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Sensitivity Of Response Of Skewed Bridges To Their Span Length Number Of Bents And Abutment Modeling
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Book Synopsis Sensitivity of Response of Skewed Bridges to Their Span Length, Number of Bents and Abutment Modeling by : Shayan Sheikhakbari
Download or read book Sensitivity of Response of Skewed Bridges to Their Span Length, Number of Bents and Abutment Modeling written by Shayan Sheikhakbari and published by . This book was released on 2016 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sensitivity of the seismic performance of two typical bridges to the modeling variation of their abutment parameters is investigated and compared through a comparison parameter proposed in this study. One of the bridges is a two-span two-column-bent bridge with seat-type skew abutment and the other is a three-span three-column-bent bridge with seat-type skew abutment. A set of 40 pulse-like ground motions is applied to the bridges for nonlinear time-history analysis.In the transverse direction, two force-deformation models, which are based on strut-and-tie and sliding shear friction mechanisms, are used. The analytical models are based on the extensive experimental research previously conducted.A hyperbolic force-deformation model (General Hyperbolic Force Deformation) is used to represent the passive lateral resistance of the abutment backfill. For considering the possible variation in the backfill geotechnical property, three typical abutment backfill is chosen from the exciting data that was collected from multiple highway bridges in California. Two alternative methods are used to account for the effect of the abutment skew angle on the backfill reaction. The methods include an empirical relationship derived from experimental data, and an analytical method developed based on assumed log-spiral soil failure mechanism.A comparison parameter is proposed in this study, which is a representative of ductility demand of a skewed bridge to the same non-skewed bridge. For each case, the parameter is computed using the data derived from the nonlinear time-history analysis to investigate the seismic performance of bridges and compare the ductility demand of the specimen bridges.The outcome of this research reveals the significance of shear keys and abutment backfill on the global response of bridges. The sensitivity of the comparison parameter to the specimen bridges' geometry is also discussed in detail in this study.
Book Synopsis Performance-based Seismic Assessment of Skewed Bridges by : Peyman Kavianijopari
Download or read book Performance-based Seismic Assessment of Skewed Bridges written by Peyman Kavianijopari and published by . This book was released on 2011 with total page 279 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study focuses on identifying, both qualitatively and quantitatively, the seismic behavior of reinforced concrete bridges with seat-type abutments under earthquake loading, especially with respect to abutment skew angle. To that end, the study proposes novel methodologies for modeling skew-angled seat-type abutments and for seismic response assessment of structures whose response is characterized as "multi-phased." The proposed methodologies are applied to a comprehensive database of bridges with combinations of a variety of bridge geometric properties, including: (1) number of spans; (2) number of columns per bent; (3) column-bent height; (4) span arrangement; and (5) abutment skew angle. An extensive nonlinear response history analysis was conducted using three sets of ground motions representing records for rock sites and soil sites, as well as others that contained pronounced velocity pulses, denoted as "pulse-like." We demonstrate that demand parameters for skew-abutment bridges, such as deck rotation, abutment unseating, and column drift ratio, are higher than those for straight bridges. By investigating the sensitivity of various response parameters to variations in bridge geometry and ground motion characteristics, we show that bridges with larger abutment skew angles bear a higher probability of collapse due to excessive rotation, and that shear keys can play a major role in reducing deck rotations and thus the probability of collapse. We further show that resultant peak ground velocity (PGVres) is the most efficient ground motion intensity measure (IM) compared to many other IMs. In view of the skewed bridges' explicit changes in demand parameter behavior due to shear key failure, we propose a probabilistic-based approach for multi-phase structural response assessment. This method, denoted as "Multi-Phase Probabilistic Assessment of Structural Response to Seismic Excitations," or M-PARS, provides a probabilistic framework for computing the complementary probability distribution function of an engineering demand parameter given the ground motion intensity measure, G(EDP\IM).
Author :Robert J. Frosch Publisher :Joint Transportation Research Program ISBN 13 :9781622600120 Total Pages :149 pages Book Rating :4.6/5 (1 download)
Book Synopsis Long-Term Behavior of Integral Abutment Bridges by : Robert J. Frosch
Download or read book Long-Term Behavior of Integral Abutment Bridges written by Robert J. Frosch and published by Joint Transportation Research Program. This book was released on 2011-08-15 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: Integral abutment (IA) construction has become the preferred method over conventional construction for use with typical highway bridges. However, the use of these structures is limited due to state mandated length and skew limitations. To expand their applicability, studies were implemented to define limitations supported by rational analysis rather than simply engineering judgment. Previous research investigations have resulted in larger length limits and an overall better understanding of these structures. However, questions still remain regarding IA behavior; specifically questions regarding long-term behavior and effects of skew. To better define the behavior of these structures, a study was implemented to specifically investigate the long term behavior of IA bridges. First, a field monitoring program was implemented to observe and understand the in-service behavior of three integral abutment bridges. The results of the field investigation were used to develop and calibrate analytical models that adequately capture the long-term behavior. Second, a single-span, quarter-scale integral abutment bridge was constructed and tested to provide insight on the behavior of highly skewed structures. From the acquired knowledge from both the field and laboratory investigations, a parametric analysis was conducted to characterize the effects of a broad range of parameters on the behavior of integral abutment bridges. This study develops an improved understanding of the overall behavior of IA bridges. Based on the results of this study, modified length and skew limitations for integral abutment bridge are proposed. In addition, modeling recommendations and guidelines have been developed to aid designers and facilitate the increased use of integral abutment bridges.
Book Synopsis Dynamics of Civil Structures, Volume 4 by : Fikret Necati Catbas
Download or read book Dynamics of Civil Structures, Volume 4 written by Fikret Necati Catbas and published by Springer Science & Business Media. This book was released on 2014-04-15 with total page 831 pages. Available in PDF, EPUB and Kindle. Book excerpt: This fourth volume of eight from the IMAC - XXXII Conference, brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Structural Dynamics, including papers on: Linear Systems Substructure Modelling Adaptive Structures Experimental Techniques Analytical Methods Damage Detection Damping of Materials & Members Modal Parameter Identification Modal Testing Methods System Identification Active Control Modal Parameter Estimation Processing Modal Data
Book Synopsis Bias and Sensitivity of Nonlinear Models for Seismic Response of Ordinary Standard Bridges by : Andres F. Rodriguez
Download or read book Bias and Sensitivity of Nonlinear Models for Seismic Response of Ordinary Standard Bridges written by Andres F. Rodriguez and published by . This book was released on 2020 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: The bias analysis of the nonlinear model concluded that both software agreed after improving the hinge length and the inclusion of gaps in the abutments. The same SAP2000 models were used to analyze the sensitivity of the most representative nonlinear parameters in the columns, superstructure, and abutments, as well as sensitivity to the hysteresis behavior of the concrete and the reinforcement steel. The prediction of the sensitivity was obtained applying the finite difference method, perturbing each parameter forward and backward by a coefficient of variation. The results obtained indicate that the selected bridges have a strong sensitivity in the longitudinal direction to the hysteretic assumptions and to small variations in parameters such as steel yield strength, superstructure Young’s modulus, and abutment strength, while the displacement response in the transversal direction seems to be insensitive.
Book Synopsis The Structural Analysis, Design, and Prototype Testing of Three-sided Small-span Skewed Bridges by : Daniel N. Farhey
Download or read book The Structural Analysis, Design, and Prototype Testing of Three-sided Small-span Skewed Bridges written by Daniel N. Farhey and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An analytical study was carried out for the structural performance assessment of precast-concrete, short-span, skewed bridges with integral abutment walls. Typically, these structures are designed as simplified two-dimensional rigid portal frames, neglecting the degrading effects of the skew angle and laterally unsymmetrical vertical loading. This design practice produces under-designed bridges for certain aspect ratios, causing cracking and local deterioration symptoms, observed in some instances out in the field. To evaluate the limitations of this practice, three-dimensional finite-element models were developed and analyzed. Accordingly, these finite-element models simulate various geometric configuration parameters, as well as, laterally symmetrical and unsymmetrical vertical load conditions, capturing the amplification of the structural response. Field-testing was also performed on a bridge to substantiate and calibrate the finite-element results. The results of the simplified plane frame analyses and three-dimensional finite-element analyses were presented in correlation diagrams, enabling simple comparison and quantification. The correlation diagrams provide correction factors to amend the simple frame design. The response observations offer a qualitative insight into the actual behavior of the structure, allowing the performance assessment of existing bridges of the same type and a more reliable design in the future.
Book Synopsis Modeling the Coupled Cyclic Translational and Rotational Responses of Skew Bridge Abutment Backfills by : Seyedali Nojoumi
Download or read book Modeling the Coupled Cyclic Translational and Rotational Responses of Skew Bridge Abutment Backfills written by Seyedali Nojoumi and published by . This book was released on 2016 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abutments are bridge-supporting structures at the interface of the bridge deck and the soil embankment. During strong seismic events, longitudinal motion of the bridge causes a collision between the deck and the abutment backwall--which is lightly reinforced and is designed to break--and plastic deformations are induced in the backfill. This mechanism is intended to dissipate energy, and concentrate or limit the seismic damage to the abutments (Caltrans SDC, 2010). Reversals of inertial forces can cause the deck to unseat from the abutment, and thus, sufficient seat length is required. Seat type abutments also feature exterior shear keys that are used to counter possible transverse deck movements. They are proportioned and detailed to act as fuses that will break off under the design earthquake (Kaviani et al., 2014).
Book Synopsis Engineering Mechanics by : Stein Sture
Download or read book Engineering Mechanics written by Stein Sture and published by . This book was released on 1995 with total page 754 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Thermal Response of Skewed Bridges by :
Download or read book Thermal Response of Skewed Bridges written by and published by . This book was released on 1990 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bridges may experience large movements or stresses when exposed to environmental conditions. Large stresses occur when thermal movements are prevented, and as a result inaccurate estimation of these movements may lead to damage of the bridge. The damage may, in turn, lead to expensive repairs, increased maintenance cost, and reduced service life of the structure. It is relatively easy to estimate the thermal movements in straight, non-skew bridges. The movements of a simple bridge can be estimated by a relatively simple equation based on the length of the bridge, the coefficient of thermal expansion and the maximum temperature changed expected for that environment. Skewed bridges, however, have more complex thermal response; their thermal movements may surprise many bridge engineers. A recent study of State Departments of Transportation have identified a number of such bridges. The Casper Creek Bridge in Casper, Wyoming, is one such bridge. The bridge is described, and the deformation and damage which have been noted are examined. A series of computer analyses is discussed. The mathematical modelling is described in detail, and the alternate models are compared to the real structure. The results of the analyses are correlated to observed behaviour. These calculations lead to a rational explanation of the cause of the unusual behaviour. Methods of alleviating the problem and avoiding similar problems in the future are evaluated. For the covering abstract of the Conference see IRRD Abstract no. 807839.
Book Synopsis Three Dimensional Finite Element Modeling Techniques and Their Effect on the Seismic Response of a Highly Skewed Multi-span Bridge by : James D. Kelley
Download or read book Three Dimensional Finite Element Modeling Techniques and Their Effect on the Seismic Response of a Highly Skewed Multi-span Bridge written by James D. Kelley and published by . This book was released on 2005 with total page 1416 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Short and Long-term Performance of a Skewed Integral Abutment Prestressed Concrete Bridge by : Rami Ameer Bahjat
Download or read book Short and Long-term Performance of a Skewed Integral Abutment Prestressed Concrete Bridge written by Rami Ameer Bahjat and published by . This book was released on 2014 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study presents the behavior of a precast skewed integral abutment bridge (IAB) using the recently developed NEXT-F Beam section in particular. In order to understand the bridge response, a 3-dimensional finite element model of a bridge (Brimfield Bridge) was developed to examine the thermal effect on the response of the bridge structural components. Eighteen months of field monitoring including abutments displacements, abutment rotations, deck strains, and beam strains was conducted utilizing 136 strain gauges, 6 crackmeters, and 2 tiltmeters. The behavior of the NEXT beams during construction was examined by conducting hand calculation considering all factors that could affect strain readings captured by strain gauges embedded in the 6 beams. Parametric analysis and model validation were conducted considering the effect of soil conditions, distribution of thermal loads, and the coefficient of thermal expansion used for the analyses. Using the validated model, the effect pile orientation was investigated. All the results and illustration plots are presented in detail in this study. As a result of this study, the behavior of the NEXT beams during construction was explained. Long term behavior of the bridge was also explained using field data and FE model. Furthermore, it was concluded that the coefficient of thermal expansion of concrete and temperature variation along the bridge depth and transverse direction can have a significant effect on the strain readings and calculated response, respectively. Lastly, it was found that orienting piles with their web perpendicular on the bridge centerline or with their web perpendicular to the abutment centerline will result in small ratio of moment demand to moment capacity.
Book Synopsis Sensitivity Analysis of Skewed Bridges Response to Earthquake Excitation by : Hoda Emami
Download or read book Sensitivity Analysis of Skewed Bridges Response to Earthquake Excitation written by Hoda Emami and published by . This book was released on 2009 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Experimental and Analytical Investigation of Seismic Bridge-abutment Interaction in a Curved Highway Bridge by : Joseph Wieser
Download or read book Experimental and Analytical Investigation of Seismic Bridge-abutment Interaction in a Curved Highway Bridge written by Joseph Wieser and published by . This book was released on 2014 with total page 1040 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seat-type bridge abutments are most commonly used to support the end spans of curved highway bridges. This type of abutment is often selected to eliminate unbalanced stresses in the superstructure under service loads, in particular thermal expansion and contraction. However, depending on the width of the expansion gap, large earthquakes may cause the expansion gap to close which results in bridge-abutment interaction. This phenomenon was studied in a federally-funded research project examining the seismic performance of curved highway bridges at the University of Nevada, Reno. As a part of this research a 2/5 th scale model of a 3-span curved steel girder bridge was constructed on four multi-degree-of-freedom shake tables. Two configurations of the bridge one without bridge-abutment interaction and one with nonlinear bridge-abutment interaction were tested. The purpose of these tests was to: (i) identify the influence of bridge-abutment interaction on the global seismic response of the bridge, (ii) characterize the force-deformation characteristics of dynamic bridge-abutment interaction, and (iii) provide experimental data used to calibrate numerical models of bridges including bridge abutment interaction. Based on the experimental investigation it was concluded that bridge-abutment interaction shortens the effective period of vibration of the bridge, which results in decreased deck displacement and increased total base shear demands. However, the increase in base shear demand is resisted by the abutments which results in a net reduction in column shear demand. Though the deck displacement is reduced at the mid-span of the bridge, the active displacement of the deck at the abutments is increased due to the increased in-plane deck rotation generated as a result of the sudden changes in eccentricity between the center of mass and center of stiffness. The amount of in-plane rotation is shown to depend on the phasing and intensity of the ground motion. Interaction between the bridge and abutment backwall can generate significant radial shear forces through contact friction. These radial forces limit the radial displacement of the bridge while in contact with the backwall particularly after the radial shear keys have failed. However, depending on the details of the abutment backwall local damage may occur. In general, engaging the passive resistance of the backfill soil was able to improve the seismic response of the bridge by reducing damage to the columns and adding an additional form of energy dissipation. Both rigorous 3D finite element and simplified grillage models of the experimental model were validated using available software. Good agreement between the numerical models and the experimental data were obtained using both models however the computational effort was greatly reduced using the simplified grillage model. A grossly simplified 3DOF model of the bridge analyzed using the linear multi-modal response spectrum method was shown to give a prediction of the peak displacement response with minimal complexity. Finally, a parameter study determined that the degree of curvature, size of expansion gap, column diameter, and abutment backfill soil type all influence the response of the bridge. Based on the small scale parameter study conducted herein, bridge designers are encouraged to optimize the combination of expansion gap width with the selection of column diameter to minimize the column and/or abutment soil ductility demands.
Book Synopsis Performance-based Seismic Assessment of Skewed Bridges with and Without Considering Soil-structure Interaction Effects for Various Site Classes by : Abdoulreza Ghotbi
Download or read book Performance-based Seismic Assessment of Skewed Bridges with and Without Considering Soil-structure Interaction Effects for Various Site Classes written by Abdoulreza Ghotbi and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This study aims to investigate the behavior of skewed and straight highway overpass bridges both with and without taking into account the effects of Soil-Structure Interaction (SSI) due to near-fault ground motions. Both deterministic (i.e., pushover and nonlinear dynamic analyses) and probabilistic approaches were utilized. A set of response sensitivity analyses was performed considering various skew angles, column elements, and soil properties for bridge considered both as fixed-base and SSI models. It has been observed that as the skew angle increased, the bridge responded more severely to the ground motion. For instance, the deck rotation and shear-keys displacement increased with an increase in the skew angle. A modal pushover analysis was also performed in conjunction with the nonlinear dynamic analysis. It has been found that combining the bridge responses for various modes of vibration resulted in a relatively accurate seismic response compared to the nonlinear dynamic analysis while saving time and analysis cost, to a great extent. A probabilistic analysis was also performed considering record-to-record variability in ground motion, and a set of probabilistic seismic demand and fragility plots was generated. The effects of change in the skew angle and also SSI were studied to see various bridge responses. The damage probability increased especially with respect to deck rotation as the skew angle increased. The SSI had a decreasing effect on the overall response of the bridge with pile foundation.
Book Synopsis Destructive Testing and Ultimate Capacity of Skewed Simple-span Bridges by : Andrew J. Bechtel
Download or read book Destructive Testing and Ultimate Capacity of Skewed Simple-span Bridges written by Andrew J. Bechtel and published by ProQuest. This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to advances in computing in the late 20 th century, it is now possible to create three-dimension nonlinear analytical models of structures. These models provide the capability of modeling the system as a whole and can lead to more accurate predictions of the system's ultimate capacity. Before these three-dimensional modeling techniques can become common place design tools, the accuracy of the models must be verified by comparing their modeling results to data from full-scale experiments in which structural systems are loaded to failure. To add to the engineering community's knowledge of the ultimate capacity of bridges, the University of Delaware and the Delaware River Bridge Authority have plans to perform destructive testing of a single span simply-supported skewed bridge (Bridge 7R). In preparations for the destructive test, three-dimensional non-linear finite element (FE) models were created to predict the ultimate capacity of the bridge (Ross, 2007). In order to evaluate the performance of existing FE models, a 1/5-scale model bridge was constructed and tested to its ultimate capacity. The results of the test showed that the assumption of a linear elastic concrete deck gave the FE model a greater stiffness and ultimate capacity. In order to predict the ultimate capacity, an advanced concrete model that allows for deterioration must be implemented. A unique aspect of Bridge 7R is that its supports are skewed in excess of 60 degrees. This provides a unique opportunity to observe how skew effects influence the ultimate capacity of the structure. To investigate the effects of skew on bridge performance, a parametric study using FE models was also performed. The results of the study showed that the ultimate capacity of a bridge increases as skew increases. Also, the reaction forces at the obtuse corners increase with increased skew. These phenomena occur due to the difference in stiffness across the width of the bridge at the supports.
Book Synopsis Effect of Abutment Skew and Horizontally Curved Alignment on Bridge Reaction Forces by : Lucas Richard Miner
Download or read book Effect of Abutment Skew and Horizontally Curved Alignment on Bridge Reaction Forces written by Lucas Richard Miner and published by . This book was released on 2014 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents analysis results from a parametric study investigating the effects of abutment skew and horizontal alignment curvature on bridge reaction forces. Over 800 single-span box girder bridges were modeled using three-dimensional finite element analysis software. The effects of skew angle, curve angle, and a coupled skew-curve effect on abutment reactions in the obtuse corners of single-span box girder bridges were found to be significant. These results are compared with state-of-the-art bridge design practice and LRFD Specification procedures that provide guidance on designing bridges with skew and horizontal curvature. Interestingly, the results demonstrate that the obtuse corner reaction forces are greatly influence by the bridge aspect ratio across a wide variety of skew and curve angles. Furthermore, the horizontal alignment curvature has a large effect, even at very small alignment central angles. Moreover, the effect of skew angle is shown to be partially dependent on bridge curvature; although this coupling of the skew and curve effects is minimal at small skew angles. The bearing stiffness was also varied, which had a large effect on the reactions of skewed and curved bridges. Empirical equations for skew and curve correction are proposed and additional research recommended in the summary chapter.
Book Synopsis The Integration of Experimental and Simulation Data in the Study of Reinforced Concrete Bridge Systems Including Soil-foundation-structure Interaction by : Glenn Matthew Dryden
Download or read book The Integration of Experimental and Simulation Data in the Study of Reinforced Concrete Bridge Systems Including Soil-foundation-structure Interaction written by Glenn Matthew Dryden and published by . This book was released on 2009 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt:
