Seismic Response Of Unbonded Post Tensioned Precast Concrete Segmental Bridge Columns
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Seismic Response Of Unbonded Post Tensioned Precast Concrete Segmental Bridge Columns
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Author : Joshua Tyler Hewes
language : en
Publisher:
Release Date : 2000
Seismic Response Of Unbonded Post Tensioned Precast Concrete Segmental Bridge Columns written by Joshua Tyler Hewes and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with categories.
Seismic Response Of Precast Bridge Columns With Energy Dissipating Joints
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Author : Sarira Motaref
language : en
Publisher:
Release Date : 2011
Seismic Response Of Precast Bridge Columns With Energy Dissipating Joints written by Sarira Motaref and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Columns, Concrete categories.
Precast Segmental Post Tensioned Concrete Bridge Columns For Seismic Regions
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Author : Yu-Chen Ou
language : en
Publisher:
Release Date : 2007
Precast Segmental Post Tensioned Concrete Bridge Columns For Seismic Regions written by Yu-Chen Ou and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
A simplified analytical model for static pushover analysis and a three-dimensional detailed finite element model for cyclic analysis of the proposed bridge columns are developed in this research. In addition, a stiffness degrading hysteretic model is proposed for response-history analysis. With the analytical models, a parametric study is conducted to examine the seismic performance of the proposed columns with different design parameters.
Seismic Analysis And Design Of Precast Concrete Segmental Bridges
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Author : Petros Sideris
language : en
Publisher:
Release Date : 2012
Seismic Analysis And Design Of Precast Concrete Segmental Bridges written by Petros Sideris and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
In this dissertation, the concept of hybrid sliding-rocking (HSR) precast concrete post-tensioned segmental members for seismic applications in bridges is introduced and investigated experimentally and numerically. The HSR members lie into the framework of accelerated bridge construction techniques (ABC) and are primarily intended for applications in moderate and high seismicity areas. The HSR members combine two fundamental components, namely the HSR segmental joints, and the internal unbonded post-tensioning. The HSR joints utilize relative segment-to-segment sliding (joint sliding) and gap opening (joint rocking) to mitigate the applied seismic loading. Joint sliding offers high energy dissipation with minor structural damage as well as moderate self-centering. On the other hand, joint rocking offers low energy dissipation and high self-centering capabilities that deteriorate at larger rocking rotations due to the resulting concrete crushing.^The response of HSR joints is affected by the geometry of the post-tensioning (PT) system along the member length. Hence, linear or nonlinear PT geometry may be used to control joint and member response properties. Two distinct types of HSR members were further studied: (i) HSR members with slip-dominant joints and linear PT geometry (abbreviated as HSR-SD members), and (ii) HSR members with rocking- dominant joints and nonlinear PT geometry (abbreviated as HSR-RD members). The concept of HSR bridges was evaluated through a two-stage experimental study. The first stage included shake table testing of a large-scale (~ 1:2. 39) single-span bridge specimen incorporating a HSR-RD superstructure and two HSR-SD single-column piers. Nearly 150 seismic tests were conducted including far-field and near-fault input motions scaled to different seismic hazard levels.^The second stage included quasi-static testing of the HSR-SD piers with a sequence of displacement-controlled loading cycles of increasing amplitude that eventually reached a drift ratio of approximately 15%. The experimental findings from the large-scale seismic and quasi-static testing programs were complemented by two additional experimental studies; one focusing on the identification of the frictional properties of the HSR joint interface, and another investigating the response of the strand-anchor systems (i.e., unbonded monostrands with their anchorage setups at their ends). Numerical predictions for the quasi-static testing were provided by a model of the HSR-SD pier generated with the ABAQUS general-purpose finite element software, while numerical predictions for the seismic testing were provided by a model of the HSR bridge specimen generated in SAP2000. Comparisons between numerical and experimental results are presented.^This dissertation is concluded with an investigation of the response properties of flexibility-based (or force-based) beam-column elements in the presence of softening section constitutive relations. This study identified and explained critical numerical instability problems observed during the development of force-based elements for HSR members.
Seismic Design And Performance Of Precast Concrete Segmental Bridge Columns
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Author : Joshua T. Hewes
language : en
Publisher:
Release Date : 2002
Seismic Design And Performance Of Precast Concrete Segmental Bridge Columns written by Joshua T. Hewes and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with Bridges categories.
Dynamic Properties And Application Of Steel Fiber Reinforced Self Consolidating Concrete To Segmental Bridge Columns In Moderate To High Seismic Regions
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Author : Nasi Zhang
language : en
Publisher:
Release Date : 2014
Dynamic Properties And Application Of Steel Fiber Reinforced Self Consolidating Concrete To Segmental Bridge Columns In Moderate To High Seismic Regions written by Nasi Zhang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
In this dissertation, the application of steel fiber reinforced self-consolidating concrete (SFRSCC) to precast unbonded post-tensioned segmental bridge columns in moderate-to-high seismic regions is evaluated numerically and experimentally. Drop weight impact tests are first conducted on plain concrete and steel fiber reinforced concrete (SFRC). The standard drop test recommended by the American Concrete Institute (ACI) is first conducted and a modification to this standard ACI, which involves visual inspection of first cracking and ultimate failure, is then developed. The Kolmogorov-Smirnov (K-S) test along with fitted normal and lognormal distributions are used to examine the distribution of the number of blows required to cause first cracking and ultimate failure of the concrete. The minimum sample size required to calculate the impact strength of SFRC is determined using equations available in the literature. This sample size is used in the subsequent impact study on SFRSCC specimens. The static and dynamic properties of ten groups of SFRSCC, including one group of self-consolidating concrete (SCC) without steel fibers, are studied and compared. Dramix℗ʼ ZP305, RC-65/35-BN, and RC-80/30-BP steel fiber (glued and hooked end) at a volume of 0. 25%, 0. 5% and 1% are considered in the study. The static properties are calculated using compression tests, split-tension tests and flexural beam tests. The dynamic properties are determined using the modified ACI impact test. A dynamic load sensor is installed underneath the base plate of the impact test machine to measure the relative reaction force history. The recorded reaction forces are used to develop an automated impact test method, which can circumvent visual inspections. Two large-scale (1:3. 37), precast, unbonded and post-tensioned segmental columns, one constructed with SCC and one constructed with SFRSCC (with 0. 5% of ZP305 steel fiber by volume), are tested under cyclic loading. These segmental columns incorporate shear keys at the joints. The backbone force-displacement relationships of the segmental columns are calculated from a pushover model available in the literature. The hysteretic behavior of the segmental columns under cyclic loading is also simulated by a numerical model developed on the OpenSEES platform. A single span, large-scale (1:3. 37) bridge model incorporating SFRSCC segmental columns (with 0. 5% of ZP305 steel fiber by volume) is tested on a shake table. Two types of cap beam-to-superstructure connections are considered for the bridge model: a connection using non-seismic rubber bearing and a fixed connection. The bridge model is tested for far field and near field ground motions along various directions and with increasing peak ground accelerations (PGAs). The evolution of the cumulative damage to the bridge model after each seismic test is evaluated through a system identification involving white noise excitation. A flag-shaped hysteretic model is proposed and validated through the cyclic test results obtained in this research and those available in the literature. The proposed flag-shaped model is used to predict the seismic response of the bridge model. Adding steel fibers to concrete significantly improves its impact strength and ductility. The SFRSCC segmental columns suffered less damage than the SCC columns for the same level of drift. The large-scale bridge model incorporating SFRSCC segmental columns sustained high intensity far field and near field ground motions with limited damage. The proposed flag-shaped hysteretic model can be used to simulate the cyclic behavior of segmental columns, and to provide reasonable estimates of their seismic response under strong ground motions.
Dynamic Response Of Unbonded Post Tensioned Concrete Walls For Seismic Resilient Structures
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Author : Kimberley M. Twigden
language : en
Publisher:
Release Date : 2016
Dynamic Response Of Unbonded Post Tensioned Concrete Walls For Seismic Resilient Structures written by Kimberley M. Twigden and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Concrete walls categories.
The research in this thesis was conducted with the primary aim of advancing the current state of knowledge of unbonded Post-Tensioned (PT) precast concrete rocking walls. Emphasis was placed on systematically investigating both the static and dynamic experimental response of Single Rocking Wall (SRW) and Precast Wall with End Columns (PreWEC) systems. Using the experimental data generated, simple numerical modelling techniques were investigated and the Direct Displacement Based Design (DDBD) process was verified. The experimental programme consisted of component tests on modified energy dissipating Oconnectors and pseudo-static cyclic, snap back, and shake table testing on a selection of SRW and PreWEC systems. The unique experimental investigation into the cyclic response of an improved O-connector confirmed the suitability of the O-connector as a cost effective energy dissipater that is able to demonstrate stable hysteretic behaviour while being easy to install and replace. The focus of the wall tests was on assessing the general wall response and design, the influence of the O-connectors on the wall panel, initial stiffness and fundamental frequency, equivalent viscous damping and residual drifts from different loading types. During the wall tests only minor damage and negligible residual drifts were observed which confirmed the desirable seismic behaviour of SRW and PreWEC systems under both static and dynamic loads. An investigation was performed using a simple single degree of freedom numerical model to provide recommendations on appropriate damping schemes that are able to emulate the seismic response of SRW and PreWEC systems that were validated using the shake table test results. The numerical analyses indicated that good estimation of the seismic response could be attained when using 2% tangent stiffness proportional damping in combination with a hysteretic behaviour calibrated to the cyclic hysteresis. Lastly, an assessment of current methods used for determining the equivalent viscous damping for unbonded PT walls systems in the current DDBD framework was performed. A current method based on the weighted contribution of an unbonded PT only system and a purely dissipative system was found to produce good results when used with the proposed bilinear force-displacement idealisation based on an effective stiffness.
Seismic Response Of Buildings That Utilise Unbonded Post Tensioned Concrete Walls
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Author : Jonathan Watkins (‡c (PhD))
language : en
Publisher:
Release Date : 2017
Seismic Response Of Buildings That Utilise Unbonded Post Tensioned Concrete Walls written by Jonathan Watkins (‡c (PhD)) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with Concrete walls categories.
Unbonded post-tensioned precast concrete walls are a low-damage seismic resisting system that resist lateral loads by rocking at the wall base. This thesis addresses the uncertainty that wall-to-floor interaction can have on the seismic response and performance of buildings that use such wall systems. A computational model was developed and verified to accurately calculate the bi-directional lateral-load response of isolated post-tensioned concrete walls. The wall model was extended to represent a previously tested full scale, four storey building with post-tensioned concrete walls. The building model accurately captured the measured response of the test building that was subjected to increasing intensities of earthquake motion on a tri-directional shake-table. To accurately capture the seismic response of the building the model must represent the in-plane and out-of-plane floor behaviour, account for cracking of the floor, and represent the stiffness of the precast concrete floor units. Wall-to-floor interaction resulted in deformations that were concentrated in the link slab between the wall and adjacent precast floor unit of the test building. This deformation resulted in significant over-strength demands on the wall and column, which the dynamic loading further increased. During the 1995 Kobe earthquake motion the peak wall base shear from the building model was 110% greater compared to the same building model that did not account for wall-to-floor interaction or dynamic loading. A parametric study of the building model found that increasing the rib depth of the precast floor elements or the thickness of the floor resulted in significantly greater over-strength demands compared to the original building. The results of the parametric study confirmed that if the effects of wall-to-floor interaction are not considered as part of the design process, the inelastic mechanisms that develop when a building is subjected to an earthquake may be different than predicted and result in undesirable failure modes An innovative wall-to-floor connector that could eliminate the adverse effects of wall-to-floor interaction was experimentally subjected to the combination of vertical displacement and shear forces they would experience in a major earthquake. Within their design limits the connectors performed well and effectively isolated the floor from the walls vertical displacement while transferring shear force from the floor to the wall.
Advances In Geosynthetics Engineering
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Author : Mohamed Meguid
language : en
Publisher: Springer
Release Date : 2018-10-28
Advances In Geosynthetics Engineering written by Mohamed Meguid and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-10-28 with Science categories.
This volume contains contributions on advances in geosynthetics engineering. Soil reinforcement is a very useful technique to construct several cost-effective soil structures in an environmentally friendly and sustainable manner. The most commonly used reinforcement materials are galvanised steel strips, geosynthetics in the form of woven geotextiles, geogrids and geocomposites, and fibres from natural and waste products. In recent years, there have been advances in the area of soil reinforcement, especially in the utilization of the technique in field projects. The researchers have also been working to understand the behaviour of reinforced soil considering the field challenges of reinforced soil structures. The volume is based on the best contributions to the 2nd GeoMEast International Congress and Exhibition on Sustainable Civil Infrastructures, Egypt 2018 – The official international congress of the Soil-Structure Interaction Group in Egypt (SSIGE).
The Seismic Response Of Precast Segmental Bridge Superstructures With Bonded Tendons
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Author : Marc John Veletzos
language : en
Publisher:
Release Date : 2007
The Seismic Response Of Precast Segmental Bridge Superstructures With Bonded Tendons written by Marc John Veletzos and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with Bridges categories.
Precast segmental construction of bridges can accelerate construction and minimize the cost of bridges in highly congested urban environments, environmentally sensitive regions, difficult to access ravines, and wide river crossings where medium to long repetitive spans are needed. Despite their proven benefits, the use of precast segmental bridges in seismic regions of the United States remains very limited. A main obstacle to their use is concern regarding the seismic response of segment joints. Recent research has shown that segment joints can undergo very large rotations that open up gaps in the superstructure, while maintaining its load carrying capacity, and with little, if any, damage. This dissertation investigates the seismic response of precast segmental bridges using detailed 2D non-linear time-history analyses and focuses on the behavior of segment-to-segment joints constructed using the balanced cantilever method. The joint model was calibrated using results available from experimental work on large scale sub-assemblages. Analytical models of full scale precast segmental bridges with geometries and characteristics, similar to the Otay River Bridge and the San Francisco-Oakland Bay Bridge Skyway in California, were also used in this study. A suite of twenty near field earthquake records was used to determine the median joint response as well as to quantify the effect of vertical motion on the joint response. The earthquake records were scaled using two different scaling methods and the effect on the structure response was studied. Four different pre-earthquake stress conditions were studied to determine if the effects of creep, shrinkage and temperature impact the seismic response of segment joints. In addition, a preliminary investigation into the possibility of removing a portion of the superstructure longitudinal post-tensioning and allowing non-linear elastic response of the segment joints during a significant seismic event was performed. Results indicated that vertical earthquake motions and the pre-earthquake stress-state can alter the response of segment joints. The results also showed that the method of record scaling does not significantly alter the median response, but may effect the variation in response. Furthermore, reducing the longitudinal post-tensioning near the piers may be possible provided that service load cases do not govern the design.