Showing papers in "Advances in Structural Engineering in 2014"

Quality Assessment of Unmanned Aerial Vehicle (UAV) Based Visual Inspection of Structures

Abstract: This paper discusses the application of Unmanned Aerial Vehicles (UAV) for visual inspection and damage detection on civil structures. The quality of photos and videos taken by using such airborne vehicles is strongly influenced by numerous parameters such as lighting conditions, distance to the object and vehicle motion induced by environmental effects. Whilst such devices feature highly sophisticated sensors and control algorithms, specifically the effects of fluctuating wind speeds and directions affect the vehicle motion. The nature of vehicle movements during photo and video acquisition in turn affect the quality of the data and hence the degree to which damages can be identified. This paper discusses the properties of such flight systems, the factors influencing their movements and the resulting photo quality. Based on the processed data logged by the high precision sensors on the UAV the influences are studied and a method is shown by which the damage assessment quality may be quantified.

Achievements and Challenges in Machine Vision-Based Inspection of Large Concrete Structures

Abstract: Large concrete structures need to be inspected in order to assess their current physical and functional state, to predict future conditions, to support investment planning and decision making, and to allocate limited maintenance and rehabilitation resources. Current procedures in condition and safety assessment of large concrete structures are performed manually leading to subjective and unreliable results, costly and time-consuming data collection, and safety issues. To address these limitations, automated machine vision-based inspection procedures have increasingly been proposed by the research community. This paper presents current achievements and open challenges in vision-based inspection of large concrete structures. First, the general concept of Building Information Modeling is introduced. Then, vision-based 3D reconstruction and as-built spatial modeling of concrete civil infrastructure are presented. Following that, the focus is set on structural member recognition as well as on concrete damage detection and assessment exemplified for concrete columns. Although some challenges are still under investigation, it can be concluded that vision-based inspection methods have significantly improved over the last 10 years, and now, as-built spatial modeling as well as damage detection and assessment of large concrete structures have the potential to be fully automated.

Responses of Masonry Infill Walls Retrofitted with CFRP, Steel Wire Mesh and Laminated Bars to Blast Loadings

Abstract: Many materials are available for retrofitting masonry infill walls to resist explosion loads. Selection of the most suitable material is essential for optimal performance and cost. In this study, a series of trials were conducted in a specially designed test setup to determine and compare the performances of 1/2-scale masonry infill walls retrofitted with carbon fibre-reinforced polymer strips, steel wire mesh and laminated steel bars, respectively, as well as an unreinforced masonry wall, subjected to blast loads. High fidelity FE models with detail modelling of brick, mortar and retrofitting materials are also developed in LS-DYNA to simulate the blast tests. The accuracy of the FE models in predicting the field blast tests is verified with the test data. The calibrated FE models are used to perform intensive numerical simulations to investigate the effectiveness of various retrofitting measures. The displacement response, failure mode, level of damage and fragmentation from both the field blasting test...

Numerical and Experimental Investigations on Seismic Response of Building Frames under Influence of Soil-Structure Interaction

Abstract: In this study, an enhanced numerical soil-structure model has been developed which treats the behaviour of soil and structure with equal rigour. The proposed numerical soil-structure model has been verified and validated by performing experimental shaking table tests. To achieve this goal, a series of experimental shaking table tests were performed on the physical fixed based (structure directly fixed on top of the shaking table) and flexible base (considering soil and structure) models under the influence of four scaled earthquake acceleration records and the results were measured. Comparing the experimental results with the numerical analysis predictions, it is noted that the numerical predictions and laboratory measurements are in a good agreement. Thus, the proposed numerical soil-structure model is a valid and qualified method of simulation with sufficient accuracy which can be employed for further numerical soil-structure interaction investigation studies. Based on the predicted and observed values ...

Performance-Based Seismic Design of RC SMF Using Target Drift and Yield Mechanism as Performance Criteria

Abstract: Reinforced concrete special moment frames (RC SMF) have been widely used as part of seismic force-resisting systems. Design methodologies and systematic procedures of RC SMF are needed which require no or little iteration after initial design in order to meet the targeted design objectives. This paper presents the first time application of the Performance-Based Plastic Design (PBPD) approach to RC SMF. The PBPD method uses pre-selected target drift and yield mechanisms as key performance objectives. These two design parameters are directly related to the degree and distribution of structural damage, respectively. Four baseline RC SMF (4, 8, 12 and 20-story) as used in the FEMA P695 were selected for this study. Those frames were redesigned by the PBPD approach. The baseline code designed frames and the PBPD frames were subjected to extensive inelastic pushover and time-history analyses. The seismic responses of the study frames met the targeted performance criteria with considerable improvement over the c...

Seismic Performance Upgrading for Underground Structures by Introducing Shear Panel Dampers

Abstract: A new method of upgrading seismic performance for underground structures is proposed in this paper. Both single-story and double-story underground subway stations are studied. Using the famous single-story Daikai Station model, by which the reliability of the numerical model is verified, seismic efficiency of Shear Panel Damper (SPD) in underground structures is proven. Then, in order to design appropriate and efficient SPDs for underground structures, strength ratio, one of the design parameters, is employed to investigate the seismic performance of structures. The recommended optimum range of strength ratio is given. Afterwards, typical double-story three-span stations with different SPDs layout forms are analyzed to figure out the optimal placement of SPDs. And some interesting conclusions are obtained, which may provide a convenient way to design SPDs in multi-story underground structures.

Control Force Characteristics of Different Control Strategies for the Wind-Excited 76-Story Benchmark Building Structure:

Abstract: In accordance with the International Association of Structural Control and Monitoring (IASCM) third generation Vibration Control Benchmark problem, two new control strategies: structural adjacent reaction wall control (STA) and mass-semi-active-damper (AMD-2), are proposed and systematically evaluated and compared with the Benchmark standard-extended active control solutions as well as with the structural interbedded (STI) control strategy. A set of innovative evaluation indices, denoting the direction and energy relations between control forces and its velocity and/or displacement, is proposed to study the phenomena behavior as well as intrinsic mechanism of active control force of each control strategy. Throughout the comparisons among different control strategies, the function of inertia mass of Active Mass Driver/Damper (AMD) system is discussed. The AMD-2 control strategy has been developed based on a comprehensive analysis of STA control strategy, and both strategies are thoroughly evaluated against...

Seismic Behavior of Recycled Aggregate Concrete Filled Steel and Glass Fiber Reinforced Plastic Tube Columns

Abstract: This paper presents the results of seismic tests on the recycled aggregate concrete filled steel tube (RCFS) and recycled aggregate concrete filled glass fiber reinforced plastic (GFRP) tube (RCFF) columns. The objective of this study is to evaluate the seismic behavior of steel/ GFRP tube in-filled recycled aggregate concrete (RAC) columns. The main parameters in the tests are the recycled coarse aggregate (RCA) replacement percentage and the tube material. The results show that both deformation and bearing capacities of RCFF and RCFS columns are greatly improved. The seismic behavior of RCFS columns is better than that of RCFF columns. Research findings also indicate that the energy dissipation capacity and the ductility slightly change with the variation of recycled coarse aggregate replacement percentage, whereas the bond-slip has little effect on the seismic behavior. Besides the experiments, a finite element method (FEM) analysis is also conducted. It is found that the seismic behavior of both RCFS ...

An Artificial Neural Network Based Method for Seismic Fragility Analysis of Highway Bridges

Abstract: Fragility functions have become widely adopted in the seismic risk assessment of highway bridges, or even a transportation network. The computational effort required for a fragility analysis of highway bridges using incremental dynamic analysis (IDA) can become excessive, far beyond the capability of modern computing systems, especially when dealing with the structural parameter uncertainty in generating the fragility functions. In this paper, an artificial neural network (ANN) based prediction scheme for the generation of analytical fragility curves for highway bridges is presented. And the extremely time-consuming process in traditional analytical fragility methodologies is replaced by properly trained ANNs. The implementation of ANNs is focused on the simulation of median value and standard deviation of IDA curves at a given intensity level. The uniform design method (UDM) is proposed for selecting the training datasets for establishing a well-trained ANN model. It is observed that the proposed procedu...

Damping of Full-Scale Stay Cable with Viscous Damper: Experiment and Analysis:

Abstract: A full-scale cable vibration mitigation experiment was conducted by means of a 215.58-meters-long stay cable attached with a pair of viscous dampers. Test results showed that the damping of the cable was greatly increased after the installation of viscous dampers. It was found that the obtained damping of the cable with viscous dampers depended on the amplitude, and the maximum damping was smaller than the maximum attainable damping. The viscous damper showed nonlinear behaviors regarding the mechanical performances, as well as the interior stiffness. Therefore, the effect of the interior stiffness of a damper on the cable damping was also studied by using an analytical formulation of the complex eigenvalue problem. An engineering approximation concerning the damping of a taut cable with a viscous damper was proposed, where the influence of the interior stiffness was taken into account. The analytical approximate formulations were further extended to nonlinear viscous damper based on the assumption of equ...

Performance-Based Optimum Design of Steel Frames by an Improved Quantum Particle Swarm Optimization:

Abstract: The main aim of this work is to present a methodology for performance-based optimum seismic design of moment resisting steel frame structures. In the present study, an improved quantum particle swarm optimization (IQPSO) metaheuristic algorithm is proposed to implement performance-based optimum design (PBOD) process. During the optimization process, QPSO and IQPSO algorithms minimize the structural weight subject to performance constraints on inter-story drift ratios based on FEMA-356 provisions at the immediate occupancy (IO), life safety (LS) and collapse prevention (CP) performance levels. Nonlinear pushover analysis is conducted to compute the necessary structural responses during the PBOD process. Two numerical examples are presented to illustrate the efficiency of the presented methodology. The numerical results demonstrate the superiority of the proposed IQPSO to the classical QPSO algorithm.

Progressive Collapse Mechanisms of Steel Frames Exposed to Fire

Abstract: OpenSees is an open-source object-oriented software framework developed at UC Berekeley. The OpenSees framework has been recently extended to deal with structural behavior under fire conditions. This paper summaries the key work done for this extension and focuses on the application of the developed OpenSees to study the fire-induced progressive collapse mechanisms of steel structures. The implicit dynamic analysis method (Newmark method) is applied and the influences of the load ratios, beam sizes and fire scenarios on the collapse behavior of frames are investigated. Single-compartment fire scenarios in the central bay and edge bay are considered, respectively. A total of four collapse mechanisms of steel frames are proposed by varying the three influencing factors. Most of the collapse of steel frames is triggered by the buckling of the heated columns. The thermal expansion of heated beams at early heating stage and their catenary action at high temperature have great influences on the collapse mechani...

Protection Effect of Railway Wind Barrier on Running Safety of Train under Cross Winds

Abstract: The wind tunnel test is conducted to measure the wind loads of a train and the wind pressure distribution above track. The dynamic responses of vehicle are calculated by using the coupling vibration method of wind-vehicle-bridge (line) systems with the aid of the self-developed software BANSYS(Bridge Analysis System) to determine the protection effect of wind barrier. Three kinds of porosities and four kinds of heights are installed on three line structural forms. The aerodynamic mechanism of wind barriers on the railway is investigated and the effects of sudden changes of vehicle wind loads are examined by measuring the aerodynamic coefficients of a single train. The quantity of wind loads' sudden change and the dynamic responses of vehicles is considered as the input index. The protection effect of wind barrier is evaluated by data envelopment analysis (DEA) when the output is the same. The results show that the wind barrier with a certain height could increase the lift-drag ratio and is more likely to ...

Sensor Placement Optimization in Structural Health Monitoring Using Cluster-in-Cluster Firefly Algorithm

Abstract: The determination of the optimal sensor placement (OSP) is a significant task that must be completed before a structural health monitoring (SHM) system is implemented on a real structure. The firefly algorithm (FA) is a recently developed nature-inspired metaheuristic algorithm for continuous optimization problems. This paper proposes a cluster-in-cluster firefly algorithm (CiCFA) for the optimum SHM sensor deployment. First, the code defining position coordinates in basic FA is replaced with a one-dimensional binary coding system, and the Euclidean distance is replaced by the Hamming distance. Then, a movement scheme for a darker firefly approaching a lighter firefly is developed. Last, a cluster-in-cluster strategy is employed to improve the convergence speed. In addition, a self-adaptive dynamic penalty function is introduced to convert the constraint imposed by the limited wireless data transmission range in the optimal wireless sensor placement (OWSP) problem to an unconstrained optimization problem....

The Effect of Lap Splice Length on the Cyclic Lateral Load Behavior of RC Members with Low-Strength Concrete and Plain Bars

Abstract: Many existing reinforced concrete buildings in developing countries located in seismic areas do not possess sufficient strength and ductility characteristics to resist the effects of severe earthquakes. Among other deficiencies, improper detailing of reinforcement and poor quality of materials are major causes of poor seismic performance. More specifically, inadequate lap splice lengths provided at floor levels on plain column longitudinal bars, particularly when concrete strength is low, is a widespread deficiency that has not been investigated in detail to date. Information on the behavior of such columns under earthquake actions is extremely important for reliable assessment of the seismic safety of many existing structures with detailing deficiencies and poor construction quality. In this study, the effect of lap splice length on the cyclic lateral load behavior of low-strength RC columns with plain longitudinal bars (14 mm diameter) was investigated experimentally. The specimens were designed to represent columns with low axial loads. The geometric ratio of the longitudinal reinforcement and the volumetric ratio of the lateral reinforcement of the columns are 1% and 0.8%, respectively. The test program included five RC columns with lap splice lengths of 25, 35, 44 and 55 times longitudinal bar diameter, as well as a reference specimen with continuous longitudinal bars. Test results clearly demonstrated that presence of 180-degree hooks at the ends of the lap splice reduces the negative influence of the inadequate lap splice length on RC member performance, even in the case of low- strength concrete. All specimens reached their flexural strengths and did not experience considerable strength degradation until large drift levels. Test observations were supported with findings of a fiber-based analytical model, which also demonstrated the influence of hooks on improving the bond slip behavior along inadequate lap splices.

Simple Method for Predicting Temperatures in Reinforced Concrete Beams Exposed to a Standard Fire

Abstract: In performance-based fire safety design, the fire performance of a structure needs to be accurately evaluated, which requires the accurate prediction of temperatures in the structure. While a finite-element or a finite-difference analysis may be carried out for this purpose, structural engineers generally prefer a simpler method. This paper therefore presents a simple, design-oriented method for predicting temperatures in RC beams under a standard fire exposure. Results from finite element heat transfer analysis are first examined to identify the key parameters that determine temperature distributions in RC beams. On the basis of this knowledge, a simple method in the form of handy formulae and diagrams is derived from regression analysis of finite element temperature data, with due consideration of the effects of beam geometry and fire exposure duration. The accuracy of the proposed method is demonstrated by comparing its predictions with temperature data from both finite element analysis and laboratory ...

Gaussian Process Machine-Learning Method for Structural Reliability Analysis

Abstract: To deal extensively with issues on implicit performance function and huge computational cost in reliability analysis, a new method for structural reliability analysis was proposed by combining the GP and importance sampling method (ISM). Firstly, a small amount of training dataset is generated by the structural analysis to train the GP. Then, the implicit performance and its derivatives are approximated by the trained GP using explicit formulations. Secondly, an iterative algorithm called as the GP-based first-order reliability method is implemented to obtain the design point. During iterations, the precision of the GP approximation in the important region, which contributes significantly to the failure probability, is improved continuously by adding the new iterative design point into the training set. Finally, an importance sampling around the design point is applied to obtain the failure probability. To assess the validity of the proposed method, five numerical examples were presented and discussed, wh...

Discrete Optimum Design of Truss Structures by an Improved Firefly Algorithm

Abstract: This paper presents an improved firefly algorithm (FA) for fast optimization of truss structures with discrete variables. The enhanced accelerated firefly algorithm (AFA) is a simple, but very effective modification of FA. In order to investigate the performance and robustness of the proposed algorithm, some benchmark (structural optimization) problems are solved and the results are compared with FA and other algorithms. The results show that in some test cases, AFA not only finds lighter structures compared to other algorithms, but also converges faster. In the rest test cases, the optimal solutions are found with very less computational effort. The study also shows that the proposed AFA remarkably improves stability of the firefly algorithm in discrete design of truss structures.

Nonlinear Response of Structures Subjected to Stochastic Excitations via Probability Density Evolution Method

Abstract: Stochastic response analysis plays an increasingly important role in assessing the performance and reliability of engineering structures subjected to disastrous dynamic loads such as earthquakes and strong winds. In the past decade, a family of probability density evolution method (PDEM) has been developed where a completely decoupled generalized density evolution equation (GDEE) is proposed. The dimension of GDEE could be arbitrary and in most cases a reduced one-dimensional equation is adequate. This provides an efficient solution for stochastic response of complex engineering structures. In the present paper, PDEM is incorporated with the efficient representation of stochastic processes to implement stochastic dynamic response analysis of multi-degree-of-freedom (MDOF) systems subjected to stochastic excitations. Stochastic dynamic responses of linear and nonlinear base-excited systems are investigated by PDEM, the pseudo-excitation method and the Monte Carlo simulations. The Sobol' sequence is employe...

Incremental dynamic analysis of highway bridges with novel shape memory alloy isolators

Abstract: Base isolators are commonly used to protect highway bridges from severe seismic damage. A novel self-centering isolator based on superelastic shape memory alloy (SMA) has been proposed to be installed between the piers and decks of highway bridges. This paper systematically evaluates the seismic performance of SMA isolators via the incremental dynamic analysis (IDA) of a prototype highway bridge with SMA isolators. The multi-span reinforced concrete highway bridge and the corresponding SMA isolators are designed according to an ad hoc displacement-based design (DBD) approach. The seismic analyses are conducted under different seismic intensity levels using the computation program DRAIN2DX. IDA results indicate that the SMA isolators can effectively protect the superstructure of the highway bridge and minimize the post-earthquake residual deformation. The properly designed highway bridges with SMA isolators are subjected to limited damage under frequent and design basis earthquakes.

A Global Artificial Fish Swarm Algorithm for Structural Damage Detection

Abstract: Structural damage detection (SDD) is an important but still challenging task in the structural health monitoring (SHM) field. Many methodologies have been developed and broad application prospect are expected. However, there are still some difficulties when they are applied to the real structures. In this study, a novel global artificial fish swarm algorithm (GAFSA) is proposed for exploring a new solution to the SDD problem in the SHM field. Firstly, the basic theory of the GAFSA is introduced. The fish swarm behaviours inside water are simulated by the following four steps: random, preying, swarming and following behaviours, respectively. The artificial fish parameters are defined, the implementing procedure of GAFSA is expressed, and the computing performance of GAFSA is evaluated and compared with the basic artificial fish swarm algorithm by three test functions. Secondly, the SDD problem is modelled as a constrained optimization problem in mathematics, an objective function on optimization problem is...

Compression Behavior of Concrete Cylinders Externally Confined by Flax Fiber Reinforced Polymer Sheets

Abstract: In this article, a bi-directional flax fiber fabric with room temperature curable epoxy was used to confine concrete cylinders. The compression performances of the confined cylinders were tested on the compressive behaviors. For comparison, unidirectional basalt fiber fabric reinforced polymer (BFRP) confined cylinders were also tested. Compared to the BFRP wet layups, the flax fiber reinforced polymer (FFRP) composite exhibits nonlinear in tension, and relatively lower tensile strength and modulus, but higher elongation. FFRP in weft direction exhibits higher strength and modulus but lower elongation than that that in warp direction. The compressive test results of confined concrete cylinders indicate that FFRPs improved the ultimate strain and stress of the confined cylinders, remarkably. The coefficients of confinement of FFRP on the ultimate compression stress are slightly higher than that of BFRP. The confined cylinders with FFRP showed much higher ultimate axial strain than those with BFRP.

A Simplified Approach for Predicting Bridge Pier Responses Subjected to Barge Impact Loading

Abstract: Bridge piers are often designed to resist barge impact loads according to empirical equations given in various design codes based primarily on equivalent static analyses. Although these analyses can give useful guidance in design practice, they neglect dynamic effects which can have significant influence on barge-bridge structure interactions. It is necessary to develop an efficient and accurate method that takes into consideration of dynamic effect, material nonlinearity and structural damage in predicting impact loads and structural responses. In this study, empirical equations based on intensive numerical simulation results proposed in a previous study are used to estimate dynamic impact loads on bridge piers. The bridge structure is simplified as a nonlinear single degree of freedom system to calculate its dynamic response. As compared to detailed finite element simulation, this simplified approach is straightforward and gives reasonably accurate prediction of bridge responses. It can be used in the p...

Crack Assessment in Frame Structures Using Modal Data and Unified Particle Swarm Optimization Technique

Abstract: The present paper deals with the application of unified particle swarm optimization (UPSO) technique for solving crack assessment problems in frame like structures. UPSO is a scheme for improving performance of standard particle swarm optimization (SPSO) by harnessing its exploration and exploitation ability simultaneously. The objective function formulated for crack assessment purpose uses the changes in natural frequencies and mode shapes as the damage indicators. The efficiency of present crack assessment algorithm is demonstrated by conducting several studies. First, a numerical study conducted among several PSO variants, such as global best SPSO, local best SPSO, PSO with constriction factor, PSO with time varying acceleration coefficient and UPSO for accessing their performance in solving inverse problem for crack assessment. Secondly, the performance of UPSO based algorithm is validated with experimental results. Finally, numerical studies are conducted to investigate the performance of UPSO based ...

Entire-Process Simulation of Earthquake-Induced Collapse of a Mockup Cable-Stayed Bridge by Vector Form Intrinsic Finite Element (VFIFE) Method:

Abstract: It is important to simulate the entire-process collapse of earthquake excited cable-stayed bridge in order to assure the damage extent under strong earthquakes and to optimize the anti-collapse seismic measures. The newly developed vector form intrinsic finite element (VFIFE) method is capable of computing large deformation, large displacement, collision, and fractures that would happen in the structural collapse. Therefore, it has the potential to simulate the entire-process collapse of earthquake excited structures. For the cable-stayed bridges, the axial forces change significantly during the earthquake excitation. The interaction between the axial forces and bending moments should be taken into account. In order to address this issue, this paper first presents the formulation for integration of VFIFE method and fiber beam-column element model. A bilinear elastic-plastic constitutive damage model is proposed for the mechanical behavior of the fiber and element. The collapse analysis of a 2D mockup brid...

Experimental study on seismic behavior of 460MPa high strength steel box-section columns

Abstract: In order to study the seismic behavior of 460MPa high strength steel (HSS) box-section columns, five specimens with equal-width box-section were examined under constant axial load and cyclic horizontal load simultaneously. The axial load ratio and width-to-thickness ratio were designed as major parameters in this investigation. Failure mode, hysteretic curve, energy dissipation capacity and ductility were analyzed and compared. The experimental results showed that local buckling initiated at flange and followed by web. Under the same axial load ratio, as width-to-thickness ratio increased, local buckling occurred at a lower displacement level and the displacement levels at both peak load and failure load decreased. On the other hand, with the increase of width-to-thickness ratio, the range of local buckling wave became smaller, and the position of buckling center became closer to fixed end. It is also evidenced that the full extent of hysteric curve, energy dissipation capacity, ductility of specimens and...

Structural Strengthening of Concrete with Fiber Reinforced Cementitious Matrix (FRCM) at Ambient and Elevated Temperature — Recent Investigations in Switzerland:

Abstract: This paper presents recent experimental investigations on structural strengthening by means of (Carbon) Fiber Reinforced Cementitious Matrix (FRCM) in Switzerland. A first test series deals with full-scale reinforced concrete slabs strengthened with one or two composite reinforcement meshes embedded in a shotcrete layer. Static load tests up to failure show the efficiency of the strengthening in terms of increased yield and ultimate load compared to the reference specimen. Due to the initially necessary straightening of the textile, the contribution at lower deflection levels is limited. Only with advanced cracking and crack opening, the mesh develops its full contribution. Ultimate load is reached after a prompt relative slip of the mesh in the shotcrete. In the post-peak domain, failure by concrete crushing was observed. To study the residual tensile strength of the carbon reinforcement after exposure to high temperatures, various tensile tests on small rovings previously cut out of a composite mesh wer...

Performance Evaluation of Semi Precast Concrete Beam-Column Connections with U-Shaped Strands

Abstract: In this study, a new precast concrete (PC) beam-column joint of moment resisting frame applicable for moderate seismic regions is proposed. A semi PC beam-column connection with U-shaped strands is developed in an attempt to improve workability and provide effective stress transfer mechanism at the joint. The structural system consists of PC beams with U-shaped strands, PC columns, PC slabs, and topping concrete. A series of three interior and three exterior semi PC joint specimens was tested to investigate the structural behavior of the system subjected to the lateral cyclic load. Key test variables are the number of strands placed in the PC beam and the presence or absence of the transverse reinforcements at the connection. The experiment and performance evaluation of the system were conducted in accordance with ACI T1.1-01 (2001). According to the test results, the proposed structural system with transverse reinforcements at the joint is sufficient to use in moderate seismic regions.

Seismic Risk Analysis of Steel-MRFs by Means of Fragility Curves in High Seismic Zones

Abstract: In this study a steel moment resisting frame in a high seismic prone area in Iran has been remodeled based on different versions of Iranian Seismic Code (Standard No 2800 1988, 1999, 2005) to estimate the seismic fragility and mean annual loss for the modeled buildings At the first stage a probabilistic seismic hazard analysis (PSHA) has been performed to extract hazard curve in CRISIS platform (Akkar and Bommer 2007) earthquake prediction model for the Middle East has been used in the hazard analysis In the next stage, hundreds of nonlinear incremental dynamic analyses by means of lumped-parameter based structural models have been simulated and performed to extract the fragility curves by using OpenSees Consequently by combining the hazard curves, judgmental event trees and seismic fragility curves for the extensive damage mode (EDM), the required annual loss curves are extracted

Modelling of Steel-Concrete Composite Structures in Fire Using OpenSees

Abstract: This paper presents the extension of the structural analysis software framework OpenSees for modeling steel framed composite structures subjected to fire including the development of a geometrically nonlinear shell element. The new shell element is formed by a combination of membrane elements and Mindlin plate bending elements using a general total Lagrangian formulation. The MITC technique (Mixed Interpolation of Tensorial Components) is applied to alleviate shear locking problems and the addition of drilling degrees of freedom is included. A new thermal load class was created to define the temperature distribution through the thickness of the shell section. The two-dimensional OpenSees material, DruckerPrager, was modified to model the concrete in the composite deck slab at elevated temperature with temperature-dependent material properties according to the Eurocode 2. A three-dimensional finite element model of a composite structure was built in OpenSees, consisting of a flat reinforced concrete slab m...