Showing papers in "Journal of Structural Engineering-asce in 2002"
TL;DR: In this paper, a formal probabilistic framework for seismic design and assessment of structures and its application to steel moment-resisting frame buildings is presented, based on realizing a performance objective expressed as the probability of exceeding a specified performance level.
Abstract: This paper presents a formal probabilistic framework for seismic design and assessment of structures and its application to steel moment-resisting frame buildings. This is the probabilistic basis for the 2000 SAC Federal Emergency Management Agency ~FEMA! steel moment frame guidelines. The framework is based on realizing a performance objective expressed as the probability of exceeding a specified performance level. Performance levels are quantified as expressions relating generic structural variables ''demand'' and ''capacity'' that are described by nonlinear, dynamic displacements of the structure. Common probabilistic analysis tools are used to convolve both the randomness and uncertainty characteristics of ground motion intensity, structural ''demand,'' and structural system ''capacity'' in order to derive an expression for the probability of achieving the specified performance level. Stemming from this probabilistic framework, a safety-checking format of the conventional ''load and resistance factor'' kind is developed with load and resistance terms being replaced by the more generic terms ''demand'' and ''capacity,'' respectively. This framework also allows for a format based on quantitative confidence statements regarding the likelihood of the performance objective being met. This format has been adopted in the SAC/FEMA guidelines.
1,580 citations
TL;DR: In this article, the seismic performance of a posttensioned energy dissipating (PTED) connection for steel frames is investigated analytically and experimentally, and a simple design procedure for PTED connections is described.
Abstract: The seismic performance of a posttensioned energy dissipating (PTED) connection for steel frames is investigated analytically and experimentally. The PTED connection incorporates posttensioned high-strength bars to provide a self-centering response along with energy dissipating bars that are able to yield in axial tension and compression. The analytical study involves the development of an equivalent iterative sectional analysis procedure to predict the moment-rotation relationship of the PTED connection. Based on this analytical model, a simple design procedure for PTED connections is described. In the experimental study, a cyclic component test was performed on two energy dissipating bars and a cyclic test was conducted on a large-scale exterior beam-to-column PTED connection. The results of the tests show that the PTED test specimen was able to undergo large inelastic deformations without any damage in the beam or column and without residual drift. The proposed analytical model and design procedure wer...
448 citations
TL;DR: In this paper, the behavior of a type of building popular in high seismic zones with a lateral load-resisting system consisting of masonry-infilled reinforced concrete (RC) frames was investigated.
Abstract: This paper presents research on the behavior of a type of building popular in high seismic zones with a lateral-load-resisting system consisting of masonry-infilled reinforced concrete (RC) frames. Older buildings of this type typically were designed for gravity loads in combination with insufficient or no lateral loads, therefore they do not meet current seismic code requirements. Also, the participation of infill panels in the lateral load resistance of RC frames was not recognized in the original design, often resulting in an overly conservative design. In an attempt to determine the seismic vulnerability of this type of structure, an experimental program was carried out to evaluate the behavior of five half-scale, single-story laboratory models with different numbers of bays. The results indicated that infilled RC frames exhibit significantly higher ultimate strength, residual strength, and initial stiffness than bare frames without compromising any ductility in the load-deflection response. Furthermore, the number of bays appears to be influential with respect to the peak and residual capacity, the failure mode, and the shear stress distribution.
399 citations
TL;DR: In this paper, a closed-form prediction of the buckling stress in the local mode, including interaction of the connected elements, and the distortional mode including consideration of the elastic and geometric stiffness at the web/flange juncture, is provided and shown to agree well with numerical methods.
Abstract: Open cross-section, thin-walled, cold-formed steel columns have at least three competing buckling modes: local, distortional, and Euler ~i.e., flexural or flexural-torsional ! buckling. Closed-form prediction of the buckling stress in the local mode, including interaction of the connected elements, and the distortional mode, including consideration of the elastic and geometric stiffness at the web/flange juncture, are provided and shown to agree well with numerical methods. Numerical analyses and experiments indicate postbuckling capacity in the distortional mode is lower than in the local mode. Current North American design specifications for cold-formed steel columns ignore local buckling interaction and do not provide an explicit check for distortional buckling. Existing experiments on cold-formed channel, zed, and rack columns indicate inconsistency and systematic error in current design methods and provide validation for alternative methods. A new method is proposed for design that explicitly incorporates local, distortional and Euler buckling, does not require calculations of effective width and/or effective properties, gives reliable predictions devoid of systematic error, and provides a means to introduce rational analysis for elastic buckling prediction into the design of thin-walled columns.
326 citations
TL;DR: Many theoretical and experimental studies have been carried out on fiber-reinforced plastic (FRP)-confined circular concrete specimens, leading to a variety of models for predicting their axial com...
Abstract: Many theoretical and experimental studies have been carried out on fiber-reinforced plastic (FRP)-confined circular concrete specimens, leading to a variety of models for predicting their axial com...
322 citations
TL;DR: In this article, a wavelet packet transform (WPT) based method is proposed for the damage assessment of structures, where the dynamic signals measured from a structure are first decomposed into wavelet component and then calculated and used as inputs into neural network models for dama.
Abstract: Wavelet transform (WT) is a mathematical tool that can decompose a temporal signal into a summation of time-domain basis functions of various frequency resolutions. This simultaneous time-frequency decomposition gives the WT a special advantage over the traditional Fourier transform in analyzing nonstationary signals. One drawback of the WT is that its resolution is rather poor in the high-frequency region. Since structural damage is typically a local phenomenon captured most likely by high frequency modes, this potential drawback can affect the application of the wavelet-based damage assessment techniques. The wavelet packet transform (WPT) adopts redundant basis functions and hence can provide an arbitrary time-frequency resolution. In this study, a WPT-based method is proposed for the damage assessment of structures. Dynamic signals measured from a structure are first decomposed into wavelet packet components. Component energies are then calculated and used as inputs into neural network models for dama...
310 citations
TL;DR: In this paper, the axial load behavior of concrete-filled steel tubular (CFT) columns with the width-to-thickness ratios between 40 and 150 was investigated and an effective stiffening scheme was proposed to improve the mechanical properties of square cross-sectional CFT columns.
Abstract: This study investigates the axial load behavior of concrete-filled steel tubular (CFT) columns with the width-to-thickness ratios between 40 and 150, and proposes an effective stiffening scheme to improve the mechanical properties of square cross-sectional CFT columns. Seventeen specimens were tested to examine the effects of cross-sectional shapes, width-to-thickness ratios, and stiffening arrangements on the ultimate strength, stiffness, and ductility of CFT columns. Moreover, nonlinear finite element analysis was also conducted to investigate cross-sectional axial stress distribution at the ultimate strength. Comparing the measured ultimate strength with estimates by using some current specifications suggested that current specifications may considerably underestimate the ultimate strength of circular CFT columns, particularly for columns with a small width-to-thickness ratio. Results in this study demonstrate that the proposed stiffening scheme can significantly enhance the ultimate strength and ducti...
281 citations
TL;DR: In this article, a damage identification technique based on changes in frequencies and mode shapes of vibration is proposed for predicting damage location and severity, which is applied at an element level with a conventional finite-element model.
Abstract: The change of modal characteristics directly provides an indication of structural damage. Based on changes in frequencies and mode shapes of vibration, a damage identification technique is proposed in this paper for predicting damage location and severity. The method is applied at an element level with a conventional finite-element model. The element damage equations have been established through the eigenvalue equations that characterize the dynamic behavior. Several solution techniques are discussed and compared. The influence of simulated noise in the modal data is also presented. The method has been verified by a number of damage scenarios for simulated beams and has found the exact location and severity of damage. It is demonstrated that multiplying the damaged eigenvalue equations with the undamaged or damaged mode shapes provides more equations and guarantees the damage localization. The resulting equations, however, become more sensitive to the deviation of modal data and the direct solution often...
274 citations
TL;DR: In this paper, the buckling mechanism of reinforcing bars was investigated using fine element microanalysis using fiber technique and it was found that reinforcing bars under inelastic axial compression exhibit later deformation defined as buckling due to the geometrical nolinearity.
Abstract: Finite element microanalysis using fiber technique was carried out to study the buckling mechanism of reinforcing bars. It was found that reinforcing bars under inelastic axial compression exhibit later deformation defined as buckling due to the geometrical nolinearity. Further investigation revealed that the postbuckling average compressive stress is less than the local stress corresponding to the same strain due to the different striffness for loading and unloading fibers in the laterally deformed section. It was clarified that the average compressive stress-strain relationship including the softening in the postbuckling range can be completely described in terms of the product of square root of yield strength and the slenderness ration of the reinforcing bar. Moreover, a unique relationship between the average stress and average strain of reinforcing bars including the effect of buckling is established through various parametric analyses. The comparison of the analytical results and proposed model with some experimental results showed good agreement, thus verifying the reliability of the microanalysis and proposed computational model.
259 citations
TL;DR: In this article, a post-tensioned wide flange beam-to-column connection for steel moment resisting frames subjected to seismic loading conditions is presented, which includes top and seat angles bolted to the beam and column.
Abstract: Nine large-scale subassembly tests were conducted to investigate the behavior of an innovative posttensioned wide flange beam-to-column connection for steel moment resisting frames subjected to seismic loading conditions. The connection includes top and seat angles bolted to the beam and column. Strands are placed along the length of the beam, passing through the column and posttensioned to provide a precompression of the beam against the column. The parameters investigated in the study include the angle thickness, angle gage length, beam flange reinforcing plates, connection shim plates, and posttensioning force. The test results demonstrate that posttensioned connections provide excellent elastic stiffness, strength, and ductility under cyclic loading, with energy dissipation occurring primarily in the angles. The connection initial elastic stiffness is comparable to that of a fully restrained welded connection. In addition, the connection has essentially no residual deformation following several cycles...
252 citations
Abstract: Critical issues related to damage and condition assessment are discussed. The distinction between global and local state properties, linearized and nonlinear condition indices and experimental constraints are discussed along with a classification of condition assessment techniques. Brief examples from research results on steel stringer highway bridges and a long span bridge are presented in order to exemplify the interrelation between structural condition, damage, and some of the promising damage indices. The indices that are discussed in this paper are influence coefficients for displacement and strain, and redistribution of intrinsic strains measured by continuous long-term monitoring. A discussion of these indices is introduced with application examples from the bridges, which were utilized as a test bed to evaluate the applicability of the indices. Tools and technologies for successful measurement of influence coefficients are presented. It is shown that if a spectrum of appropriate experiments and indices are integrated within a structural identification framework, and the structure is monitored for a sufficiently long time, it is possible to accomplish successful condition and damage assessment.
TL;DR: In this paper, a performance prediction and evaluation procedure based on nonlinear dynamics and reliability theory is presented, which features full integration over the three key stochastic models: ground motion hazard curve, nonlinear dynamic displacement demand, and displacement capacity.
Abstract: A performance prediction and evaluation procedure based on nonlinear dynamics and reliability theory is presented. It features full integration over the three key stochastic models: ground motion hazard curve, nonlinear dynamic displacement demand, and displacement capacity. Further, both epistemic and aleatory uncertainties are evaluated and carried through the analysis. A suite of uncertainty analyses are input to the procedure such as period, live load, material properties, damping, analysis procedure, and orientation of the structure. Two limit states are defined instead of the traditional single state. The procedure provides a simple method for estimating the confidence level for satisfying the performance level for a given hazard. The confidence level of a post- and a pre-Northridge nine-story building for a given hazard level is calculated using the procedure described in the paper. New steel moment frame buildings are expected to perform much better during major earthquakes than existing buildings designed and built with older technologies.
TL;DR: In this paper, a simplified metho-means of discontinuities caused by abrupt changes in cross-sectional dimensions or by concentrated loads result in discontinuity regions due to disturbance in the flow of internal forces.
Abstract: Discontinuities caused by abrupt changes in cross-sectional dimensions or by concentrated loads result in discontinuity regions due to disturbance in the flow of internal forces. A simplified metho...
TL;DR: In this paper, the authors describe the vortex-induced vibration that occurred in these particular spans, together with the extensive number of wind tunnel tests that were conducted before and after the bridge construction.
Abstract: The Trans-Tokyo Bay Highway Crossing, completed in 1997, is 11 km in total length and is a combined tunnel and multiple bridge route that includes a ten-span continuous steel box-girder bridge with a total length of 1,630 m. The two longest spans of this bridge measure 240 m, and the highway consists of four lanes with an overall width of 22.9 m. In this bridge, significant vibration due to vortex shedding was observed under prevailing winds almost transverse to the bridge axis. This vortex-induced first-mode vibration peaked at a wind velocity around 16-17 m/s, with a maximum amplitude exceeding 50 cm. This paper describes the vortex-induced vibration that occurred in these particular spans, together with the extensive number of wind tunnel tests that were conducted before and after the bridge construction. It is shown that the results from the field and from the wind tunnel tests are fairly consistent regarding the amplitudes and wind speed range of the vortex-induced vibration in the first vertical vibrational mode of the bridge. The TMDs developed specifically to control first and second vertical flexural modes of this bridge and aerodynamic vibration controls employed for higher modes are also explained.
TL;DR: In this article, a recurrent neural network (NN) model is proposed to emulate the inverse dynamics of the magnetorheological (MR) damper, which can be used to estimate the required voltage to be input to the damper so that a desirable damper force can be produced.
Abstract: The dynamic behavior of a magnetorheological (MR) damper is well portrayed using a Bouc–Wen hysteresis model. This model estimates damper forces based on the inputs of displacement, velocity, and voltage. In some control applications, it is necessary to command the damper so that it produces desirable control forces calculated based on some optimal control algorithms. In such cases, it is beneficial to develop an inverse dynamic model that estimates the required voltage to be input to the damper so that a desirable damper force can be produced. In this study, we explore such a possibility via the neural network (NN) technique. Recurrent NN models will be constructed to emulate the inverse dynamics of the MR damper. To illustrate the use of these NN models, two control applications will be studied: one is the optimal prediction control of a single-degree-of-freedom system and the other is the linear quadratic regulator control of a multiple-degree-of-freedom system. Numerical results indicate that, using t...
TL;DR: In this article, a damage identification scheme is developed using the mode-based damage identification method described in an accompany paper, which is applied to the experimental data and the consequent results are compared.
Abstract: Most of the mode-based damage identification techniques have been well verified by numerical simulations. However, many of them still face problems when applied to real measurements where noise is present. In this paper, an experimental program of a reinforced concrete beam is aimed to establish the relation between damage and changes of the structural dynamic characteristics. A damage identification scheme is developed using the mode-based damage identification method described in an accompany paper. The proposed damage identification scheme is applied to the experimental data and the consequent results are compared. It is demonstrated that the proposal of a realistic damage pattern that can describe damage by few representative parameters is necessary to guarantee the localization of damage. An adaptation of the initial finite-element model is required to give the best agreement with the reference measurements. A possible advantage of the algorithm is that the modal forces can be directly extracted from any finite-element package and the mode shape expansion is involved in the damage identification scheme using a static recovery technique.
TL;DR: In this article, the flexural force-deformation behavior of high strength square concrete-filled steel tube (CFT) beam-columns was experimentally investigated, and the parameters in the study included the width-to-threshold (W2T) and the length of the beam.
Abstract: The flexural force-deformation behavior of high strength square concrete-filled steel tube (CFT) beam-columns was experimentally investigated. The parameters in the study included the width-to-thic...
TL;DR: In this article, the authors present the need for improved methodologies for engineering new light-frame structures for housing and techniques for condition assessment of existing structures, and the development of appropriate and usable fragility models and system reliability analysis tools is necessary to meet these needs and to make meaningful advances in performance-based engineering of wood frame structures.
Abstract: Recent trends in building construction have highlighted the need for improved methodologies for engineering new light-frame structures for housing and techniques for condition assessment of existing structures. The aftermath of natural disasters during the past decade, the rapid evolution of design and construction methods, and heightened expectations on the part of the public and its scrutiny of perceived and actual deficiencies in codes and code enforcement have further underscored these needs. Among the high-priority areas identified at a 1997 ASCE workshop on wood engineering research needs were behavior and performance of wood structural systems; criteria for performance assessment; and methods for condition assessment of damaged systems following natural disasters. The development of appropriate and usable fragility models and system reliability analysis tools is necessary to meet these needs and to make meaningful advances in performance-based engineering of wood frame structures. This paper provid...
TL;DR: In this paper, the effect of horizontal displacement or shear strain on critical load and the validity of the approximate correction factor was evaluated on a series of elastomeric bearing with low shape factors.
Abstract: Elastomeric isolation bearings are required to be stable at high shear strains, which occur during strong earthquakes. Hence, rigorous determination of the critical axial load during design is important. Currently, the critical load is determined using the small displacement Haringx theory and modified to account for large shear strains by an approximate correction factor. The objective of this study is to experimentally determine the effect of horizontal displacement or shear strain on critical load and to study the validity of the approximate correction factor. Experiments were conducted on a series of elastomeric bearings with low shape factors. Test procedure and test results are presented in detail. It is shown that the critical load decreases with increasing horizontal displacement or shear strain. It is also shown that substantial critical load capacity exists at a horizontal displacement equal to the width of the bearing and is not zero, as predicted by the correction factor. It is further shown that the approximate formula is not conservative at smaller displacements and overly conservative at larger displacements. The critical loads obtained from experiments are compared with results from finite element analyses and nonlinear analytical solutions; the comparisons indicate that the effect of large horizontal displacements on the critical load can be reliably predicted.
TL;DR: In this paper, an experimental study on radius cut reduced beam section (RBS) moment connections for use in seismic resistant steel moment frames was conducted, where the effects of panel zone strength, composite behavior with a concrete slab, and beam web-to-column flange connection were specifically addressed in these tests.
Abstract: This paper describes an experimental study on radius cut reduced beam section (RBS) moment connections for use in seismic resistant steel moment frames. The effects of panel zone strength, composite behavior with a concrete slab, and the beam web-to-column flange connection were specifically addressed in these tests. In total, eight double-sided specimens were designed, fabricated, and tested in this study, providing data for sixteen individual RBS connections. Each specimen was subjected to a standard quasi-static cyclic load pattern. Overall, the specimens performed well with seven of the eight achieving total (elastic plus plastic) story drift ratios of at least 0.04 radians in magnitude before experiencing 20% strength degradation. The other test was stopped due to out-of-plane instability after being loaded to 0.03 radians of total story drift. Comparison of the response of specimens with strong panel zones, balanced panel zones, and weak panel zones relative to beam strength led to the conclusion that weak panel zones allow for the most stable hysteretic response at large drift levels. Inclusion of a composite slab in these tests appeared to stabilize the beams against lateral torsional buckling with no consistently detectable increase in the strains in the bottom beam flange. Welding the beam web to the column flange seemed to decrease the likelihood of weld fracture in these specimens.
TL;DR: In this paper, an approximate method is presented to estimate the maximum lateral drift demands in multistory buildings with nonuniform lateral stiffness responding primarily in the fundamental mode when subjected to earthquake ground motions.
Abstract: An approximate method is presented to estimate the maximum lateral drift demands in multistory buildings with nonuniform lateral stiffness responding primarily in the fundamental mode when subjected to earthquake ground motions. The method is aimed at the estimation of the maximum roof displacement and of the maximum interstory drift ratio for a given response spectrum. A simplified model of the multistory building is used based on an equivalent continuum structure with nonuniform lateral stiffness distribution consisting of a combination of a flexural cantilever beam and a shear cantilever beam. The effect of the type and amount of reduction in lateral stiffness along the height of the building and of the ratio of overall flexural and shear deformations on the ratio of the spectral displacement to the roof displacement and on the ratio of the maximum interstory drift ratio to the roof drift ratio is investigated. It is shown that reductions in lateral stiffness along the height have a negligible effect o...
TL;DR: In this article, a simple and reliable method to predict the buckling length of longitudinal reinforcing bars and also to predict spalling of cover concrete in reinforced concrete members is proposed, where tie stiffness required to hold longitudinal reinforcement bars in different buckling modes is derived from energy principles and compared with actual tie stiffness to determine the stable buckling mode.
Abstract: The main aim of this study is to propose a simple and reliable method to predict the buckling length of longitudinal reinforcing bars and also to predict the spalling of cover concrete in reinforced concrete members. Stability analysis is conducted giving due consideration to both geometrical and mechanical properties of the longitudinal reinforcing bars and lateral ties. The tie stiffness required to hold longitudinal reinforcing bars in different buckling modes is derived from energy principles, and it is compared with actual tie stiffness to determine the stable buckling mode. The buckling length is computed as the product of the stable buckling mode and the tie spacing. The proposed buckling length determination method is experimentally verified for various cases. A design method for lateral ties to avoid buckling-induced strength degradation is also recommended. The effect of lateral deformation of longitudinal bars is quantitatively evaluated and incorporated in the simulation of cover concrete spal...
TL;DR: In this paper, the relative accuracy of different models, mainly intended for use by practicing engineers, for the analysis of unreinforced masonry buildings, and to determine whether, and under what conditions, a simple equivalent frame model can be used for design and/or assessment purposes, is evaluated.
Abstract: The paper aims at evaluating the relative accuracy of different models, mainly intended for use by practicing engineers, for the analysis of unreinforced masonry buildings, and to determine whether, and under what conditions, a simple equivalent frame model can be used for design and/or assessment purposes. Several parametric analyses involving finite element ~FE! models of two-dimensional and three-dimensional structures have been performed, first in the elastic range, using both refined and coarse planar meshes. They were followed by analyses of the same structures using equivalent frames with alternative arrangements of rigid offsets. Subsequently, two- dimensional nonlinear static ~pushover! analyses of both FE and equivalent frame models were performed to check the validity of the conclusions drawn from the elastic analysis. The results presented herein shed some further light on the feasibility of using simplified and cost-effective analytical models as a tool for practical design and/or assessment of typical masonry structures.
TL;DR: In this paper, an experimental and analytical study on the mechanical behavior of circular steel-concrete composite stub columns was conducted, and the results obtained from the tests and the finite-element analyses showed that the mechanical behaviour of the column was greatly influenced by the method used to apply the load to the column section.
Abstract: In an experimental and analytical study on the mechanical behavior of circular steel-concrete composite stub columns, 13 specimens were tested. To examine different mechanical behaviors of the columns, three loading conditions were studied. Three-dimensional nonlinear finite-element models were established and verified with the experimental results. The analytical models were also used to study how the behavior of the column was influenced by the bond strength between the steel tube and the concrete core and by the confinement of the concrete core offered by the steel tube. The results obtained from the tests and the finite-element analyses showed that the mechanical behavior of the column was greatly influenced by the method used to apply the load to the column section. The bond strength had no influence on the behavior when the steel and concrete section were loaded simultaneously. On the contrary, for the columns with the load applied only to the concrete section, the bond strength highly affected the confinement effects and, consequently, the mechanical behavior of the columns.
TL;DR: In this paper, the application of performance-based seismic design to wood framed buildings through a direct-displacement methodology is discussed, and a simple numerical model capable of predicting cyclic response and energy dissipation characteristics of wood shear walls under general quasi-static cyclic loading is presented.
Abstract: An important advancement in structural engineering in recent years has been the development of performance-based seismic design. However, its application to engineered wood framed buildings remains largely unexplored. This paper discusses the application of performance-based seismic design to wood framed buildings through a direct-displacement methodology. In the first part of the paper, limitations of the current force-based seismic design procedure for wood framed buildings are outlined. Thereafter, the fundamentals of displacement-based seismic design are presented along with a description of the system parameters required for its application. For the purpose of evaluating these parameters for wood framed buildings, a simple numerical model capable of predicting the cyclic response and energy dissipation characteristics of wood shear walls under general quasi-static cyclic loading is presented. The generalization of this model to three-dimensional wood framed structures is also discussed. As an application example, the displacement-based seismic design of a simple one-story shear wall building is presented. In turn, this design approach is validated by nonlinear dynamic time-history analyses using earthquake records representative of the hazard levels that were associated with the design performance levels.
TL;DR: In this paper, reinforced concrete columns can be strengthened by a fiber-reinforced polymer (FRP) jacket which provides lateral confinement to the column and is very effective for circular columns.
Abstract: Reinforced concrete columns can be strengthened by a fiber-reinforced polymer (FRP) jacket which provides lateral confinement to the column. This technique is very effective for circular columns, b...
TL;DR: In this paper, the effects of one-sided and two-sided pounding on the global response of a multiple-frame bridge due to pounding of adjacent frames were examined and it was determined that the most important parameters are the frame period ratio and the characteristic period of the ground motion.
Abstract: Pounding between adjacent frames in a multiple-frame bridge produces undesirable forces resulting in large displacements, local damage, and possible failure of column bents. In this study, analytical models are used to examine the factors affecting the global response of a multiple-frame bridge due to pounding of adjacent frames. Parameter studies of one-sided and two-sided pounding are conducted to determine the effects of frame stiffness ratio, ground motion characteristics, frame yielding, and restrainers on the pounding response of bridge frames. It is determined that the most important parameters are the frame period ratio and the characteristic period of the ground motion. The amplification in the frame response due to one-sided pounding is most severe for cases with highly out-of-phase frames, in particular for short period structures. Two-sided pounding amplifies the stiff frame response, and reduces the flexible frame response. The addition of restrainers has a minor effect on the one-sided pounding response of highly out-of-phase frames. Current recommendations by Caltrans for limitations in frame period ratios to reduce the effects of pounding are evaluated through an example case.
TL;DR: In this article, a finite-element (FE) modeling and nonlinear analysis of steel-concrete composite plate girders under negative bending and shear loading is presented. And the results obtained from the FE analysis are compared with the corresponding experimental results.
Abstract: This paper deals with finite-element (FE) modeling and nonlinear analysis of steel-concrete composite plate girders under negative bending and shear loading. A three-dimensional FE model, using a general purpose finite-element software, has been used to carry out the nonlinear analysis. One steel plate girder and four composite plate girders tested to failure by other researchers have been analyzed by the FE model proposed in the study. Various models, which attempted to overcome the difficulties in modeling of steel-concrete composite plate girders, are presented and discussed in this paper. Results obtained from the FE analysis are compared with the corresponding experimental results. It is observed from the comparison that the proposed nonlinear FE model is capable of predicting the ultimate load behavior of steel-concrete composite plate girders to an acceptable accuracy.
TL;DR: In this article, the stiffness and strength of the connection between the wooden beam and the concrete slab are theoretically assessed. But the authors focus on the structural properties of the stud connection, and do not consider the deformation control of the beam.
Abstract: The stiffening and strengthening of wood floors with a thin collaborating concrete slab is a recent technique which appears particularly suitable for restoration work on ancient buildings. This research deals with the theoretical evaluation of the stiffness and strength of the connection between the wooden beam and the concrete slab. Toward this end, both the stiffness and the strength of the connection between the wooden beam and the concrete slab are theoretically assessed. The aim of the present research work is to define a simplified approach which allows the connection design to be based on deformation control. The stud connection is studied in the general case of wooden planks separating the concrete slab and the wooden beam. The initial stiffness of the connection is evaluated on the basis of the classical approach of the beam on elastic foundation, whereas the ultimate strength is based on the collapse mechanism with two plastic hinges in the stud shank. The failure mechanism leads to the definition of the minimum stud length. The results of the theoretical formulation are in good agreement with experimental results.
TL;DR: In this article, the reduced beam section (RBS) moment connection was used to control drift in steel special moment resisting frames to control the RBS moment connection in a special moment resistent frame.
Abstract: Design engineers frequently use deep columns in steel special moment resisting frames to control drift. As the reduced beam section (RBS) moment connection is becoming popular after the 1994 Northr...