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Author: Syed Ali Publisher: LAP Lambert Academic Publishing ISBN: 9783659546198 Category : Languages : en Pages : 308
Book Description
Field studies were carried out to investigate various parameters of bridges found in northern part of Pakistan. After the Kashmir earthquake of Mw7.6 in 2005, detailed field investigations of seismic performance of bridges was undertaken. A mathematical function to define the functionality of bridges was developed which is helpful for quantifying the seismic resilience of bridges. Criterion for minimum required functionality for different bridges and limit states were defined for large rare earthquake and for moderate occasional earthquakes. From the field data, a series of experimental studies were undertaken on scaled models representing typical bridge pier of low concrete strength having single solid circular section. The experimental results of hysteresis and dynamic characteristics are used to establish expected prototype bridge columns. Detailed numerical studies were undertaken in which inelastic nonlinear dynamic analyses were carried out on calibrated numerical model. Period based response modification factors are established. This research is sponsored by Higher Education Commission of Pakistan & facilitated by University of Engineering & Technology Peshawar.
Author: Syed Ali Publisher: LAP Lambert Academic Publishing ISBN: 9783659546198 Category : Languages : en Pages : 308
Book Description
Field studies were carried out to investigate various parameters of bridges found in northern part of Pakistan. After the Kashmir earthquake of Mw7.6 in 2005, detailed field investigations of seismic performance of bridges was undertaken. A mathematical function to define the functionality of bridges was developed which is helpful for quantifying the seismic resilience of bridges. Criterion for minimum required functionality for different bridges and limit states were defined for large rare earthquake and for moderate occasional earthquakes. From the field data, a series of experimental studies were undertaken on scaled models representing typical bridge pier of low concrete strength having single solid circular section. The experimental results of hysteresis and dynamic characteristics are used to establish expected prototype bridge columns. Detailed numerical studies were undertaken in which inelastic nonlinear dynamic analyses were carried out on calibrated numerical model. Period based response modification factors are established. This research is sponsored by Higher Education Commission of Pakistan & facilitated by University of Engineering & Technology Peshawar.
Author: Gilberto Axel Chang Publisher: ISBN: Category : Columns, Concrete Languages : en Pages :
Book Description
Concerned with computational modeling of energy absorption (fatigue) capacity of reinforced concrete bridge columns by using a cyclic dynamic fiber element model.
Author: Sean McGuiness Publisher: ISBN: Category : Bridges Languages : en Pages : 139
Book Description
Research on seismic retrofitting of Reinforced Concrete (RC) bridge columns in the United States (U.S.) was motivated by damage observed following the 1971 San Fernando, 1989 Loma Prieta, and 1994 Northridge earthquakes of California. The research resulted in a retrofitting procedure that consisted of installing steel jackets around RC bridge columns to enhance the lateral deformation capacity. Although the research focused on the development of this retrofit strategy for bridge columns in California, the Washington State Department of Transportation (WSDOT) implemented the program in 1991. Unlike the strike-slip faults in California, seismicity in western Washington is generally dominated by the Cascadia Subduction Zone fault. The 1964 Alaska, U.S., 2010 Maule, Chile and 2011 Tohoku, Japan are examples of mega-thrust long duration earthquakes emanating from a subduction zone fault and producing ground motions with longer durations of strong shaking than strike-slip faults. The research conducted in this study was motivated by the need to assess performance of the existing retrofit strategy when subjected to the expected demands of subduction zone earthquakes. The research conducted herein was an experimental study on the behavior of steel jacket retrofitted bridge columns subjected to demands from long duration earthquakes. Six reduced scale column specimens were designed, constructed, and tested as cantilevers. WSDOT's inventory was characterized to inform the values used for the column parameters, such that the six columns were intended to reasonably cover the range of values for critical parameters. Five of six tests utilized a modified fully reversed-cyclic lateral loading protocol to include additional cycles characteristic of long duration earthquakes. The sixth test used an earthquake protocol, obtained from the response of a single degree of freedom model to a synthetic Cascadia Subduction Zone ground motion in western Washington. Study results indicated stable drifts, including minimal pinching in the load-displacement response indicative of favorable hysteretic energy dissipation, at drifts in excess of the 4\\% expectation set forth in the steel jacket retrofit design guidelines. Total deformation was primarily a result of longitudinal reinforcement bond slip and elongation at the footing-column interface with strength degradation due to low-cycle fatigue fracture.
Author: Suriya Prakash Shanmugam Publisher: ISBN: Category : Bridges Languages : en Pages : 634
Book Description
"Reinforced concrete (RC) columns of skewed and curved bridges with unequal spans and column heights can be subjected to combined loading including axial, flexure, shear, and torsion loads during earthquakes. The combination of axial loads, shear force, and flexural and torsional moments can result in complex failure modes of RC bridge columns. This study carried out experimental and analytical studies to investigate the seismic performance of circular RC columns under combined loading including torsion. The main variables considered here were (i) the ratio of torsion-to-bending moment (T/M), (ii) the ratio of bending moment-to-shear (M/V) or shear span (H/D), and (iii) the level of detailing for high and moderate seismicity (high or low spiral ratio). In particular, the effects of the spiral reinforcement ratio and shear span on strength and ductility of circular RC columns under combined loading were addressed. In addition, the effects of torsional loading on the bending moment-curvature, ductility, and energy dissipation characteristics were also considered. The analytical investigation examined the development of existing models for flexure and pure torsion. Interaction diagrams between bending, shear and torsional loads were established from a semi-empirical approach. A damage-based design approach for circular RC columns under combined loads was proposed by decoupling damage index models for flexure and torsion. Experimental and analytical results showed that the progression of damage was amplified by an increase in torsional moment. An increase in the transverse spiral reinforcement ratio delayed the progression of damage and changed the torsional-dominated behavior to flexural-dominated behavior under combined flexural and torsional moments"--Abstract, leaf iii.
Author: Yang Yang Publisher: ISBN: Category : Columns, Concrete Languages : en Pages : 458
Book Description
"During earthquakes, reinforced concrete (RC) bridge columns may experience different levels of damage such as cracking, spalling, or crushing of concrete and yielding, buckling, or fracture of reinforcing bars. This study developed and assessed permanent and emergency methods to repair damaged bridge columns with fractured longitudinal reinforcement through experimental and modeling work. The permanent repair method involved replacement of the plastic hinge region by removal of spirals, replacement of longitudinal bar segments by mechanically splicing with new bars segments attached with mechanical couplers, replacement of concrete, and installation of an externally bonded carbon fiber reinforced polymer (CFRP) jacket. The emergency repair method involved removal of damaged concrete, bonding and embedding CFRP strips for flexural reinforcement, building a jacket from a prefabricated CFRP laminate, and repair of the footing with CFRP fabric. The repair methods were evaluated by large-scale component tests on RC column specimens subjected to constant axial loading and slow cyclic loading resulting in combined flexure, shear, and torsion. Test results showed that the repair methods developed in this study are capable of restoring the seismic performance of the repaired columns to that of the undamaged columns in terms of lateral load and deformation capacity, as well as torsional load and twist capacity. However, both repair methods resulted in lower lateral and torsional stiffness as well as lower energy dissipation capacity. Three-dimensional truss models were developed to simulate the as-built and repaired columns and showed efficiency and accuracy in predicting the response of columns under combined cyclic loading including torsion"--Abstract, page iii.
Author: Tim B. Link Publisher: ISBN: Category : Columns, Concrete Languages : en Pages : 73
Book Description
The research presented in this thesis assessed the use of high strength steel (HSS) reinforcement for use in reinforced concrete (RC) bridge columns. HSS is not currently allowed in reinforced concrete bridge columns due to a lack of information on the material characteristics and performance information when used in RC bridge columns. Potential benefits in construction, performance, and economics justify the need for research. This research investigated the performance of HSS (ASTM A706 Grade 80 reinforcement) embedded in half-scale RC bridge columns. Column design followed standard design methodologies used by federal and state highway agencies. Six columns were subjected to lateral cyclic loadings, three columns were constructed with Grade 60 reinforcement and three columns were constructed with Grade 80 reinforcement. Results indicate that the columns constructed with Grade 80 reinforcement achieved similar resistances and displacement ductility values when compared with the reference columns constructed with Grade 60 reinforcement. The columns constructed with Grade 60 reinforcement showed larger hysteretic energy dissipation and typically exhbitied larger curvature ductility values than the columns constructed with Grade 80 reinforcement. The effects of the longitudinal reinforcement ratio and moment-shear span ratio on column performance were similar between columns constructed with Grade 60 reinforcement and columns constructed with Grade 80 reinforcement. The results from this research present a promising step towards the implementation of Grade 80 reinforcement in the design and construction of RC bridge columns, within the bounds of the variables used in the testing program.
Author: Syed Ali
Author: Syed Ali
Author: Gilberto Axel Chang
Author: Sean McGuiness
Author: Dawn Ellen Lehman
Author: Mahmoud Mohamad Hachem
Author: Sarira Motaref
Author: Suriya Prakash Shanmugam
Author: Gilberto Axel Chang
Author: Yang Yang
Author: Tim B. Link