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Numerical Analysis On Seismic Response Of Cantilever Retaining Wall Systems And Fragility Analysis On Motion Response
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Book Synopsis Numerical Analysis on Seismic Response of Cantilever Retaining Wall Systems and Fragility Analysis on Motion Response by : Siavash Zamiran
Download or read book Numerical Analysis on Seismic Response of Cantilever Retaining Wall Systems and Fragility Analysis on Motion Response written by Siavash Zamiran and published by . This book was released on 2017 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this investigation, seismic response of retaining walls constructed with cohesive and cohesionless backfill materials was studied. Fully dynamic analysis based on finite difference method was used to evaluate the performance of retaining walls during the earthquake. The analysis response was verified by the experimental study conducted on a retaining wall system with cohesive backfill material in the literature. The effects of cohesion and free-field peak ground acceleration (PGA) on seismic earth thrust, the point of action of earth thrust, and maximum wall moment during the earthquake were compared with analytical and experimental solutions. The numerical results were compared with various analytical solutions. The motion characteristics of the retaining wall during the earthquake were also considered. The relative displacement of the walls with various backfill cohesions, under different ground motions, and free-field PGAs were investigated. Current analytical and empirical correlations developed based on Newmark sliding block method for estimating retaining wall movement during earthquakes were compared with the numerical approach. Consequently, fragility analyses were conducted to determine the probability of damage to the retaining walls. To evaluate the fragility of the studied models, specific failure criterion was chosen for retaining walls based on the suggested methods in practice. Using numerical approaches, the effects of soil-wall interaction and wall rigidity on the seismic response of retaining walls were also evaluated in earthquake conditions for both cohesive and cohesionless backfill materials. According to the findings, practical correlations were presented for conducting the seismic design of retaining 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 Numerical Analysis of Seismic Responses of Geosynthetic Reinforced Soil (GRS) Retaining Walls Subjected to Horizontal and Vertical Seismic Loadings by :
Download or read book Numerical Analysis of Seismic Responses of Geosynthetic Reinforced Soil (GRS) Retaining Walls Subjected to Horizontal and Vertical Seismic Loadings written by and published by . This book was released on 2021 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Structural Response Computations in Earthquake Engineering by : A. H. Barbat
Download or read book Structural Response Computations in Earthquake Engineering written by A. H. Barbat and published by . This book was released on 1989 with total page 622 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Seismic Response Of Geosynthetic Reinforced Soil Wall Models Using Shaking Table Tests by :
Download or read book Seismic Response Of Geosynthetic Reinforced Soil Wall Models Using Shaking Table Tests written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Use of soil retaining walls for roads, embankments and bridges is increasing with time and reinforced soil retaining walls are found to be very efficient even under critical conditions compared to unreinforced walls. They offer competitive solutions to earth retaining problems associated with less space and more loads posed by tremendous growth in infrastructure, in addition to the advantages in ease and cost of construction compared to conventional retaining wall systems. The study of seismic performance of reinforced soil retaining walls is receiving much attention in the light of lessons learned from past failures of conventional retaining walls. Laboratory model studies on these walls under controlled seismic loading conditions help to understand better how these walls actually behave during earthquakes. The objective of the present study is to investigate the seismic response of geosynthetic reinforced soil wall models through shaking table tests. To achieve this, wrap faced and rigid faced reinforced soil retaining walls of size 750 × 500 mm in plan and 600 mm height are built in rigid and flexible containers and tested under controlled dynamic conditions using a uni-axial shaking table. The effects of frequency and acceleration of the base motion, surcharge pressure on the crest, number of reinforcing layers, container boundary, wall structure and reinforcement layout on the seismic performance of the retaining walls are studied through systematic series of shaking table tests. Results are analyzed to understand the effect of each of the considered parameters on the face displacements, acceleration amplifications and soil pressures on facing at different elevations of the walls. A numerical model is developed to simulate the shaking table tests on wrap faced reinforced soil walls using a computer program FLAC (Fast Lagrangian Analysis of Continua). The experimental data are used to validate the numerical model and parametric studies are carried out on 6 m hei.
Book Synopsis Seismic Analysis of Cantilever Retaining Wall, Including Soil-Structure Interaction by : T.D. Doshi
Download or read book Seismic Analysis of Cantilever Retaining Wall, Including Soil-Structure Interaction written by T.D. Doshi and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cantilever retaining walls are required to retain earth at a change in ground elevation. Cantilever retaining walls are made of reinforced concrete and consist of a thin stem and a base slab. During a seismic event, it is evident that earthquake response of each component of this complex system (i.e., wall, soil and structure) may affect substantially the response of the rest and vice versa. This earthquake response which is described as soil-structure interaction is generally ignored in the design process of cantilever retaining walls, though it has been shown that ignoring such effect may lead to unsafe seismic design. Flexibility of soil medium below foundation decreases the overall stiffness of the cantilever retaining wall structure, resulting in a subsequent increase in the displacement and reaction of the retaining wall structure. Hence in the present study, an attempt is made to observe the effects of soil-structure interaction on the change displacement and reaction of cantilever retaining wall considering different types of retaining wall system and variations of factors such as different earthquake zones (viz., 2, 3, 4, 5) and different support conditions (viz., fixed, fixed but, and foundation). The analysis of a retaining wall model has been modeled and analyzed using STAAD PRO software. The study shows that displacement and reaction increases with increase in the earthquake zones for different types of retaining walls with different support conditions. Therefore, the present study helps in understanding the effect of soil-structure interaction on cantilever retaining walls, which might help to improve the seismic behavior of cantilever retaining wall and also lead to a more economic design.
Book Synopsis Seismic Fragility Assessment and Resilience of Reinforced Masonry Shear Wall Systems by : Shadman Hosseinzadeh
Download or read book Seismic Fragility Assessment and Resilience of Reinforced Masonry Shear Wall Systems written by Shadman Hosseinzadeh and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reinforced Masonry Shear Walls (RMSWs) are commonly used in low- to high-rise buildings as the lateral load resisting system. There have been several experimental and analytical studies that evaluated the seismic response of RMSW either as a single element (i.e., planar rectangular walls) or as a building consisting of planar walls. However, research on Reinforced Masonry Shear Walls (RMSWs) with end-confined Boundary Elements and flanged shear walls are scarce, especially considering the effects of design parameters on the system's seismic inelastic response. The end confined RMSWs proved to have a higher level of ductility since they can postpone the reinforcement buckling in compression while increasing the compressive strength of the shear walls' component at the same time. The objectives of the current study are to: (i) assess the seismic performance and collapse capacity of the RMSW with end confined Boundary Elements and Flanged shear walls at both structural element, and entire building level, (ii) evaluate the seismic resilience and functionality of the RMSW system when subjected to severe earthquake events, (iii) to quantify and assess the resilience index versus the uncertainty of the studied parameters. To achieve the first goal, at the structural element level, the RM shear walls were designed with different heights to investigate the effect of the wall's height on its seismic performance. The impact of utilizing flanged walls was assessed and characterized through new seismic performance standards and assessment approaches. In this respect, a modified macro-modelling approach has been proposed to numerically model and capture the inelastic behaviour of the RM shear walls. The proposed model can capture both flexural and shear deformations. The nonlinear model was first validated against experimental data of RM rectangular and flanged shear walls and walls with masonry boundary elements (MBEs); afterwards, the model has been utilized in simulating RM flanged wall archetypes. Collapse risk evaluation has been conducted by subjecting the wall's numerical model to various ground motions scaled at different intensity levels. Nonlinear static pushover analysis and incremental dynamic analysis (IDA) has been conducted on numerical models. Quantification of the seismic parameters of the flanged wall system, including period-based ductility, overstrength, and collapse margin ratios, has been conducted to help better understanding the seismic response and collapse capacity of the component. Lastly, the seismic resilience of the archetypes against the expected collapse risk was evaluated, before and after adding flanges and boundary elements to the walls, in terms of functionality curves. Damage levels were considered as performance level functions correlated to the earthquake intensity and were used to estimate total loss and recovery time of the archetypes. To reach the second objective, the study is extended to investigate the impact of using end-confined masonry boundary elements at the building level by the adoption of such elements for multi-storey RMSW buildings. In this respect, the developed macro-model was updated to take the impact of out-of-plane walls' shear flexibility into account, after adding an out-of-plane shear spring. The outcome of the test results of a one-third scale two-storey building was used to validate the modelling approach at the system level. Subsequently, the archetype buildings were subjected to multiple ground motion records using Incremental Dynamic Analysis to identify the collapse initiation and derive fragility curves. The results indicate a significant enhancement of the resilience index by using end-confined Masonry Boundary Elements (MBEs). To accomplish the third objective, a probabilistic approach was utilized to quantify the seismic resilience index of the RMSW building with MBEs located in a high seismic zone of Canada. The uncertainties associated with the losses and expected recovery time and sensitivity of each parameter were studied and depicted using the resilience index threshold and the Monte Carlo simulation method. The storey shear contribution of in-plane and out-of-plane walls were also quantified for all archetype buildings. The results indicate sufficient seismic resilience of ductile RMSW buildings with MBEs when subjected to the Maximum Credible Earthquake (MCE). The findings of this part are crucial for earthquake mitigation practice and disaster risk reduction plans.
Book Synopsis Response Spectrum Method in Seismic Analysis and Design of Structures by : Ajaya Kumar Gupta
Download or read book Response Spectrum Method in Seismic Analysis and Design of Structures written by Ajaya Kumar Gupta and published by Routledge. This book was released on 2017-11-22 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: New developments in the response spectrum method have led to calculations in seismic stresses that are more accurate, and usually lower, than those obtained by conventional methods. This new textbook examines the wealth of information on the response spectrum method generated by the latest research and presents the background theory in simplified form. Applications of these methods is essential in the seismic design of critical structures, such as nuclear power plants and petroleum facilities. In new construction, the reduced seismic stresses will result in efficient and economic design. For facilities already built, these more accurate methods can be used where the facility is being reassessed for higher loads and in the calculation of margins. Written by an acknowledged expert in this and related fields, this volume is ideal as a graduate text for courses in structural and earthquake engineering. It is also an excellent reference for civil, structural, mechanical, and earthquake engineers.
Book Synopsis Structural Dynamics of Earthquake Engineering by : S Rajasekaran
Download or read book Structural Dynamics of Earthquake Engineering written by S Rajasekaran and published by Elsevier. This book was released on 2009-05-30 with total page 909 pages. Available in PDF, EPUB and Kindle. Book excerpt: Given the risk of earthquakes in many countries, knowing how structural dynamics can be applied to earthquake engineering of structures, both in theory and practice, is a vital aspect of improving the safety of buildings and structures. It can also reduce the number of deaths and injuries and the amount of property damage. The book begins by discussing free vibration of single-degree-of-freedom (SDOF) systems, both damped and undamped, and forced vibration (harmonic force) of SDOF systems. Response to periodic dynamic loadings and impulse loads are also discussed, as are two degrees of freedom linear system response methods and free vibration of multiple degrees of freedom. Further chapters cover time history response by natural mode superposition, numerical solution methods for natural frequencies and mode shapes and differential quadrature, transformation and Finite Element methods for vibration problems. Other topics such as earthquake ground motion, response spectra and earthquake analysis of linear systems are discussed. Structural dynamics of earthquake engineering: theory and application using Mathematica and Matlab provides civil and structural engineers and students with an understanding of the dynamic response of structures to earthquakes and the common analysis techniques employed to evaluate these responses. Worked examples in Mathematica and Matlab are given. Explains the dynamic response of structures to earthquakes including periodic dynamic loadings and impulse loads Examines common analysis techniques such as natural mode superposition, the finite element method and numerical solutions Investigates this important topic in terms of both theory and practise with the inclusion of practical exercise and diagrams
Book Synopsis Soil-structure interaction in seismic analysis by : Alexander Tyapin
Download or read book Soil-structure interaction in seismic analysis written by Alexander Tyapin and published by ASV Construction. This book was released on 2019-06-11 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soil-structure interaction (SSI) is an important phenomenon in the seismic response analysis. As seismologists describe seismic excitation in terms of the seismic motion of certain control point at the free surface of the initial site, the question is whether the same point of the structure (after structure appears) will have the same seismic response motion in case of the same seismic event. If yes, then seismic motion from seismologists is directly applied to the base of the structure (it is called “fixed-base analysis”), and they say that “no SSI occurs”’ (though literally speaking soil is forcing structure to move, so interaction is always present). This is a conventional approach in the field of civil engineering. However, if heavy and rigid structure (sometimes embedded) is erected on medium or soft soil site, this structure changes the seismic response motion of the soil as compared to the initial free-field picture. Such a situation is typical for Nuclear Power Plants (NPPs), deeply embedded structures, etc. The book describes different approaches to SSI analysis and different SSI effects. Special attention is paid to the Combined Asymptotic Method (CAM) developed by the author and used for the design of NPPs in seismic regions. Nowadays, some civil structures have parameters comparable to those of NPPs (e.g., masses and embedment), so these approaches become useful for the civil structural engineers as well.
Book Synopsis Seismic Response Verification of Reinforced Concrete Structural Wall Systems by : Rodolfo Alvarez Sanchez
Download or read book Seismic Response Verification of Reinforced Concrete Structural Wall Systems written by Rodolfo Alvarez Sanchez and published by . This book was released on 2020 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reinforced concrete structural walls are frequently used as a lateral load resisting system in buildings. In some buildings affected by relatively recent seismic events, the response of the structural walls, traditionally labeled as excellent, has been somewhat unexpected and deserves attention.This dissertation focuses on enhanced numerical methodologies for the verification of the seismic response, including softening, of reinforced concrete structural wall systems. First, a Truss Model for reinforced concrete coupled structural walls is developed. Bar bond-slip, dowel action, and confining effect of the foundation are considered. Two cyclic tests, on scaled seven-story coupled walls (from literature), are used for validation. It is shown that the compressed wall piers resist most of the base shear force and that the coupling beams at lower levels develop the largest shear forces. Second, using the same benchmark test specimens, two models for the nonlinear cyclic analysis of reinforced concrete coupled walls are developed, i.e., Modified Beam-Truss Model and Enhanced Beam-Truss Model. The role of the strain penetration in diagonally reinforced coupling beams on the hysteretic energy dissipated is studied. It is verified that the computational-efficient proposed models predict well the overall response and the sliding shear failures of coupling beams. Third, the Beam-Truss Model developed in a previous study for the nonlinear cyclic analysis of reinforced concrete components is extended to compute out-of-plane buckling in structural walls. The novel Beam-Truss Model computes accurately the force-displacement responses and the buckling behavior of three test specimens reported in literature used for validation. Finally, the Beam-Truss Model is enhanced to compute the out-of-plane nonlinear shear response of wall piers in the analysis of Core-Wall-Building systems. Using the proposed model and pushover analyses, a comprehensive study on a 14-story archetype Core-Wall building is carried out. It is shown that the in-plane shear response has a large influence on the lateral strength and displacement capacity, whereas the out-of-plane shear response mainly influences the displacement capacity.
Book Synopsis Time Domain Simulation of Soil-retaining Wall Interaction in Elastic and Elastoplastic Soils by : Charikleia Prassa
Download or read book Time Domain Simulation of Soil-retaining Wall Interaction in Elastic and Elastoplastic Soils written by Charikleia Prassa and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Retaining wall systems are widely used throughout seismically active areas like California. They represent key elements of important constructed facilities and their potential damage is connected with significant physical and economic consequences. While their design for static applications has been practiced by many sectors, their seismic design has not been extensively developed with a lack of accurate guidelines in the excisting design codes. The current study aims at the investigation of the dynamic response of freeway retaining walls that are used in highways of California and have been designed based on the existing Caltrans specifications and tools. The seismic response of those walls is a very complex phenomenon as it depends on the soil-retaining wall-earthquake interaction. The response becomes even more complex with the addition of a sound wall at the top of the retaining wall. The development of rigorous numerical models in order to capture the dynamic response of the wall as well as the factors that contribute to the failure of the sound wall is the main objective of this work. First, one set of numerical models was developed in order to validate a full scale test on two retaining walls designed according to Caltrans specifications and secondly, another set of models was developed in order to analyze parametrically the effect of the triad soil-retaining wall-earthquake to the system and contribution of sound wall. Main observation from the results of the analysis is that the dynamic response of such a retaining system is the combined result of many factors such as the predominant frequency of the excitation and the eigenfrequency of the structure.
Book Synopsis A study on seismic response of reinforced structures retrofitted with fluid viscous dampers in shear walls by : Sachin Kuckian
Download or read book A study on seismic response of reinforced structures retrofitted with fluid viscous dampers in shear walls written by Sachin Kuckian and published by GRIN Verlag. This book was released on 2019-08-05 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: Master's Thesis from the year 2015 in the subject Engineering - Geotechnology, grade: 9.44, , course: Masters (Structural Engineering), language: English, abstract: The present study investigates the seismic behavior of multi-story building using damping devices strategically located within the lateral load resisting elements. It concentrates on a retrofitting strategy with passive energy dissipation device known as Fluid Viscous Damper (FVD) which will be applicable to new design as well as retrofitting existing buildings to ensure seismic safety by fitting damping devices which can transform a wall panel into a damping element. The first study involves analysis of a nine-story model having cut-outs and the use of the dampers of different configuration in these structures. The second study involves the use the diagonal brace configuration dampers provided in the cutout sections of 2D 9, 18, 27 storey structures and 3D 27 storey with core wall structure at three consecutive story levels each. For the second study, the cut out locations is varied depending on their relative positions. The relative position is the ratio of the total height of the structure to the upper edge of the topmost cut-out. These structures were initially modeled and time history analysis was performed on the structure without FVD and the structure retrofitted with FVD. Three different ground motions were used for the analysis. Results of the un- retrofitted structures are then compared with a retrofitted structure in terms of peak story displacements, roof accelerations, and pseudo-spectral accelerations. Study shows that there has been a significant reduction in seismic demands for a structure retrofitted with FVD in terms of peak storey displacements, pseudo-spectral accelerations and roof accelerations when the dampers are placed at lower three cut outs i.e. with high relative position. It is also observed that damping coefficient value obtained is least for upper toggle-brace configuration out of the four different damper configurations and with maximum reduction compared to other configurations. For modeling and analysis purpose the software SAP2000® is used. Through the study it could be concluded that FVD significantly reduces the seismic demands of the structure in terms of peak storey displacements, pseudo-spectral accelerations and roof accelerations. This suggests that FVDs can be efficiently used in retrofitting. Also damping coefficient value obtained is least for upper toggle-brace configuration out of the four different damper configurations suggesting this is the most efficient configuration for retrofitting.
Book Synopsis Seismic Response Assessment of Thin Boundary Elements of Special Concrete Shear Walls by : Carlos Alberto Arteta
Download or read book Seismic Response Assessment of Thin Boundary Elements of Special Concrete Shear Walls written by Carlos Alberto Arteta and published by . This book was released on 2015 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Damage observed near the base of shear walls of reinforced concrete buildings after the Chile (2010) and New Zealand (2011) earthquakes are signs of shortcomings in the design of walls that need to be addressed. This investigation presents results of an experimental test program on ten reinforced concrete rectangular prisms representative of the flexural compression zone of flanged shear walls. The tested elements have transverse reinforcement detailing that matches or exceeds modern code requirements for special boundary elements. The main test variables were the amount and spacing (both vertical and horizontal) of the hoop and crosstie reinforcement. The elements were subjected to monotonically increasing axial compression until failure. Effects of strain gradient (both through the wall length and along the wall height) and effects of wall shear are not represented in the present tests. Nonetheless, the axial compression tests provide insights into the behavioral characteristics of actual wall boundaries. The global force shortening behavior of the specimens was commanded by a thin core which integrity was heavily compromised due to cover spalling, rebar buckling and out-of-plane instability. Measured load-displacement relations did not exhibit an acceptable ductile behavior suggesting that current building code requirements for special boundary elements do not necessarily achieve effective confinement to be protected against brittle axial failure. Enhanced detailing (increasing the volumetric ratio of confinement reinforcement and decreasing its horizontal spacing) improved behavior but did not produce ductile response in all cases. Reported damage extension concentrated over length corresponding to two-and-half times the thickness of the specimens. Compressive strain limits for stable behavior are proposed to be function of the gage length over which they are measured. Bar buckling reduced the load carrying capacity of the reinforced concrete prisms because of the strength loss suffered by the longitudinal reinforcement, but also because it prevented the effective confinement of the concrete core. An experimental campaign comprising 48 analytical specimens allowed studying the relationship between tie spacing and stiffness, and the diameter of the longitudinal bars, that influenced their response when undergoing lateral instability (inelastic buckling). The behavior of tied bars undergoing lateral instability in the inelastic range is highly influenced by the relative restrictive tie spacing over which bar buckling is forced into, and the relative stiffness of the transverse ties and the longitudinal bar. The experiments assume a rigid contact between the bar and the tie, therefore hook opening is not modeled. For the range of tie stiffness and bar geometries tested, the results indicate that the tie spacing has to be smaller than 4.5 times the bar diameter to prevent bar buckling over a large range of plastic axial strains. Empirical core stress strain curves, accounting for bar buckling, are reported for point wise strain measurements, as well as for average axial strains recorded within the damaged region. The results show that usable strain limits, to guarantee a stable core response in pure compression, are between 1.1 and 2.0%. Average empirical core stress strain curves are proposed for modeling purposes. Implication of the compressive strain limits observed are evaluated in a hazard-consistent manner by means of the Conditional Scenario Spectra (CSS). The CSS is a set of realistic earthquake spectra with assigned rates of occurrence that reproduce the hazard at a site. Structural responses are obtained by means of numerical analysis of a multistory shear wall under the seismic demand of more than eight-hundred ground motions consistent with the CSS. The case study allows estimating risk curves to evaluate the likelihood of exceeding certain threshold compressive strains in the boundary of the cross section. The single case numerical model showed that the limited strain capacity of these elements is only likely to negatively impact the behavior of the wall system at risk levels beyond the code-based expectations of good behavior.
Book Synopsis Seismic Behaviour and Design of Irregular and Complex Civil Structures III by : Dietlinde Köber
Download or read book Seismic Behaviour and Design of Irregular and Complex Civil Structures III written by Dietlinde Köber and published by Springer Nature. This book was released on 2020-03-06 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents state-of-the-art knowledge on problems of the effects of structural irregularities on their seismic response. It also covers specific spatial and rotational seismic loads on these structures. Rapid progress in respective research on irregular structures and unconventional seismic loads requires prompt updates of the state of the art in this area. These problems are of particular interest to both researchers and practitioners because these are non-conservative effects compared with the approach of the traditional seismic design (e.g. Eurocode 8, Uniform Building Code etc.). This book will be of particular interest to researchers, PhD students and engineers dealing with design of structures under seismic excitations.
Book Synopsis Rocking of Foundations by : Zhuo Jun "George." Hu
Download or read book Rocking of Foundations written by Zhuo Jun "George." Hu and published by . This book was released on 2006 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Transactions of the American Society of Civil Engineers by : American Society of Civil Engineers
Download or read book Transactions of the American Society of Civil Engineers written by American Society of Civil Engineers and published by . This book was released on 2006 with total page 1264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vols. 29-30 contain papers of the International Engineering Congress, Chicago, 1893; v. 54, pts. A-F, papers of the International Engineering Congress, St. Louis, 1904.
