Download or read book Seismic Response of a Hybrid Fiber reinforced Concrete Bridge Column Detailed for Accelerated Bridge Construction written by Wilson Nguyen and published by . This book was released on 2014 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Earthquake Resilient Bridge Columns Utilizing Damage Resistant Hybrid Fiber Reinforced Concrete written by William Dean Trono and published by . This book was released on 2014 with total page 199 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modern reinforced concrete bridges are designed to avoid collapse and to prevent loss of life during earthquakes. To meet these objectives, bridge columns are typically detailed to form ductile plastic hinges when large displacements occur. California seismic design criteria acknowledges that damage such as concrete cover spalling and reinforcing bar yielding may occur in columns during a design-level earthquake. The seismic resilience of bridge columns can be improved through the use of a damage resistant hybrid fiber reinforced concrete (HyFRC). Fibers delay crack propagation and prevent spalling under extreme loading conditions, and the material resists many typical concrete deterioration mechanisms through multi-scale crack control. Little is known about the response of the material when combined with conventional reinforcing bars. Therefore, experimental testing was conducted to evaluate such behaviors. One area of focus was the compression response of HyFRC when confined by steel spirals. A second focus was the tensile response of rebar embedded in HyFRC. Bridge columns built with HyFRC would be expected to experience both of these loading conditions during earthquakes. The third focus of this dissertation was the design, modeling, and testing of an innovative damage resistant HyFRC bridge column. The column was designed to rock about its foundation during earthquakes and to return to its original position thereafter. In addition to HyFRC, it was designed with unbonded post-tensioning, unbonded rebar, and headed rebar which terminated at the rocking plane. Because of these novel details, the column was not expected to incur damage or residual displacements under earthquake demands exceeding the design level for ordinary California bridges. A sequence of scaled, three dimensional ground motion records was applied to the damage resistant column on a shaking table. An equal scale reinforced concrete reference column with conventional design details was subjected to the same motions for direct comparison. Compression tests showed that the ductility of HyFRC is superior to concrete in the post-peak softening branch of the response. HyFRC achieved a stable softening response and had significant residual load capacity even without spiral confinement. Concrete required the highest tested levels of confinement to achieved comparable post-peak ductility. Tension tests showed that HyFRC provides a substantial strength enhancement to rebar well beyond their yield point. Interesting crack localization behavior was observed in HyFRC specimens and appeared to be dependent on the volumetric ratio of rebar. The damage resistant HyFRC bridge column attained its design objectives during experimental testing. It exhibited pronounced reentering behavior with only light damage under earthquake demands 1.5 to 2.0 times the design level. It accumulated only 0.4% residual drift ratio after seven successive ground motions which caused a peak drift ratio of 8.0%. The conventional reinforced concrete column experienced flexural plastic hinging with extensive spalling during the same seven motions. It accumulated 6.8% residual drift ratio after enduring a peak drift ratio of 10.8%.

Download or read book A Pre tensioned Bent System for Accelerated Bridge Construction in Seismic Regions written by Ólafur Sveinn Haraldsson and published by . This book was released on 2015 with total page 327 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nearly all bridge bents (intermediate supports) are constructed of cast-in-place reinforced concrete. Such bridges have served the nation well in the past, but to meet current design expectations, they need to be improved in three areas: 1) speed of construction, 2) seismic resiliency, and 3) durability. Building on previous research at the University of Washington (Hieber et al. 2005, Wacker et al. 2005, Pang et al. 2010, and Haraldsson et al. 2013), a new pre-tensioned bent system has been developed to address these needs. The system consists of 1) precast technology that reduces construction time, 2) unbonded pre-tensioning that minimizes post-earthquake displacements, and 3) high-performance materials that extend the bridge's life-span. Davis et al. (2012) tested a version of the system using conventional concrete in the plastic hinge regions. They found that pre-tensioning improved the system's re-centering capabilities but led to earlier bar buckling and bar fracture than in previously tested RC columns. In order to delay bar buckling and bar fracture, the system was modified to include Hybrid Fiber Reinforced Concrete (HyFRC) in the plastic hinge regions. This composite concrete has been shown to exhibit superior durability and cracking resistance (Ostertag et al. 2007). The effect of the HyFRC on the pre-tensioned bent system was investigated both with quasi-static and dynamic tests. The quasi-static tests showed that using HyFRC in the plastic hinge region increased column ductility; in all cases the column maintained more than 80% of its strength up to a drift ratio of 10%. The HyFRC also delayed spalling of the concrete, but it did not significantly increase the drift ratios at the onset of bar buckling and bar fracture. The shake-table tests of a cantilever column, which was designed to re-center up to a drift ratio of 3.0%, showed that the new system had lower expected residual drifts than columns constructed with conventional cast-in place methods. The pre-tensioned column had a residual drift of 0.23% after experiencing a peak drift ratio of 5.5%. In contrast, the companion reference column, constructed using cast-in-place technology, had a residual drift ratio of 0.83% after experiencing a peak drift ratio of 5.7%. A numerical model in OpenSees was developed and calibrated with a set of 34 RC quasi-static, cyclic tests. This model was calibrated using a concrete constitutive model that takes into account concrete early reloading, developed as part of this research, and used commonly used steel constitutive models; Giuffre-Menegotto-Pinto's (Steel02) model, and Moehle and Kunnath's (ReinforcingSteel) model. The simulations showed improved accuracy in comparison to previous research (e.g., Berry and Eberhard 2007), and showed that the response of the system was affected more by the chosen steel model than by the concrete model. The results of these simulations were used to make predictions of the response of five columns tested on the UC Berkeley shake table. These simulations showed that models built using the proposed strategy predict peak displacements quite accurately, especially at the yield and design level, but do not accurately capture residual displacements.

Download or read book Seismic Response of Precast Bridge Columns with Energy Dissipating Joints written by Sarira Motaref and published by . This book was released on 2011 with total page 707 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Application of Accelerated Bridge Construction Connections in Moderate to High Seismic Regions written by and published by Transportation Research Board. This book was released on 2011 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: TRB’s National Cooperative Highway Research Program (NCHRP) Report 698: Application of Accelerated Bridge Construction Connections in Moderate-to-High Seismic Regions evaluates the performance of connection details for bridge members in accelerated bridge construction in medium-to-high seismic regions and offers suggestions for further research.

Download or read book Self Compacting Hybrid Fiber Reinforced Concrete Composites for Bridge Columns written by Pardeep Kumar and published by . This book was released on 2011 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Seismic Response of Concrete Bridges written by Kosalram Krishnan and published by . This book was released on 1999 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Precast Column footing Connections for Accelerated Bridge Construction in Seismic Zones written by Zachary Benjamin Haber and published by . This book was released on 2013 with total page 1224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Accelerated bridge construction (ABC) has become increasingly popular in the eyes of state and federal transportation agencies because of its numerous advantages. To effectively execute ABC projects, designers utilize prefabricated structural elements that can be quickly assembled to form functional structural systems. It is advantageous to the bridge designer if these systems emulate the design and behavior of conventional cast-in-place systems. If this can be achieved, typical analysis and design procedures can be used. The difficulty with developing emulative systems is usually encountered in the design and detailing of connections. Substructure connections are particularly critical in seismic zones because they must dissipate energy through significant cyclic nonlinear deformations while maintaining their capacity and the integrity of the structural system. The research presented in this dissertation focused on developing and evaluating earthquake resistant connections for use in accelerated bridge construction. The project was comprised of three main components; testing of five large-scale precast reinforced concrete column models, a series of individual component tests on mechanical reinforcing bar splices, and extensive analytical studies. Column studies included the design and construction of five half-scale bridge column models that were tested under reversed slow cyclic loading. Four new moment connections for precast column-footing joints were developed each utilizing mechanical reinforcing bar splices to create connectivity with reinforcing bars in a cast-in-place footing. Two different mechanical splices were studied: an upset headed coupler and grout-filled sleeve coupler. Along with the splice type, the location of splices within the plastic hinge zone was also a test variable. All column models were designed to emulate conventional cast-in-place construction thus were compared to a conventional cast-in-place test model. Results indicate that the new connections are promising and duplicate the behavior of conventional cast-in-place construction with respect to key response parameters. However, it was discovered that the plastic hinge mechanism can be significantly affected by the presence of splices and result in reduced displacement ductility capacity. In order to better understand the behavior of mechanical splices, a series of uniaxial tests were completed on mechanically-spliced reinforcing bars under different loading configurations: monotonic static tension, dynamic tension, and slow cyclic loading. Results from this portion of the project also aided the development of analytical models for the half- and prototype-scale column models. Results indicated that, regardless of loading configuration, specimens failed by bar rupture without damage to the splice itself. The analytical studies conducted using OpenSEES included development of microscope models for the two mechanical reinforcing bars splices and full analytical models of the five half-scale columns, which were both compared with respective experimental results to validate the modeling procedures and assumptions. Prototype-scale analytical models were also developed to conduct parametric studies investigating the sensitivity of the newly developed ABC connections to changes in design details. In general, the results of this study indicate that the newly develop ABC connections, which utilize mechanically-spliced connections, are suitable for moderate and high seismic regions. However, emulative design approaches are not suitable for all of the connections develop. A set of design recommendations are provided to guide bridge engineers in the analysis and design of these new connections.

Download or read book Design and Evaluation of Reinforced Concrete Bridges for Seismic Resistance written by Mark Aschheim and published by . This book was released on 1997 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this report, seismic design approaches for reinforced concrete bridges are reviewed and uncertainties in seismic design and evaluation are discussed. The modeling of bridge components and systems is discussed, and analytical studies of the response series of simple bridges are made. The relative utility of several design approaches and stiffness assumptions for controlling seismic demands is assessed. Modeling of column and wall pier flexural and shear strengths is examined in detail, and available models for the inelastic shear strength of columns are compared with test data.

Download or read book Unbonded Pre tensioned Bridge Columns with Hybrid Fiber reinforced Concrete Shells written by Gunnsteinn Finnsson and published by . This book was released on 2013 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many bridges in the United States are getting old and will need to be replaced in the near future. If these bridges are constructed with conventional cast-in-place methods, this construction will cause traffic congestion, which is a costly problem. Furthermore, these cast-in-place systems are susceptible to earthquake-induced damage, such as bar buckling, bar fracture and residual displacements. A new pre-tensioned precast bent system has been developed to meet these challenges. The system consists of precast technology to accelerate the bridge construction, unbonded pre-tensioning to minimize residual displacements, and high-performance materials that extend the bridge durability. Davis et al. (2012) tested the new system using only conventional concrete. They found out that pre-tensioning improves system's re-centering capabilities, but it results in earlier bar buckling and bar fracture than in previously tested reinforced concrete columns (Pang et al. 2008, Haraldsson et al. 2012). Two columns were designed and tested in the University of Washington Structural Laboratory. In the plastic-hinge region of the columns a very ductile concrete shell was added. The shell was made of a hybrid fiber reinforced concrete (HyFRC, developed by Prof. Ostertag at U.C. Berkeley) containing both polymer and steel fibers. The main goal of adding the shell was to delay spalling and buckling of the longitudinal reinforcement bars. One of the columns was the same as one of the columns tested by Davis with only the addition of HyFRC shell. The other column had a HyFRC shell in the plastic hinge region and stainless steel reinforcement bars as longitudinal reinforcement instead of regular black steel rebars. The addition of the stainless steel rebar was expected to increase the ductility of the system and minimize the corrosion susceptibility. The tests showed that the HyFRC delayed the concrete spalling, and to a limited extent, the buckling of the longitudinal bars. The main benefits of having the HyFRC shell was that the columns kept 80% of its strength at 10% drift ratio, which was much higher than the conventional concrete specimens tested by Davis et al. (2012). The response of the stainless steel column was comparable to the black steel column, the main difference being that the stainless steel column was stronger, because the stainless steel was stronger than the black steel.

Download or read book Next Generation of Bridge Columns for Accelerated Bridge Construction in High Seismic Zones written by Mostafa Tazarv and published by . This book was released on 2014 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt: Longitudinal bar debonding allowed spread of yielding and prevented premature failure of reinforcements in UHPC-filled duct connections and grouted coupler column pedestal. The SMA-reinforced ECC column showed superior seismic performance compared to a conventional column in which the plastic hinge damage was limited to only ECC cover spalling even under 12% drift ratio cycles. The column residual displacements were 79% lower than CIP residual displacements on average due to the superelastic NiTi SMA longitudinal reinforcement, and higher base shear capacity and higher displacement capacity were observed. The analytical modeling methods were simple and sufficiently accurate for general design and analyses of precast components proposed in the present study. The proposed symmetrical material model for reinforcing NiTi superelastic SMA was found to be a viable alternative to the more complex asymmetrical model.

Download or read book Seismic Behavior and Retrofit of Older Reinforced Concrete Bridge T joints written by Laura N. Lowes and published by . This book was released on 1995 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: A series of experimental tests investigating the seismic response of reinforced concrete beam-column T-joints was recently completed at the University of California, Berkeley. The evaluated connection was representative of an interior beam- column joint from a multi-column bridge frame built in the late 1950's. Three one-third scale models, representing the as-built connection and two retrofit connections, were tested. The results of this research project are an improved understanding of the seismic behavior of lightly reinforced bridge T-joints as well as verification of a design procedure for retrofitting this type of connection.

Download or read book Repair and Testing of Out of Plane Seismic Response of Pocket Connection written by and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Accelerated bridge construction (ABC) has been utilized in precast bridge structures because of its advantage to expedite onsite construction. In ABC, one of the main concerns is the joint connection as it needs to be well designed to maintain structural integrity. Several studies were able to demonstrate the effectiveness of ABC pocket connections for partial and fully precast columns. The pocket connections are designed to have the cap beam longitudinal reinforcements bundled outside the joint allowing the placement of the column uninhibited. On the contrary, this has been an issue for cast-in-place (CIP) construction where congestion of the reinforcements in the joint regions is typical. A recent study at the University of Nevada, Reno (UNR) was conducted by utilizing ABC pocket connection in CIP bridges. The specimen was tested at UNR Earthquake Engineering Laboratory on a shake table in an upside-down configuration using an increasing scaled ground motion. The specimen performed well under out-of-plane ground motion excitations and the ductility of the column was confirmed through typical plastic hinge behavior. In this study, the main objective is to further use the specimen from the recent UNR test to repair the damaged column and to test the repaired specimen using the same loading protocol as the original model. The objective was achieved by developing a repair method using flush cutting and coring of the damaged column. A new column was constructed using the exact reinforcements as the original model. However, the column was cast monolithically in the pocket joint as opposed to the original model where the column reinforcement sat in two different concrete casts with a cold joint at the column-cap beam interface. The repaired column was subjected to the same loading protocol as the original model using the scaled 1994 Northridge earthquake ground motion recorded at the Sylmar Converter Station. The repaired specimen performed well as the plastic hinge zone developed in the column outside the joint, close to the interface of the cap beam, as desired and required by design. The results were compared to the original specimen and the maximum drift ratio for 20% through 450% of the earthquake motion was relatively equal. However, for 550% and 650% of the earthquake motions, the drift ratio in the repaired specimen was significantly larger compared to the original specimen. The high drift ratios were attributed to the slippage of the column in the joint and were validated by an increase in the ratios between the rotations of the original and repaired column recorded at the base. The cap beam remained essentially elastic, i.e. capacity-protected as required, throughout the test which is similar to the performance of the original model. Lastly, recommendations for the repair of CIP cap beam-column emulating ABC pocket connection are provided with special attention to roughen the pocket joint connection to develop a sufficient bond between the two members.

Download or read book 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 published by . This book was released on 2014 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Seismic Performance of Bridge Column pile shaft Pin Connections for Application in Accelerated Bridge Construction written by Mehrdad Mehraein and published by . This book was released on 2016 with total page 1468 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bridges with integral superstructures are common in high-seismic regions. The superstructure and substructure are connected using rigid connections in these bridges. However, hinge or “pin” connections may be used to connect columns to pile-shafts to reduce the overall force demand in the integral bridges, leading to smaller and more economical foundations. Additionally, prefabrication of structural elements facilitates accelerated bridge construction (ABC), which could improve the quality and economy of project compared to cast-in-place (CIP). The primary objectives of this research were to investigate the seismic performance of three types of bridge bent connections: (1) pipe-pin connections at column-pile shaft joints for CIP and precast constructions (2) rebar-pin connections at column-pile shaft joint for CIP and precast constructions, and (3) pocket connections to develop rigid joints between precast columns and precast pier caps. This research was comprised of experimental and analytical studies. The experimental portion of the study was conducted on a shake table at the Earthquake Engineering Laboratory at the University of Nevada, Reno including two 1/3.75 scale, two-column bents subjected to seismic loadings. The cap beam in each bent was precast and connected to the columns using pocket details. The pin connections were used to connect the columns to pedestals, which simulated the pile-shafts. The column-pedestal joints were formed using pipe-pins in one bent and rebar-pin in the other bent. The available details of pin connections were modified for utilizing in the bents because the tensile force transfer mechanism and pile-shaft failure modes had not been accounted for in the current practices. A proposed ABC method for pin connections was investigated by constructing one column in each bent as a precast shell filled with self-consolidating concrete (SCC), whereas the other column was CIP. Furthermore, engineered cementitious composite (ECC) was incorporated in one column plastic hinge region of each bent to explore the effects of ECC on the seismic performance of the columns. The shake table experiments confirmed that the proposed design methods meet the safety and performance requirements of the codes under seismic loadings. The analytical studies consisted of: (1) simple stick models for the pin connections that were developed for the bents as design tools, (2) nonlinear finite element (FE) models for the pin connections in OpenSEES that can be utilized for global analysis of bridges with pin connections, and (3) elaborate nonlinear FE models of the bent with pipe-pins using ABAQUS to investigate the microscopic performance and interactions of the components. The analytical models were evaluated based on their correlation with experimental data and were subsequently used in focused parametric studies to address the gaps in the experimental results and provide more insight into the pin behavior under various conditions. Lastly, design procedures and detailing recommendations for column-pile-shaft connections using pipe-pins and rebar-pins were developed and proposed based on the results of the experimental and analytical parametric studies.

Download or read book Seismic Evaluation of Bridge Columns with Energy Dissipating Mechanisms Research overview written by Mehdi Saiidi and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: TRB's National Cooperative Highway Research Program (NCHRP) Research Report 864: Seismic Evaluation of Bridge Columns with Energy Dissipating Mechanisms, Volume 1: Research Overview and Volume 2: Guidelines describes the evaluation of new materials and techniques for design and construction of novel bridge columns meant to improve seismic performance. These techniques include shape memory alloy (SMA), engineered cementitious composite (ECC), fiber-reinforced polymer (FRP), and rocking mechanisms. The guidelines contained in Volume 2 explore a quantitative evaluation method to rate novel columns as well as design and construction methods for SMA-reinforced ECC columns, SMA-reinforced FRP-confined concrete/columns, and FRP-confined hybrid rocking columns. The project explores the behavior of the selected columns and develops proposed design guidelines according to the AASHTO LRFD Bridge Design Specifications and the AASHTO Guide Specifications for LRFD Seismic Bridge Design. Appendices A-I are available online.

Download or read book Seismic Response of Column cap Beam Tee Connections with Cap Beam Prestressing written by Sri Sritharan and published by . This book was released on 1996 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: Concrete bridge joints in California were detailed with no shear reinforcement in the 1950s. The probable consequence of such poor detailing was demonstrated on an as-built tee (interior) joint from the Santa Monica Viaduct in Los Angeles. When a redesign of this joint was considered with the conventional design methods based upon the maximum joint shear forces, it resulted in a considerable amount of joint reinforcement, causing congestion of steel within the joint. This has been identified as a major construction problem in concrete bridge construction. Three redesigns of the prototye joint were sought with the objective of reducing the amount of reinforcing steel within the joint, thereby ensuring constructability. In all three designs, force transfer models were employed in determining the appropriate amount of joint reinforcement rather than using the joint shear forces as the design parameter. When the cap beam was designed with full prestressing, it was also shown that precast construction can be adopted as an alternative to cast-in-place construction for building multi-column concrete bents. The details of the joint design, seismic performance of all three redesigned units and some design recommendations are presented in this report.