Showing papers in "Advances in Structural Engineering in 2011"
TL;DR: The development of structural health monitoring (SHM) technology has evolved for over 10 years in Hong Kong since the implementation of the so-called "Wind And Structural Health Monitoring System (WASHMS)" on the suspension Tsing Ma Bridge in 1997 as discussed by the authors.
Abstract: Massive infrastructure projects developed in Hong Kong make for big challenges and unique opportunities for engineers and researchers. The construction of the cables-stayed Stonecutters Bridge sets up a new landmark in the bridge engineering community, with its main span exceeding 1,000 m as well as its sophisticated instrumentation system comprising more than 1,500 sensors. The development of structural health monitoring (SHM) technology has evolved for over 10 years in Hong Kong since the implementation of the so-called “Wind And Structural Health Monitoring System (WASHMS)” on the suspension Tsing Ma Bridge in 1997. The successful engineering paradigms of implementing and operating SHM systems for five cable-supported bridges and experiences gained by practice and research in the past decade have promoted the applications of this technology beyond Hong Kong and extending from long-span bridges to high-rise structures. In this paper, the evolution in the design methodology for SHM systems, the advanceme...
98 citations
TL;DR: In this paper, the structural performance of steel-concrete-steel (SCS) sandwich composite system subject to impact and blast load was investigated and an ice caisson protective offshore structure was proposed based on the curved sandwich panel.
Abstract: This paper investigates the structural performance of steel-concrete-steel (SCS) sandwich composite system subject to impact and blast load. Novel J-hook shear connector was invented to prevent the separation of face plates from the concrete core. SCS sandwich specimens subject to 100 kg TNT blast a 5 m standoff distance were tested. The test results are reported and the factors affecting the blast resistance of SCS sandwich structures are discussed. Finite element analysis was carried out and the numerical results are verified against the blast test results. Parametric study of sandwich core strength and plate thickness is presented. Due to the superior impact performance of the proposed SCS sandwich structures, an ice caisson protective offshore structure is proposed based on the curved sandwich panel. The ultimate strength behavior of curved SCS sandwich panels is tested. The effect of arch effect is studied both experimentally and numerically.
87 citations
TL;DR: In this article, a rectangular patch antenna, consisting of a metallic patch on one side of a dielectric substrate and a ground plane on the other side of the substrate, is studied for crack detection and monitoring.
Abstract: A major goal of structural health monitoring (SHM) is crack detection and monitoring. Because cracks are localized defects, quantifying the sizes and locations of the cracks would require placing many sensors over a large area. We present a crack sensor that is suitable for densely distributed sensor network because they can be remotely interrogated and do not need any wiring for data transmission or power supply. A rectangular patch antenna, consisting of a metallic patch on one side of a dielectric substrate and a ground plane on the other side of the substrate, is studied in this paper for crack detection and monitoring. The presence of a crack in the ground plane of the antenna changes its conductivity, which in turn reduces the resonant frequency of the antenna sensor. Experimental results demonstrated that the antenna sensor can monitor crack growth with sub-millimeter spatial resolution. Detailed experimental set-up and measurement results are presented.
45 citations
TL;DR: In this paper, the authors assess the effectiveness of a technique that aims to increase both the flexural and shear resistance of RC beams that have the bottom arm of the steel stirrups cut for the application of NSM laminates.
Abstract: Near surface mounted (NSM) technique has proved to be a very effective technique for the flexural strengthening of RC beams. Due to the relatively small thickness of the concrete cover that several beams present, cutting the bottom arm of steel stirrups for the installation of NSM laminates might be a possible strategy, whose implications on the beam's load carrying capacity need to be assessed. When steel stirrups are cut, however, the shear resistance can be a concern. This also happens when a strengthening intervention is carried out to increase the flexural resistance of a beam, since in certain cases it is also necessary to increase the shear resistance in order to avoid the occurrence of brittle shear failure. The present work assesses the effectiveness of a technique that aims to increase both the flexural and shear resistance of RC beams that have the bottom arm of the steel stirrups cut for the application of NSM laminates. This assessment is performed by experimental and numerical research. The ...
42 citations
TL;DR: In this paper, a simplified analytical model is derived based on the combination of the tests results, the numerical simulation and theoretical analysis, and the comparison between the maximum deflections at the mid-span obtained from the proposed simple analytical model and the numerical simulations shows that the proposed method gives good predictions of the predicted maximum deflection.
Abstract: This paper mainly discusses the derivation and usage of simplified analysis model of circular concrete-filled steel tube specimen under lateral impact. At first, the robust software, LS-DYNA, is employed in this paper to simulate a test of circular concrete-filled steel tube (CFT) specimen under drop impact carried out by Li (2007). The numerical simulations results agree well with the experiment results and it shows good prediction of dynamic response of the CFT specimen under lateral impact could be achieved. Further analysis based on LS-DYNA model is then made to investigate the stain rate effect of the CFT column with fixed-simple supported ends. At last, a simplified analytic model is derived based on the combination of the tests results, the numerical simulation and theoretical analysis. The comparison between the maximum deflections at the mid-span obtained from the proposed simple analytical model and the numerical simulation shows that the proposed method gives good predictions of the maximum def...
39 citations
TL;DR: In this paper, the authors present the latest design procedures for welded steel tubular truss joints subject to static and fatigue loading and present a comprehensive list of references for these joints.
Abstract: This paper presents the latest design procedures for welded steel tubular truss joints subject to static and fatigue loading. Recent research on fatigue of thin-walled tubular joints is reported. Discussion is made on thick-walled tubular joints that are used in mining equipment, bridges and wind farms. It also describes the new development in steel tubular joints such as elliptical hollow sections, cast steel, bird beak joints and composite tubular joints. A comprehensive list of references is given.
37 citations
TL;DR: In this article, a modal pushover analysis (MPA) was proposed based on the modal decoupling response spectrum method where the effect of higher-order modes was considered.
Abstract: Nonlinear static analysis (or pushover analysis) has been widely used in the last decade as a simplified and approximate method to evaluate the structural seismic performance and to estimate inelastic structural responses under severe ground motions. However most currently used pushover procedures with invariant lateral load patterns cannot fully reflect the effect of higher-order modes on structural dynamic responses. To overcome such a problem, a so-called Modal Pushover Analysis (MPA) was proposed based on the modal decoupling response spectrum method where the effect of higher modes was considered. To date, most research on MPA has been focused on frame structures. In engineering practice, however, most medium-to high-rise building structures are in the form of frame-shear-wall. Therefore it is necessary to extend the current research activity to implement the MPA to frame-shear-wall structures. In this study, two reinforced concrete frame-shear-wall structures of 10 and 18 stories are analyzed to eva...
37 citations
TL;DR: In this article, an efficient method is proposed to detect the multiple damages of structural systems, where natural frequency changes of a structure are considered as a criterion for damage presence and a multi-stage optimization approach based on the swarm intelligence algorithm is presented to accurately identify the locations and extent of eventual damages.
Abstract: An efficient method is proposed to detect the multiple damages of structural systems. Natural frequency changes of a structure are considered as a criterion for damage presence. Finite element method is also employed to evaluate the required natural frequencies. A multi-stage optimization approach based on the swarm intelligence algorithm is presented to accurately identify the locations and extent of eventual damages. Test example results demonstrate the computational advantages of the proposed method to precisely determine the sites and extent of multiple structural damages.
36 citations
TL;DR: In this paper, the concept of Basic Displacement Functions (BDFs) is introduced, which yields a mechanical based approach rather than a mathematical one for exact static analysis of arbitrarily tapered Timoshenko beams.
Abstract: Introducing the concept of Basic Displacement Functions (BDFs), an innovative method is presented which yields a mechanical based approach rather than a mathematical one for exact static analysis of arbitrarily tapered Timoshenko beams. Holding pure mechanical interpretations, BDFs are obtained using energy methods such as unit load method. It is shown that exact shape functions and consequently structural matrices could be derived in terms of BDFs. Unlike the most of finite element formulations which are based on prescribed displacement fields, the present finite element takes advantage of a flexibility basis which guarantees the exact interpolation of displacement field along the element and leads to fast convergence of the method in static analysis even with few elements. The method could be easily implemented into any standard displacement-based program. Carrying out numerical examples, the competency of the method in both static and free vibration is verified.
34 citations
TL;DR: In this article, the in-plane response of PGRM shear walls was investigated under monotonic and cyclic inplane loading cases and it was shown that the walls behave similar to URM with no significant benefit from the reinforced cores based on the displacement ductility and stiffness degradation factors derived from the complete later.
Abstract: Partially Grouted Reinforced Masonry (PGRM) shear walls perform well in places where the cyclonic wind pressure dominates the design. Their out-of-plane flexural performance is better understood than their inplane shear behaviour; in particular, it is not clear whether the PGRM shear walls act as unreinforced masonry (URM) walls embedded with discrete reinforced grouted cores or as integral systems of reinforced masonry (RM) with wider spacing of reinforcement. With a view to understanding the inplane response of PGRM shear walls, ten full scale single leaf, clay block walls were constructed and tested under monotonic and cyclic inplane loading cases. It has been shown that where the spacing of the vertical reinforcement is less than 2000 mm, the walls behave as an integral system of RM; for spacing greater than 2000 mm, the walls behave similar to URM with no significant benefit from the reinforced cores based on the displacement ductility and stiffness degradation factors derived from the complete later...
30 citations
TL;DR: In this paper, push-out tests were carried out to examine the shear strength of corrugated perfobond rib shear connections, and it was shown that the failure of the corrugation of the rib is determined by concrete bearing and small deformations of inclined rib panel.
Abstract: Push-out tests were carried out to examine the shear strength of corrugated perfobond rib shear connections. The corrugated perfobond rib shear connection, formed by folding the straight perfobond rib steel panel, can be expected to increase the shear capacity and ductility of a shear connector due to the shear resistance and deformation of the inclined rib panel. To examine the shear behaviour of the corrugated perfobond rib connection and compare it with that of the perfobond rib, the push-out specimens were fabricated to suit the shear corrugated rib resistance parameters of depth of rib, height of rib, holes in the corrugated rib and whether transverse rebar is placed in the corrugated rib holes. Results of the push-outs show that the failure of corrugated perfobond rib shear connection is determined by concrete bearing and small deformations of inclined perfobond rib panel. Specifically, the corrugated rib specimens showed different relative slips at each side of the composite interface owing to the ...
TL;DR: In this paper, the seismic response of adjacent steel structures linked to one another at different floor levels by passive devices is evaluated and two types of connectors are considered: linear viscous dampers and linear springs.
Abstract: In this study, the seismic response of adjacent steel structures linked to one another at different floor levels by passive devices is evaluated. Two types of connectors are considered: linear viscous dampers and linear springs. Various combinations of type and location of the connectors are analyzed for wide ranges of their characteristics. Influence of the structural properties (ratio of number of stories and ratio of fundamental periods) and the properties of the excitation (frequency) on the story response are also investigated. The results show that reduction of the story drift and the floor acceleration is not possible if the structures are connected to one another solely by the springs. However, it is feasible if the structures are linked to one another by either: (a) viscous dampers or (b) combinations of viscous dampers and springs. Herein, response reductions corresponding to case (b) are generally smaller than those corresponding to case (a). Also, the coupling control approach is more effectiv...
TL;DR: In this paper, the authors investigate the feasibility of deploying wireless communication and embedded computing for structural control applications and describe the experimental validation of a time-delayed decentralized structural control strategy that aims to minimize the H∞ norm of a clo...
Abstract: This study investigates the feasibility of deploying wireless communication and embedded computing for structural control applications. A feedback structural control system involves a network of sensors and control devices. As control devices are becoming smaller, more cost effective and reliable, opportunities are now available to instrument a structure with large number of control devices. However, instrumenting a large scale centralized control system with cables can be time consuming, labor intensive, and difficult to maintain and reconfigure. This study explores decentralized feedback control using wireless sensors incorporated with a computational core and a signal generation module. Decentralized control architectures are designed to make control decisions based on data acquired from sensors located in the vicinity of a control device. Specifically, this paper describes the experimental validation of a time-delayed decentralized structural control strategy that aims to minimize the H∞ norm of a clo...
TL;DR: In this article, the effects of steel fibers on the load capacity, load-deflection curve and mode of failure of NSC and HSC beams were investigated in four-point loading tests.
Abstract: The paper describes an experimental study that consisted of beam specimens made of Normal Strength Concrete (NSC) and of High Strength Concrete (HSC), with and without steel fibers that were subjected to predominant shear in four-point loading tests. HSC specimens included the four combinations of beams with and without fibers, with and without stirrups. The experimental program included study of the effects of concrete strength and inclusion of steel fibers on the load capacity, load-deflection curve and mode of failure. The results show that the effect on the shear capacity of the hooked-end steel fibers that were used in the tests was more pronounced when no shear reinforcement was used and that in the presence of stirrups fibers affected mainly the structural ductility and mode of failure. The results from the current study are also compared with the predictions of various theoretical models and of the American and European design codes. Examination of the results also shows that a required contributi...
TL;DR: In this paper, an attempt was made to predict the time-dependent behavior of RACFST columns by using the age-adjusted effective modulus method, and the effects of concrete shrinkage and creep on columns under long-term sustained loading was investigated.
Abstract: Recycled aggregate concrete-filled steel tube (RACFST) causes the recycled aggregate concrete (RAC) to be in a state of protection with the outer steel tube and thus the RAC is hardly affected by harmful environmental factors (e.g. wind, rain, moist). However, shrinkage and creep are the phenomena commonly associated with concrete-related structures, so studies on the behaviour of RACFST columns under long-term sustained loads are essential for the design of structures which include RACFST members. This study is an attempt to predict the time-dependent behaviour of RACFST columns by using the age-adjusted effective modulus method. The concrete shrinkage and creep in RACFST columns were studied experimentally, and the static bearing capacity of the tested specimens was also investigated. A theoretical model to account for the effects of concrete shrinkage and creep on RACFST columns under long-term sustained loading is developed, and comparisons of the results predicted using this model show good agreement...
TL;DR: In this paper, an experimental and numerical investigation of interlocking mortarless wall panels with 1.0 m height, 1.2 m width, and 150 mm thickness was conducted, where the panels were tested under constant precompressive vertical load and out-of-plane lateral load.
Abstract: Experimental and numerical investigation of interlocking mortarless wall panels with 1.0 m height, 1.2 m width and 150 mm thickness are conducted. Behaviour of both hollow and partially grouted masonry wall panels is studied. The panels were tested under constant pre-compressive vertical load and out-of-plane lateral load. Lateral load carrying capacity, deflection at mid height, dry joint opening between block layers and mode of failure are investigated. Strain characteristics throughout the loading process are also monitored. A finite element analysis is presented for the system and a good agreement between the experimental and modelling results is achieved. Parametric study using the finite element model is also presented and the effect of different parameters; amount of pre-compressive load and slenderness ratio is studied. The study reveals that pre-compressive vertical load and reinforcement significantly affect the structural behaviour of mortarless walls under out-of-plane loading. Useful expressi...
TL;DR: In this article, an optical fiber Bragg grating (FBG) sensing system for scour monitoring around the foundations of bridge piers and abutments is proposed, where the tensile and compressive strains of the beam are measured under a hydrodynamic pressure as water flowing around bridge foundations.
Abstract: This paper proposes an optical fiber Bragg grating (FBG) sensing system for scour monitoring around the foundations of bridge piers and abutments. The new system introduces a uniform-strength fiber-reinforced polymer (FRP) beam that is instrumented with two FBG sensors in two sides of its neutral axis. The tensile and compressive strains of the beam are measured under a hydrodynamic pressure as water flowing around bridge foundations. By assuming equal temperatures around the uniform-strength beam, the difference in wavelength variations of the two embedded FBG sensors was found to be proportional to the square of flow velocity, which is directly related to scour. A prototype scour sensing system was designed and fabricated to test its sensing property in the laboratory. The experimental results indicate that the proposed system is sensitive to flow change and further monitor the scour process effectively, without responding to its surrounding hydrostatic and soil pressures.
TL;DR: In this paper, the flexural behavior of cold-formed steel lip-reinforced built-up I-beams was investigated by finite element analysis and experimental results agree well, proving the validity of the finite element method.
Abstract: In order to investigate the flexural behavior of cold-formed steel lip-reinforced built-up I-beams, a total of 9 I-beams with three series and 3 identical specimens for each series are tested, and test specimens are simulated by finite element analysis. Results of finite element analysis and experimental results agree well, proving the validity of the finite element method in this paper. Then, substantially parametric analyses are carried out through this finite element model and the following conclusions can be obtained: the steel grade and width-to-thickness ratio of flanges have great influence on the effective width-to-thickness ratio of compression flanges, while the length of the beam, the height-to-thickness ratio of the web, and the thickness of the plate have relatively little influence. Finally, based on results of parametric analyses, effective width method and strength-reduction method on ultimate load-carrying capacity of cold-formed I-beams are proposed. Moreover, tables and equations, which...
TL;DR: In this article, an experimental program was carried out to assess the effectiveness of the near surface mounted (NSM) technique, in terms of load carrying and moment redistribution capacities, for the flexural strengthening of continuous reinforced concrete (RC) slabs, in order to verify the possibility of increasing the negative (at the intermediate support region) resisting bending moment in 25% and 50% and maintaining moment redistribution levels of 15, 30% and 45%.
Abstract: To assess the effectiveness of the near surface mounted (NSM) technique, in terms of load carrying and moment redistribution capacities, for the flexural strengthening of continuous reinforced concrete (RC) slabs, an experimental program was carried out. The experimental program is composed of three series of three slab strips of two equal span length, in order to verify the possibility of increasing the negative (at the intermediate support region) resisting bending moment in 25% and 50% and maintaining moment redistribution levels of 15%, 30% and 45%. Though the flexural resistance of the NSM strengthened sections has exceeded the target values, the moment redistribution was relatively low, and the increase of the load carrying capacity of the strengthened slabs did not exceed 25%. This experimental program is analyzed to highlight the possibilities of NSM technique for statically indeterminate RC slabs in terms of flexural strengthening effectiveness, moment redistribution and ductility performance. Us...
TL;DR: Based on the experiments on creep and shrinkage of the plain concrete used in the continuous rigid frame of Sutong Bridge, China, the applicability of ACI 209-82, JTG D62-2004, B3 and GL2000 prediction model for high-strength concrete is evaluated.
Abstract: It is important to accurately estimate creep and shrinkage effects in longspan continuous box girder bridges. Based on the experiments on creep and shrinkage of the plain concrete used in the continuous rigid frame of Sutong Bridge, China, the applicability of ACI 209-82, JTG D62-2004, B3 and GL2000 prediction model for creep and shrinkage on the high-strength concrete is evaluated. Also, a modified model based upon JTG D62-2004 is presented. Results indicate that the accuracy of prediction of creep and shrinkage can be enhanced greatly by carrying out short-term creep and shrinkage measurements on the given concrete and modifying the prediction model parameters accordingly. Furthermore, the presence of steels can have an impact on the time-dependent deformations caused by creep and shrinkage, accordingly, the restraint influence of steels on creep and shrinkage is investigated through the reinforced specimens with different reinforcement ratio. Formulas of influence coefficients of steels on creep and sh...
TL;DR: In this article, the authors measured the roughness of steel flanges and webs of three severely corroded steel beams that were recovered from a petrochemical site and found that the measured roughness increases linearly with the depth of corrosion.
Abstract: In this study seventy six standard specimens were taken from flanges and webs of three severely corroded steel beams that were recovered from a petrochemical site. The specimens were measured carefully for data on depth of corrosion and corrosion pitting; and also they were subjected to cyclic loads using a servo-hydraulic machine in order to obtain each specimen's fatigue capacity. Because of the irregularities on corroded surfaces, the measured roughness was expressed as maximum roughness, Rmax, mean roughness, Rm, and standard deviation of roughness, Sd. These measurements were found to increase linearly with increase in corrosion depth. It was observed from fatigue tests that there is a reduction in fatigue life of corroded steel specimens with corrosion pitting that are due to the "notch factor" effect. This method can indirectly yield a quantitative relationship between the pitting corrosion and the corresponding remaining fatigue life of a corroded steel structure by simple measuring of the loss in...
TL;DR: In this paper, two new BRBs, i.e. TJI-type and TJII-type, were developed at Tongji University, and full scale cyclic test results demonstrated stable hysteretic behavior and substantial energy dissipation capacity of the new-type BRBs.
Abstract: Two new-type BRBs, i.e. TJI-type and TJII-type, were developed at Tongji University. TJI-type was designed for small load-carrying applications while TJII-type for large ones. Full scale cyclic test results demonstrated stable hysteretic behavior and substantial energy dissipation capacity of the new-type BRBs. Hysteretic model and stiffness equation were established for the new-type BRBs, being capable of simulating accurately experimental behavior of the BRBs under low cyclic loading. BRB-moment frames (BRBF) and ordinary concentrically braced frames (CBF) were compared by means of elasto-plastic seismic analysis on a typical 8-story building, showing that under severe earthquakes BRB acted as structural “fuse”, to protect beams and columns from significant yielding, while ordinary braces buckled, and led to large amount of plastic hinges occurring in beams and columns and inter-story drift larger than 1/50. As an alternative application of BRBs, the structural system of simple-connected steel frame wit...
TL;DR: In this article, the authors developed a two-dimensional full-interaction moment-curvature approach to model the three-dimensional behavior of reinforced concrete, which relies on a large amount of empirical calibration to ensure a safe design.
Abstract: Much of the early research in reinforced concrete dealt with steel reinforcement that was both ductile and had a very strong bond with the concrete. Hence partial-interaction, that is slip between the reinforcement and concrete and subsequently debonding, has not been a major issue. This has allowed researchers to develop the two-dimensional full-interaction moment-curvature approach to model the three-dimensional behaviour of reinforced concrete. It is shown in this paper that this two-dimensional full-interaction moment-curvature approach relies on a large amount of empirical calibration to ensure a safe design. Furthermore, it is shown that a three-dimensional partial-interaction moment-rotation approach can lead to more advanced structural mechanics models of reinforced concrete behaviours and subsequently better accuracy and more versatile models.
TL;DR: In this article, a multi-phase study on the vibration performance of cold-formed steel floors performed at the University of Waterloo is presented, where floor framing details that enhance the floor performance against vibrations are discussed.
Abstract: Floor vibration due to walking as a serviceability concern has not been well addressed in design and construction of lightweight floors. The high strength and stiffness of steel provide the advantage of achieving longer floor spans. However, floors with longer span and lighter weight are likely to be susceptible to annoying vibrations induced by normal human activity such as walking. Designing a lightweight floor to control these annoying vibrations can be difficult due to lack of appropriate design guidelines. Presented in this paper is a multi-phase study on the vibration performance of cold-formed steel floors performed at the University of Waterloo. Full-scale floor systems with different framing details were constructed and tested in both laboratory and in situ conditions. The floor framing details that enhance the floor performance against vibrations are discussed. The results of the tests show that cold-formed steel floor systems with appropriate design and construction details can perform well aga...
TL;DR: In this paper, a spectral element model updating procedure is presented to identify damage in a structure using Guided Wave propagation results, where two damage spectral elements (DSE1 and DSE2) are developed to model the local (cracks in reinforcement bar) and global (debonding between reinforcement bar and concrete) damage in one-dimensional homogeneous and composite waveguide, respectively.
Abstract: A spectral element model updating procedure is presented to identify damage in a structure using Guided wave propagation results. Two damage spectral elements (DSE1 and DSE2) are developed to model the local (cracks in reinforcement bar) and global (debonding between reinforcement bar and concrete) damage in one-dimensional homogeneous and composite waveguide, respectively. Transfer matrix method is adopted to assemble the stiffness matrix of multiple spectral elements. In order to solve the inverse problem, clonal selection algorithm is used for the optimization calculations. Two displacement-based functions and two frequency-based functions are used as objective functions in this study. Numerical simulations of wave propagation in a bare steel bar and in a reinforcement bar without and with various assumed damage scenarios are carried out. Numerically simulated data are then used to identify local and global damage of the steel rebar and the concrete-steel interface using the proposed method. Results sh...
TL;DR: In this paper, three tests were performed on steel reinforced concrete (SRC) column to SRC beam joints subjected to fire scenarios including heating and cooling phases, and the thermal part of the test results as well as the spalling observations were reported.
Abstract: Three tests were performed on steel reinforced concrete (SRC) column to SRC beam joints subjected to fire scenarios including heating and cooling phases, and this paper reports the thermal part of the test results as well as the spalling observations. As these joints were designed to investigate the behaviour of a big joint zone including part of the beams and columns connected, temperatures in the junction and areas certain distance away from the junction were measured during both the heating and cooling phases. The three tests tested the influence of heating time on the temperature distributions at various sections of the specimen. A three-dimensional finite element analysis (FEA) model is developed to calculate the temperature field of the SRC column to SRC beam joints. The predicted temperatures show good comparison with the test results. Based on the finite element analysis, the differences of the temperature distributions in the joint zone and the non-joint zone are analyzed and its influence to the...
TL;DR: A new eigen-level data fusion model, whereby rough set data and a probabilistic neural network are integrated using a data fusion technique, is proposed for structural damage detection, which not only has good damage detection capability and noise tolerance, but also significantly reduces data storage memory requirements and saves runtime.
Abstract: In this paper, a new eigen-level data fusion model, whereby rough set data and a probabilistic neural network (PNN) are integrated using a data fusion technique, is proposed for structural damage detection. This model is used for structural damage detection and identification, particularly for cases where the measurement data has many uncertainties. More specifically, structural modal parameters derived from vibration responses are first discretized by the K-means clustering technique and the rough set technique is then employed to deal with the great volume of data and to extract optimal feature parameters. After that, the processed data and information are input to the fusion centre of the data fusion technique and fused with the PNN to give a fusion-based damage detection result. To verify the proposed method, two numerical examples are presented to identify both single and multi-damage case patterns. The effects of measurement noise and of non pre-processed rough set data on the damage detection resul...
TL;DR: In this paper, the authors presented the low-cyclic reversed tests and numerical simulation on partially prefabricated laminated composite reinforced concrete (RC) walls through the experiments, and further simulation was conducted on the composite walls and the common cast-in-place wall under different axial forces.
Abstract: This paper presents the low-cyclic reversed tests and numerical simulation on partially prefabricated laminated composite reinforced concrete (RC) walls. The specimens include 4 typical composite walls without openings, 4 with openings, and 1 common cast-in-place RC wall. The structural behaviours including failure pattern, lateral load-top drift relationship and the in-plane horizontal load carrying capacity of the composite RC walls were compared with the common cast-in-place RC walls through the experiments. Then the finite element software ABAQUS was employed to simulate the experiment scenarios. The simulation results are consistent with the experimental results. After that, further simulation was conducted on the composite walls and the common cast-in-place wall under different axial forces. Experimental and numerical study indicates that there is no obvious difference in horizontal load carrying capacity and failure pattern between the composite walls and the common cast-in-place walls under the te...
TL;DR: In this article, a simple indeterminate strut-tie model which reflects all characteristics of the ultimate strength and behavior of the deep beams was presented, and a load distribution ratio, defined as the fraction of load transferred by a truss mechanism, was also proposed to help structural designers perform the rational design of deep beams by using the strut tie model approaches of current design codes.
Abstract: The ultimate strength of simply supported reinforced concrete deep beams is governed by the capacity of the shear resistance mechanism. The structural behavior of the deep beams is controlled mainly by the mechanical relationships between the primary design variables including shear span-to-effective depth ratio, flexural reinforcement ratio, and the compressive strength of concrete. In this study, a simple indeterminate strut-tie model which reflects all characteristics of the ultimate strength and behavior of the deep beams was presented. A load distribution ratio, defined as the fraction of load transferred by a truss mechanism, was also proposed to help structural designers perform the rational design of deep beams by using the strut-tie model approaches of current design codes. In the determination of the load distribution ratio, a concept of balanced shear reinforcement ratio which ensures the ductile shear design of the deep beams was introduced, and the effect of the primary design variables was r...
TL;DR: A Model Updating Cognitive Systems (MUCogS) is introduced as a new paradigm for model updating of structural systems with incomplete data and a methodology used to identify regions of high probability without the need of calculating the complete likelihood using Modeling to Generate Alternatives (MGA).
Abstract: Developing numerical models of existing structural systems is challenging because of the uncertainty inherent on the development of the numerical model and the estimation of the structural parameters. This uncertainty is a combination of lack of knowledge (epistemic uncertainty) and inherent randomness on the system. This paper introduces a Model Updating Cognitive Systems (MUCogS) as a new paradigm for model updating of structural systems with incomplete data. MUCogS seeks to merge the computational power of computers with the analytical power of the analyst. In most cases, the posterior probability density function (PDF) within a Bayesian framework has one region of high probability. However, several regions of high probability can be obtained on the likelihood when data is incomplete. These areas can be considered by the analyst to enhance his/her knowledge about the structure. This paper discusses a methodology used to identify these regions of high probability without the need of calculating the comp...