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Seismic Structural Considerations For The Stern And Base Of Retaining Walls Subjected To Earthquake Ground Motions
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Book Synopsis Seismic Structural Considerations for the Stern and Base of Retaining Walls Subjected to Earthquake Ground Motions by :
Download or read book Seismic Structural Considerations for the Stern and Base of Retaining Walls Subjected to Earthquake Ground Motions written by and published by . This book was released on 2005 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cantilever retaining walls can respond externally to earthquake ground motions by sliding or by rotating, or internally by stem wall yielding. The type of response that will have the greatest impact on post-earthquake performance will likely depend on restraint conditions at the base of the wall. Walls founded on soil without an invert slab are most likely to dissipate the inertial energy imposed by earthquake ground motions by sliding. This may also be true for walls founded on fissured or fractured rock. Walls founded on soil or on fissured or fractured rock and prevented by an invert slab from moving laterally are more likely to tip (i.e., rotate) than to slide during a major earthquake event. Walls founded on competent rock without significant joints, faults, or bedding planes and prevented by a strong bond at the rock-footing interface from either translating or rotating are likely to dissipate energy through plastic yielding in the stem wall. All three responses can leave the retaining wall in a permanently displaced condition. The purpose of this report is to provide methodologies for conducting a performance-based earthquake evaluation related to plastic yielding in the stem wall. The methodologies include evaluation of brittle or force-controlled actions and the evaluation of ductile or deformation-controlled actions. The later evaluation provides estimates of permanent (residual) displacement for walls dominated by a stem wall yielding response. Performance-based evaluation methodologies are demonstrated with respect to a wall designed to current Corps ultimate strength design criteria and with respect to an older retaining wall designed to working stress design criteria. Lap splice deficiencies related to older walls are discussed and performance-based evaluation techniques proposed. At present the Corps computer program CWRotate is able to estimate permanent displacements associated with a sliding response and a rotational response.
Book Synopsis Seismic Structural Considerations for the Stem and Base of Retaining Walls Subjected to Earthquake Ground Motions by :
Download or read book Seismic Structural Considerations for the Stem and Base of Retaining Walls Subjected to Earthquake Ground Motions written by and published by . This book was released on 2005 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cantilever retaining walls can respond externally to earthquake ground motions by sliding or by rotating, or internally by stem wall yielding. The type of response that will have the greatest impact on post-earthquake performance will likely depend on restraint conditions at the base of the wall. Walls founded on soil without an invert slab are most likely to dissipate the inertial energy imposed by earthquake ground motions by sliding. This may also be true for walls founded on fissured or fractured rock. Walls founded on soil or on fissured or fractured rock and prevented by an invert slab from moving laterally are more likely to tip (i.e., rotate) than to slide during a major earthquake event. Walls founded on competent rock without significant joints, faults, or bedding planes and prevented by a strong bond at the rock-footing interface from either translating or rotating are likely to dissipate energy through plastic yielding in the stem wall. All three responses can leave the retaining wall in a permanently displaced condition. The purpose of this report is to provide methodologies for conducting a performance-based earthquake evaluation related to plastic yielding in the stem wall. The methodologies include evaluation of brittle or force-controlled actions and the evaluation of ductile or deformation-controlled actions. The later evaluation provides estimates of permanent (residual) displacement for walls dominated by a stem wall yielding response.
Book Synopsis Analysis and Design of Retaining Structures Against Earthquakes by : Shamsher Prakash
Download or read book Analysis and Design of Retaining Structures Against Earthquakes written by Shamsher Prakash and published by . This book was released on 1996 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: GSP 60 contains eight papers on retaining structures to withstand earthquakes presented at sessions of the ASCE National Convention, held in Washington, D.C., November 10-14, 1996.
Book Synopsis Seismic Analysis and Design of Retaining Walls, Buried Structures, Slopes, and Embankments by : Donald G. Anderson
Download or read book Seismic Analysis and Design of Retaining Walls, Buried Structures, Slopes, and Embankments written by Donald G. Anderson and published by Transportation Research Board. This book was released on 2008 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report explores analytical and design methods for the seismic design of retaining walls, buried structures, slopes, and embankments. The Final Report is organized into two volumes. NCHRP Report 611 is Volume 1 of this study. Volume 2, which is only available online, presents the proposed specifications, commentaries, and example problems for the retaining walls, slopes and embankments, and buried structures.
Book Synopsis Effect of Wall-Soil Interface Parameters on Seismic Response of Retaining Walls by : Mohammadhashem Arabzadeh
Download or read book Effect of Wall-Soil Interface Parameters on Seismic Response of Retaining Walls written by Mohammadhashem Arabzadeh and published by . This book was released on 2018 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reinforced soil retaining walls are important public structures. Typically there are two kinds of reinforced soil retaining walls: cantilever retaining walls and Geosynthetic reinforced soil retaining walls. While seismic performance of retaining walls is very important for public safety in the event of an earthquake, there are very limited studies on that. The main objectives of the present thesis are to (i) examine the behavior of the interface between structure and soil under various loading and boundary conditions for RC cantilever retaining walls; (ii) conduct sensitivity study on the seismic response of such walls considering the key parameters such as the cohesion (C), friction angle (z), shear stiffness (Ks), normal stiffness (Kn) and dilation (|); and (iii) study the size (height) effect of the relating walls on the seismic performance of such walls. In order to achieve the above objectives, a baseline model of an RC cantilever retaining wall has been constructed for static and dynamic analysis using the Finite Difference Method (FDM). The data for the baseline model are obtained from a published work on seismic response such a wall subjected to an earthquake in India (1991 Uttarkashi earthquake, 20th October), which used the Finite Element Method (FEM) for analysis. The validated baseline model is then used for an extensive parametric study on the static and dynamic behavior of the system which is not available in the literature. Based on the results of numerical modeling, in the static condition, wall deformation was decreased by increasing the cohesion (C), friction angle (z), shear stiffness (Ks), normal stiffness (Kn) and dilation (|) values. The dynamic behavior of the wall was quite different from the static behavior. With increasing the values of shear strength parameters (Cohesion and friction angle) and also shear stiffness (Ks), the wall displacements increased whereas with increasing normal stiffness (Kn) value, the wall deformation decreased. A sensitivity analysis of wall-soil interface parameters on seismic response of the retaining wall was carried out using the ground motion records from Canada earthquake motion database (6th March, Quebec, 2005) and the results were compared to the Uttarkashi earthquake in India. The results of this comparison showed that the response parameters in terms of the retaining wall deformation are similar for both earthquakes. Moreover, parametric studies on the behavior of the soil retaining walls under Montreal earthquake with three different heights (3 m, 6 m and 9 m), and two different types of soil (clay and sand) and eight input earthquakes motions were performed. Results show that the behavior of wall facing in terms of displacement in both horizontal and vertical direction is different, and the type of soil has a main role in the wall deformation. Finally, a statistical estimation of parameters between soil and retaining wall structure was done. According to this statistical study, cumulative percentage distribution of cohesion (C) and stiffness parameters (shear and normal) against wall deformation were calculated. Then, lower and upper boundary ranges of wall-soil parameters were established for both static and dynamic condition.
Book Synopsis Engineering and Design by : United States. Army. Corps of Engineers
Download or read book Engineering and Design written by United States. Army. Corps of Engineers and published by . This book was released on 1966 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Retaining Structures by : C. R. I. Clayton
Download or read book Retaining Structures written by C. R. I. Clayton and published by Thomas Telford. This book was released on 1993 with total page 854 pages. Available in PDF, EPUB and Kindle. Book excerpt: For practising civil and structural engineers in the field of general earth-retaining structure theory, this work presents the results of many case studies of actual retaining wall analysis, design, and construction. It also includes fundamental papers dealing with the effects of groundwater on passive earth pressure, and other related topics.
Download or read book Engineering and Design written by and published by . This book was released on 1989 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: This manual provides guidance for the safe design and economical construction of retaining and flood walls. This manual is intended primarily for retaining walls which will be subjected to hydraulic loadings such as flowing water, submergence, wave action, and spray, exposure to chemically contaminated atmosphere, and/or severe climatic conditions. For the design of retaining walls which will not be subjected to hydraulic loadings or severe environmental conditions as described above, TM S-8l8-l may be used for computing the loadings and evaluating the stability of the structure.
Book Synopsis Displacement-based Analysis and Design of Rigid Retaining Walls During Earthquakes by : Yingwei Wu
Download or read book Displacement-based Analysis and Design of Rigid Retaining Walls During Earthquakes written by Yingwei Wu and published by . This book was released on 1999 with total page 223 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research focused on the analysis and design of rigid retaining walls subjected to earthquakes and considered nonlinear foundation soil properties. The simultaneous sliding and rocking movements of retaining walls were considered. Seven field conditions, including moist, submerged, perched and saturated backfill with a sloping drain, were specified by design codes. A computer program capable of computing displacement using real time history records or equivalent sinusoidal motions was developed. Finally, a dynamic design procedure was proposed for practicing engineers. The study revealed that maximum shear modulus in foundation soil, maximum ground acceleration, and soil nonlinearity had significant effect on the displacement of retaining walls. Also, the rocking displacement was observed to be an important component of the total displacement. The incline angle at the back of a wall prevented the wall from completely overturning without altering the total displacements. The unit weight of wall material and the friction angle of the backfill had negligible effect on the computed displacements due to induced hydrodynamic forces. Examples of displacement-based design were performed. A comparison of computed displacements agreed well with the observed ones for a wall test in a centrifuge. The results revealed that the leaning type of retaining wall reduced the base width for the displacement-based design.
Book Synopsis Seismic Performance and Modeling of Reinforced Concrete and Post-Tensioned Precast Concrete Shear Walls by : Ahmet Can Tanyeri
Download or read book Seismic Performance and Modeling of Reinforced Concrete and Post-Tensioned Precast Concrete Shear Walls written by Ahmet Can Tanyeri and published by . This book was released on 2014 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: Past earthquakes have shown examples of unsatisfactory performance of buildings using reinforced concrete structural walls as the primary lateral-force-resisting system. In the 1994 Northridge earthquake, examples can be found where walls possessed too much overstrength, leading to unintended failure of collectors and floor systems, including precast and post-tensioned construction. In the 2010 Maule Chile earthquake, many structural wall buildings sustained severe damage. Although Chilean design standards result in different reinforcement detailing than is common in U.S. walls, the failure patterns raise concerns about how well conventionally reinforced structural walls in U.S. buildings will perform during the next earthquake. Alternative wall design philosophies that offer more predictable response, with better damage control, should be investigated. After the Mw 8.8 Chile earthquake, the 15-story Alto Rio building in Concepción sustained failures near the base, overturned, and came to rest on its side. The collapse of the Alto Rio building was significant because it was designed using the Chilean Building Code NCh433. Of96, which requires the use of ACI 318-95 for design of reinforced concrete structural elements intended to resist design seismic forces. The failure of the Alto Rio building is significant for many reasons. It is the first modern shear wall building of its type to collapse by overturning during an earthquake. The building is studied using forensic data and structural models of the framing system subjected to earthquake shaking. The study identifies the likely failure mechanism and suggests areas for which design and detailing practices could be improved. The capabilities and shortcomings of the analyses to identify details of the failure mechanism are themselves important outcomes of the study. A second study explores the behavior of structural wall buildings using unbonded post-tensioned structural walls. Such walls offer the opportunity to better control yielding mechanisms and promote self-centering behavior. The study focuses on the measured responses of a full-scale, four-story building model tested on the E-Defense shaking table in Japan. The seismic force-resisting system of the test building comprised two post-tensioned (PT) precast frames in one direction and two unbonded PT precast walls in the other direction. The building was designed using the latest code requirements and design recommendations available both in Japan and the U.S., including the ACI ITG-5.2-09. The test building was subjected to several earthquake ground motions, ranging from serviceability level to near collapse. Analytical studies were carried out to test the capability of the structural models to replicate behaviors important to structural engineers, and to assess whether available analysis tools are sufficient to model dynamic behavior that results when a full-scale building is subjected to realistic earthquake ground shaking. Measured response data from such an outstanding test provides an opportunity to fully understand the response characteristics of PT walls and assess the ability of nonlinear analytical models to reproduce important global and local responses, including three-dimensional system interactions, both prior to and after loss of significant lateral strength. Moreover, this study to assess behavior and system interaction of PT walls leads to improvements of the current design ideas and performance expectations. The present study examines both the collapse of the Alto Rio building in Chile and the shaking table tests of the unbonded post-tensioned wall building in Japan. The collapse study suggests areas of improvement in current design and detailing practice. The shaking table study suggests an alternative approach to design of shear walls in buildings. Both studies demonstrate the use of modern structural analysis tools to interpret building responses to earthquake shaking. Taken together, the studies provide added confidence in earthquake simulation capabilities and demonstrate alternatives for designing earthquake-resistant buildings that use structural walls.
Book Synopsis Experimental and Numerical Modeling of Seismic Earth Pressures on Retaining Walls with Cohesive Backfills by : GABRIEL ALFONSO. CANDIA
Download or read book Experimental and Numerical Modeling of Seismic Earth Pressures on Retaining Walls with Cohesive Backfills written by GABRIEL ALFONSO. CANDIA and published by . This book was released on 2013 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: Observations from recent earthquakes show that all types of retaining structures with non-liquefiable backfills perform very well and there is limited evidence of damage or failures related to seismic earth pressures. Even retaining structures designed only for static loading have performed well during strong ground motions suggesting that special seismic design provisions may not be required in some cases. The objective of this study was to characterize the seismic interaction of backfill-wall systems using experimental and numerical models, with emphasis on cohesive soils, and to review the basic assumptions of current design methods. In the experimental phase of this research, two sets of centrifuge models were conducted at the Center for Geotechnical modeling in UC Davis. The first experiment consisted of a basement wall and a freestanding cantilever wall with level backfill, while the second one consists of a cantilever wall with sloping backfill. The soil used in the experiments was a compacted low plasticity clay. Numerical simulations were performed using FLAC2-D code, featuring non-linear constitutive relationships for the soil and interface elements. The non-linear hysteretic constitutive UBCHYST was used to model the level ground experiment and Mohr-Coulomb with hysteretic damping was used to model the sloping backfill experiment. The simulations captured the most important aspects of the seismic responses, including the ground motion propagation and the dynamic soil-structure interaction. Special attention was given to the treatment of boundary conditions and the selection of the model parameters. The results from the experimental and numerical analysis provide information to guide the designers in selecting seismic design loads on retaining structures with cohesive backfills. The experimental results show that the static and seismic earth pressures increase linearly with depth and that the resultant acts at 0.35H-0.4H, as opposed to 0.5-0.6H assumed in current engineering practice. In addition, the observed seismic loads are a function of the ground motion intensity, the wall type and backfill geometry. In general, the total seismic load can be expressed using Seed and Whitman's (1970) notation as: Pae=Pa+dPae, where Pa is the static load and dPae is the dynamic load increment. While the static load is a function of the backfill strength, previous stress history and compaction method, the dynamic load increment is a function of the free field PGA, the wall displacements, and is relatively independent of cohesion. In level ground, the dynamic load coefficient can be expressed as dKae=1/2gH2(0.68PGAff/g) for basement walls and dKae=1/2gH2(0.42PGAff/g) for cantilever walls; these results are consistent with similar experiments performed in cohesionless soils (Mikola & Sitar, 2013. In the sloping ground experiment the seismic coefficient came out to dKae=1/2gH2(0.7PGAff/g), which is consistent with Okabe's (1926) Coulomb wedge analysis of the problem. However, that slope was stable under gravity loads even without the presence of the retaining wall (FS=1.4). Measured slope displacements were very small and in reasonable good agreement with the predictions made with the Bray and Travasarou (2007) semi-empirical method. The experimental data was not sufficient to determine accurately the point of action of the seismic loads. However, the numerical simulations and Okabe's (1926) limit state theory suggest that the resultant acts between 0.37H-0.40H for typical values of cohesion. While the resultant acts at a point higher than 0.33H with increasing cohesion, the total seismic moment is reduced due to the significant reduction in the total load Pae, particularly for large ground accelerations. The results also show that typical retaining walls designed with a static factor of safety of 1.5 have enough strength capacity to resist ground accelerations up to 0.4g. This observation is consistent with the field performance of retaining walls as documented by Clough and Fragaszy (1977) and the experimental results by al Atik and Sitar (2010) and Geraili and Sitar (2013). The evaluation of earth pressures at the wall-backfill interface continues to be a technical challenge. Identified sources of error in the present study include the behavior of pressure sensors, the geometric and mass asymmetry of the model and the dynamic interaction between the model and the container. While these centrifuge experiments reproduced the basic response of prototype models, ultimately, instrumented full-scale structures are most essential to fully characterize the response of tall walls and deep basements with varieties of backfill.
Book Synopsis Seismic Earth Pressures on Retaining Structures and Basement Walls in Cohesionless Soils by : Roozbeh Geraili Mikola
Download or read book Seismic Earth Pressures on Retaining Structures and Basement Walls in Cohesionless Soils written by Roozbeh Geraili Mikola and published by . This book was released on 2012 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Observations of the performance of basement walls and retaining structures in recent earthquakes show that failures of basement or deep excavation walls in earthquakes are rare even if the structures were not designed for the actual magnitude of the earthquake loading. Failures of retaining structures are most commonly confined to waterfront structures retaining saturated backfill with liquefaction being the critical factor in the failures. Failures of other types of retaining structures are relatively rare and usually involve a more complex set of conditions, such as sloping ground either above or below the retaining structure, or both. While some failures have been observed, there is no evidence of a systemic problem with traditional static retaining wall design even under quite severe loading conditions. No significant damage or failures of retaining structures occurred in the recent earthquakes such as Wenchuan earthquake in China (200) and, or subduction zone generated earthquakes in Chile (2010) and Japan (2011). Therefore, this experimental and analytical study was undertaken to develop a better understanding of the distribution and magnitude of seismic earth pressures on cantilever retaining structures. The experimental component of the study consists of two sets of dynamic centrifuge model experiments. In the first experiment two model structures representing basement type setting were used, while in the second test a U-shaped channel with cantilever sides and a simple cantilever wall were studied. All of these structures were chosen to be representative of typical designs. Dry medium-dense sand with relative density on the order of from 75% to 80% was used as backfill. Results obtained from the centrifuge experiments were subsequently used to develop and calibrate a two-dimensional, nonlinear, finite difference model built on the FLAC platform. The centrifuge data consistently shows that for the height of structures considered herein, i.e. in the range of 20-30 ft, the maximum dynamic earth pressure increases with depth and can be reasonably approximated by a triangular distribution This suggests that the point of application of the resultant force of the dynamic earth pressure increment is approximately 1/3H above the base of the wall as opposed to 0.5-0.6 H recommended by most current design procedures. In general, the magnitude of the observed seismic earth pressures depends on the magnitude and intensity of shaking, the density of the backfill soil, and the type of the retaining structures. The computed values of seismic earth pressure coefficient (delta Kae) back calculated from the centrifuge data at the time of maximum dynamic wall moment suggest that for free standing cantilever retaining structures seismic earth pressures can be neglected at accelerations below 0.4 g. While similar conclusions and recommendations were made by Seed and Whitman (1970), their approach assumed that a wall designed to a reasonable static factor of safety should be able to resist seismic loads up 0.3 g. In the present study, experimental data suggest that seismic loads up to 0.4 g could be resisted by cantilever walls designed to an adequate factor of safety. This observation is consistent with the observations and analyses performed by Clough and Fragaszy (1977) and Fragaszy and Clough (1980) and Al-Atik and Sitar (2010) who concluded that conventionally designed cantilever walls with granular backfill could be reasonably expected to resist seismic loads at accelerations up to 0.4 g. Finally, numerical models using FLAC finite difference code were quite successful and able to produce a reasonably good agreement with the results of the centrifuge experiments. However, while the finite difference models were able to capture the main aspects of the seismic response observed in the centrifuge experiments, the results of the analyses were highly sensitive to the selection of soil and interface parameters. Therefore, numerical models used for future designs should be carefully calibrated against experimental data in order to provide reliable results.
Book Synopsis Design and Performance of Earth Retaining Structures by : Philip C. Lambe
Download or read book Design and Performance of Earth Retaining Structures written by Philip C. Lambe and published by . This book was released on 1990 with total page 926 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the 1990 Specialty Conference on Design and Performance of Earth-Retaining Structures, held in Ithaca, New York, June 18-21, 1990. Sponsored by the Geotechnical Engineering Division of ASCE. This Geotechnical Special Publication contains 50 papers on the design and performance of earth-retaining structures. Topics include historical perspectives, wall selection, contracting practices, waterfront structures, gravity walls, mechanically stabilized systems, cast-in-place walls, soil nailing, tied-back excavations, and seismic design. Papers survey the current state of the practice for earth retention and support, detail the rapid and profound changes to design and construction practices in the past 20 years, and forecast technological developments that are likely to carry the practice into the next century. Sixteen invited papers by international experts address aspects of each of the general topics, including trends in ground movements, effects of material selection and construction practices, and advances in design analyses and procedures. Other papers address specific case histories of various types of earth-retaining structures, provide results of performance monitoring, compare predicted to actual performance, and assess the impacts of construction practice and design procedures on performance.
Book Synopsis Retaining-walls for Earth by : Malverd Abijah Howe
Download or read book Retaining-walls for Earth written by Malverd Abijah Howe and published by . This book was released on 1886 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Retaining-walls for Earth by : Malverd Abijah Howe
Download or read book Retaining-walls for Earth written by Malverd Abijah Howe and published by . This book was released on 1896 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Rotational Response of Toe-restrained Retaining Walls to Earthquake Ground Motions by : Robert M. Ebeling
Download or read book Rotational Response of Toe-restrained Retaining Walls to Earthquake Ground Motions written by Robert M. Ebeling and published by . This book was released on 2006 with total page 325 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis NEHRP Commentary on the Gidelines for the Seismic Rehabilitation of Buildings by : Eugene Zeller
Download or read book NEHRP Commentary on the Gidelines for the Seismic Rehabilitation of Buildings written by Eugene Zeller and published by DIANE Publishing. This book was released on 2000-06 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document from the National Earthquake Hazards Reduction Program (NEHRP) was prepared for the Building Seismic Safety Council (BSSC) with funding from the Federal Emergency Management Agency (FEMA). It provides commentary on the NEHRP Guidelines for the Seismic Rehabilitation of Buildings. It contains systematic guidance enabling design professionals to formulate effective & reliable rehabilitation approaches that will limit the expected earthquake damage to a specified range for a specified level of ground shaking. This kind of guidance applicable to all types of existing buildings & in all parts of the country has never existed before. Illustrated.
