that the intra-event variability is a major source of uncertainty affecting the outcome of progressive collapse simulations. The second application is a deterministic sensitivity study of progressive collapse response in a five-story structural model to uncertainty in live load, stiffness, damping, and seismic hazard level, subjected to one ground motion record. The analysis identifies the time at incipient collapse as an adequate sensitivity measure, and the uncertainty in ground motion intensity as the most important, followed by the stiffness of the URM Infill Wall. Copyright © 2009 John Wiley & Sons, Ltd.