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Showing papers on "Earthquake resistant structures published in 2014"


Journal ArticleDOI
TL;DR: The self-centering rocking steel-braced frame is a high-performance system that can prevent major structural damage and minimize residual drifts during large earthquakes as mentioned in this paper, which consists of braced steel frames that are designed to remain elastic and allowed to rock off their foundation.
Abstract: The self-centering rocking steel-braced frame is a high-performance system that can prevent major structural damage and minimize residual drifts during large earthquakes. It consists of braced steel frames that are designed to remain elastic and allowed to rock off their foundation. Overturning resistance is provided by elastic post-tensioning, which provides a reliable self-centering restoring force, and replaceable structural fuses that dissipate energy. The design concepts of this system are examined and contrasted with other conventional and self-centering seismic force resisting systems. Equations to predict the load-deformation behavior of the rocking system are developed. Key limit states are investigated including desired sequence of limit states and methods to help ensure reliable performance. Generalized design methods for controlling the limit states are developed. The design concepts are then applied to a six-story prototype structure to illustrate application of the rocking steel fram...

139 citations


Journal ArticleDOI
TL;DR: In this article, the authors numerically investigated the three-dimensional seismic response of six reinforced concrete bridges located in Oakland, California, 3 km from the Hayward fault, using two components of horizontal excitation, three dimensional nonlinear response history analyses were performed for two seismic hazard levels with return periods of 975 and 2,475 years, respectively.
Abstract: This paper numerically investigates the three-dimensional seismic response of six reinforced concrete bridges hypothetically located in Oakland, California, 3 km from the Hayward fault. Three of the bridges are 17 m tall and three are 8 m tall. Three types of column-foundation designs are studied: (1) columns that form flexural plastic hinges, which are conventionally designed according to CALTRANS seismic design criteria; (2) columns on rocking pile foundations that are designed to remain elastic; and (3) columns designed to remain elastic that are supported on rocking shallow foundations. The bridges with rocking foundations use lead rubber bearings at the abutments to enhance strength, stiffness, and hysteretic energy dissipation. Using two components of horizontal excitation, three-dimensional nonlinear response history analyses are performed for two seismic hazard levels with return periods of 975 and 2,475 years, respectively. At both levels of shaking, the conventionally designed bridges experience substantial inelastic deformations and damage in the columns, whereas the bridges with rocking foundations result in negligible structural damage and a nominally elastic response and small residual deformations.

62 citations


Journal ArticleDOI
TL;DR: In this paper, a series of large-scale hybrid simulation tests were performed to investigate the seismic performance of the self-centering rocking steel frame and in particular, the ability of the controlled rocking system to self-center the entire building.
Abstract: SUMMARY The self-centering rocking steel frame is a seismic force resisting system in which a gap is allowed to form between a concentrically braced steel frame and the foundation. Downward vertical force applied to the rocking frame by post-tensioning acts to close the uplifting gap and thus produces a restoring force. A key feature of the system is replaceable energy-dissipating devices that act as structural fuses by producing high initial system stiffness and then yielding to dissipate energy from the input loading and protect the remaining portions of the structure from damage. In this research, a series of large-scale hybrid simulation tests were performed to investigate the seismic performance of the self-centering rocking steel frame and in particular, the ability of the controlled rocking system to self-center the entire building. The hybrid simulation experiments were conducted in conjunction with computational modules, one that simulated the destabilizing P-Δ effect and another module that simulated the hysteretic behavior of the rest of the building including simple composite steel/concrete shear beam-to-column connections and partition walls. These tests complement a series of quasi-static cyclic and dynamic shake table tests that have been conducted on this system in prior work. The hybrid simulation tests validated the expected seismic performance as the system was subjected to ground motions in excess of the maximum considered earthquake, produced virtually no residual drift after every ground motion, did not produce inelasticity in the steel frame or post-tensioning, and concentrated the inelasticity in fuse elements that were easily replaced. Copyright © 2014 John Wiley & Sons, Ltd.

57 citations


Journal ArticleDOI
TL;DR: Yokohama Bay Bridge, with a total span length of 860 m, is the second longest span cable-stayed bridge in East Japan, and one of the most densely instrumented bridges in Japan as mentioned in this paper.
Abstract: Yokohama Bay Bridge, with a total span length of 860 m, is the second longest span cable-stayed bridge in East Japan, and one of the most densely instrumented bridges in Japan. On March 11, 2011, the Great East Japan (Tohoku) Earthquake hit northeastern Japan with magnitude of MW 9.0, notably the largest earthquake in Japan’s modern history. Intensity 5+(PGA 1.4–2.5 m/s2) of the maximum scale 7 of Japan Meteorogical Agency’s seismic intensity was recorded on the bridge site. This paper describes seismic response analyses of the bridge, system identification, performance evaluation of link-bearing connections (a seismic isolation system), and postearthquake field observation. Response analyses show that transverse vibration dominated the response of girder and tower, with a maximum girder displacement of 62 cm. The large transverse vibrations induced pounding between tower and girder on the tower–girder connections as shown by the periodic impulses on acceleration records. Meanwhile, longitudinal accelerations indicate that the link-bearing connections functioned properly during the earthquake. System identification reveals nonlinearity of the response as evidenced by variations in natural frequencies and mode shapes during large excitation. Despite these conditions, the bridge did not suffer any structural damages, since the ground motions experienced during the earthquake were less than the design and seismic retrofit ground motions.

46 citations


Journal ArticleDOI
TL;DR: In this paper, the authors proposed a bidirectional pushover analysis (BPA) method to overcome the limitations of current pushover methods to assess the seismic response of irregular (both in plan and in elevation) buildings subjected to biddirectional ground motions.
Abstract: Pushover analysis is one of the most-used nonlinear static procedures for the seismic assessment of structures; therefore, nowadays it is extensively used by practicing engineers for the seismic analysis of virtually every type of building. This paper proposes a bidirectional pushover analysis (BPA) method to overcome the limitations of current pushover methods to assess the seismic response of irregular (both in plan and in elevation) buildings subjected to bidirectional ground motions. The extended N2 method and the proposed BPA method were applied to estimate the nonlinear response of six highly irregular reinforced concrete frame structures designed according to the requirements of Eurocode 8. Results in terms of interstory drifts and floor rotations are compared with those given by nonlinear response history analysis (NRHA). For the latter, a suite of twenty Italian bidirectional seismic ground motions was selected. It was found that results given by the proposed BPA method match those given ...

42 citations


Journal ArticleDOI
TL;DR: In this article, the authors present the field observations on the seismic performance of precast concrete structures during the 2011 Van earthquake and another major earthquake with a magnitude of 5·6 occurred on 9 November 2011.
Abstract: A destructive earthquake, magnitude of Mw = 7·2 (Richter scale), hit the city of Van, located in eastern Turkey, on 23 October 2011 and another major earthquake with a magnitude of Mw = 5·6 occurred on 9 November 2011. Significant damage was observed in all types of civil engineering structures in the city centre and nearby. This paper presents the field observations on the seismic performance of precast concrete structures during the earthquakes. Possible damaging factors were discussed in detail after a comprehensive site survey. The majority of the investigated structures were industrial precast concrete structures located in the organised industrial zone of Van. In addition to industrial precast concrete structures, a precast multi-storey residential building located in the city centre was also examined. The findings from the site investigations were compared with the seismic behaviour of similar precast concrete structures during the former devastating earthquake in north-western Turkey in 1999. The ...

40 citations


Journal ArticleDOI
TL;DR: In this article, the conceptual design of an innovative seismic-resistant steel framing system capable of providing stiffness and ductility to new or existing structures is presented, which consists of concentric X-braces connected in series with rectangular sacrificial shear panels.
Abstract: The conceptual design of an innovative seismic-resistant steel framing system capable of providing stiffness and ductility to new or existing structures is presented. The bracing system consists of concentric X-braces connected in series with rectangular sacrificial shear panels. The braces are designed to remain elastic during seismic events while the shear panels are sized and configured to dissipate ample energy through plastic deformation-induced stable hysteretic behavior. Detailed three-dimensional nonlinear finite-element analyses using ABAQUS are performed to characterize and quantify the effects of the design parameters on the local response of the bracing system and to adjust the design so that potential buckling of the elements is mitigated. The finite element predicted force-displacement curves of bracing systems that achieve the desired local behavior when subjected to a specified interstory drift are in turn translated into a SAP2000 nonlinear link element. Embedment of the link elem...

38 citations


Journal ArticleDOI
TL;DR: In this paper, a parametric study of global bridge response demonstrates that the anchorage of fixed bearings to substructures could be reduced to limit the damage to the supporting substructure unit while incurring only a nominal increase in superstructure displacement demands.
Abstract: Steel fixed bearings are commonplace structural elements for transmitting loads from superstructures to substructures, and they have typically occupied a role of elastic force transfer elements within the overall scheme of an earthquake resisting system (ERS). Recent revisions to design and guide specifications have acknowledged the possibility of bearings acting as fuses, but there is little research available to characterize bearing behavior for such design roles or the associated bridge response to be expected when bearings have fused. One design approach, adopted by the Illinois DOT (IDOT), applies capacity design principles and permits the bearings and superstructure to slide on the substructure. The intent of this design approach is to capture some of the beneficial aspects of conventional isolated systems, such as period elongation, reduction of force demands, and protection of substructures from large inelastic displacement demands, without incurring the additional design provisions and fabrication costs to satisfy the requirements for seismic isolation systems. To achieve this quasi-isolated bridge response, steel fixed bearings are used as fusing elements, where the steel pintles or anchor rods rupture, and the fixed bearing plates become free to slide on the supporting pier cap. A properly proportioned bearing will fuse prior to superstructure/substructure elements experiencing inelastic demands. The University of Illinois has been collaborating with IDOT to investigate the behavior of quasi-isolated bridge systems and to calibrate and refine IDOT’s ERS design and construction methodology. The research is composed of experimental testing to characterize fundamental bearing behavior, coupled with nonlinear global bridge modeling to evaluate limit state progression and estimate maximum displacement demands of the superstructure relative to the substructure. The cyclic response of full-scale steel low-profile fixed bearings demonstrates predictable sliding behavior, but based on current design procedures, these bearings are often overdesigned for use as fuses in quasi-isolated bridges. Consequently, a bridge, which in other respects may exhibit satisfactory quasi-isolated response, might also incur significant damage to the substructure unit where fixed bearings are provided. A parametric study of global bridge response demonstrates that the anchorage of fixed bearings to substructures could be reduced to limit the damage to the supporting substructure unit while incurring only a nominal increase in superstructure displacement demands.

29 citations



Journal ArticleDOI
TL;DR: In this paper, the earthquake performance of concrete gravity dams under spatially variable seismic excitations was investigated using a nonlinear finite element model, which is then subjected to spatially varying earthquake ground motions incorporating the wave passage effect, with values for apparent propagation velocities consistent with the source site geometry and the shear wave velocity in the foundation rock.
Abstract: This paper investigates the earthquake performance of concrete gravity dams under spatially variable seismic excitations. A nonlinear finite element model is developed and validated using shake table experimental results. The model is then subjected to spatially varying earthquake ground motions incorporating the wave passage effect, with values for apparent propagation velocities consistent with the source-site geometry and the shear wave velocity in the foundation rock. The evaluation reveals that different response patterns occur when spatially non-uniform and uniform seismic ground motions are applied as input excitations to the model, because spatially non-uniform excitations induce the quasi-static response, whereas uniform excitations do not, and, in addition, the dynamic response caused by different input motions varies. Notably, spatially non-uniform excitations produce larger opening at the heel of the dam and severer slipping at its toe; this latter observation can have a significant effect on ...

19 citations


Journal ArticleDOI
01 Jul 2014
TL;DR: In this paper, the effects of SSI on the seismic response of multi-story buildings are analyzed for a typical building resting on a raft foundation, and three methods of analysis are used for seismic demands evaluation of the target moment resistant frame buildings: equivalent static load (ESL), response spectrum (RS) methods and nonlinear time history (TH) analysis with suit of nine time history records.
Abstract: The investigation on the energy transfer mechanism from soils to buildings during earthquakes is critical for the design of earthquake resistant structures and for upgrading existing structures. Thus the need for research into Soil-Structure Interaction (SSI) problems is greater than ever. Moreover, recent studies show that the effects of SSI may be detrimental to the seismic response of structure and neglecting SSI in analysis may lead to un-conservative design. Despite this, the conventional design procedure usually involves assumption of fixity at the base of foundation neglecting the flexibility of the foundation, the compressibility of soil mass and consequently the effect of foundation settlement on further redistribution of bending moment and shear force demands. Hence the soil-structure interaction analysis of multi-story buildings is the main focus of this study; the effects of SSI are analyzed for typical multi-story building resting on raft foundation. Three methods of analysis are used for seismic demands evaluation of the target moment resistant frame buildings: equivalent static load (ESL); response spectrum (RS) methods and nonlinear time history (TH) analysis with suit of nine time history records. Three-dimensional FEM model is constructed to analyze the effects of different soil conditions and number of stories on the vibration characteristics and seismic response demands of building structures. Numerical results obtained using soil structure interaction model conditions are compared to those corresponding to fixed-base support conditions. The peak responses of story shear, story moment, story displacement, story drift, moments at beam ends, as well as force of inner columns are analyzed. The analysis results of different approaches are used to evaluate the advantages, limitations, and ease of application of each approach for seismic analysis.

Journal ArticleDOI
TL;DR: In this article, a novel steel damper for bridges is presented, which employs steel plates as energy dissipation components, and adopts a vertical free mechanism to achieve a large deformation capacity.
Abstract: Isolation bearings and dampers are often installed between piers and superstructures to reduce the seismic responses of bridges under large earthquakes. This paper presents a novel steel damper for bridges. The damper employs steel plates as energy dissipation components, and adopts a vertical free mechanism to achieve a large deformation capacity. Quasi-static tests using displacement-controlled cyclic loading and numerical analyses using a finite element program called ABAQUS are conducted to investigate the behavior of the damper, and a design methodology is proposed based on the tests and numerical analyses. Major conclusions obtained from this study are as follows: (1) the new dampers have stable hysteresis behavior under large displacements; (2) finite element analyses are able to simulate the behavior of the damper with satisfactory accuracy; and (3) simplified design methodology of the damper is effective.

01 Jan 2014
TL;DR: In this article, the authors present the various limitations in design and construction practices along with the feedback to overcome the limitations and make the structures safer to take the earthquake forces, focusing on software used in the civil engineering for analysis and design, construction methods/practices, use of materials, types of structures, experiments for earthquake studies, quality control parameters etc.
Abstract: The paper presents the various limitations in design and construction practices along with the feedback to overcome the limitations and make the structures safer to take the earthquake forces. The paper focuses on software used in the civil engineering for analysis and design, construction methods/practices, use of materials, types of structures, experiments for earthquake studies, quality control parameters etc.

01 Jan 2014
TL;DR: In this article, a dynamic analysis of G+12 multistoried RCC building considering for Koyna and Bhuj earthquake is carried out by time history analysis and response spectrum analysis and seismic responses of such building are comparatively studied and modeled with the help of ETABS software.
Abstract: Earthquakes occurred in recent past have indicated that if the structures are not properly designed and constructed with required quality may cause great destruction of structures. This fact has resulted in to ensure safety against earthquake forces of tall structures hence, there is need to determine seismic responses of such building for designing earthquake resistant structures by carrying seismic analysis of the structure. Time history analysis is one of the important techniques for structural seismic analysis especially when the evaluated structural response is nonlinear. In the present work dynamic analysis of G+12 multistoried practiced RCC building considering for Koyna and Bhuj earthquake is carried out by time history analysis and response spectrum analysis and seismic responses of such building are comparatively studied and modeled with the help of ETABS software. Two time histories (i.e. Koyna and Bhuj) have been used to develop different acceptable criteria (base shear, storey displacement, storey drifts).

Journal ArticleDOI
TL;DR: In this article, the seismic analysis and retrofit of a prestressed reinforced concrete bridge is discussed by considering a real case of a viaduct still in use and the results of the analysis indicate that the structural performance can be enhanced by only modifying the support devices.

Journal ArticleDOI
TL;DR: The poor seismic performance of schools has made their assessment and retrofit a priority in moderate and high seismic zones as mentioned in this paper, and given the large building inventory to evaluate, rapid seismic screening has been proposed.
Abstract: The poor seismic performance of schools has made their assessment and retrofit a priority in moderate and high seismic zones. Given the large building inventory to evaluate, rapid seismic screening...

Proceedings ArticleDOI
25 Mar 2014
TL;DR: In this article, the results from a test conducted at the University of Colorado at Boulder have been summarized to evaluate seismic soil-structure interaction, lateral seismic earth pressures, and dynamic response of equivalent model structures representing buried water reservoirs during a selected suite of input earthquake motions.
Abstract: This paper summarizes the results from a centrifuge experiment conducted at the University of Colorado at Boulder to evaluate seismic soil-structure interaction, lateral seismic earth pressures, and dynamic response of equivalent model structures representing buried water reservoirs during a selected suite of input earthquake motions. This paper presents a summary of the design and planning, instrumentation challenges, and test results for the first baseline experiment in a series of centrifuge tests. The preliminary results indicate that underground structures similar in type to those tested in this study can experience seismic lateral earth pressures of engineering importance. The insight from these tests is useful for understanding the performance of underground reservoir structures worldwide and is applicable to an entire class of unyielding underground structures that are restrained at their roof and floor levels.

Journal ArticleDOI
TL;DR: In this paper, the technical advantages of substituting ultralightweight slab materials like cross-laminated-timber (CLT) for reinforced concrete (RC) floors and roofs of low-rise and high-rise hybrid building superstructures are presented.
Abstract: Design analyses are presented to demonstrate the technical advantages of substituting ultralightweight slab materials like cross-laminated-timber (CLT) for reinforced concrete (RC) floors and roofs of low-rise and high-rise hybrid building superstructures. Such substitution reduces the gravitational masses of slab by at least two-thirds without reducing functionality as bending or diaphragm slabs. Specific illustrations of design impacts of using CLT are given for hybrid building superstructures where steel or RC frameworks are the primary means of resisting effects of gravity forces associated with occupied built spaces. Results shown apply to two-story buildings in which effects of lateral forces associated with wind or seismic loads are resisted entirely by a steel moment framework, and six- and twenty four–story buildings in which RC shear walls within building cores primarily resist effects of such lateral loads. Consideration is also given to how fire engineering design decisions can impact ...

Journal ArticleDOI
B. Shan1, Yan Xiao1
TL;DR: In this paper, the axial loading creep behavior of fiber-reinforced plastic (FRP) reinforced concrete (RC) columns with different degrees of simulated earthquake damage is analyzed.
Abstract: Seismic retrofit of reinforced concrete (RC) columns using fiber-reinforced plastic (FRP) jacketing has been widely investigated. However, the residual performance of FRP retrofitted columns after surviving earthquake attacks remains as an issue with little research. As a follow up of a previous experimental study, this paper reports the analysis of the axial loading creep behavior of FRP retrofitted RC columns with different degrees of simulated earthquake damage. The damage degree and residual strains in FRP after lateral loading are assessed based on previous maximum lateral displacement excursion. A creep model for damaged columns with FRP jacket is presented based on the age-adjusted effective modulus method for creep of concrete and the Findley’s power law function for creep of FRP jacket. The creep model considers the effects of previous damage, sealed concrete, multiaxial stress state of stresses and stress redistribution. The proposed model is validated against previous creep tests of fiber-wrapped concrete columns by other researchers and the long-term tests conducted by the authors. Finally, a detailed study is carried out to identify the practical design parameters affecting creep of hybrid columns. The analytical results show that the creep of the FRP confined column increases as the damage degree becomes larger and exhibits notable nonlinear feature. The creep life declines and may cause creep rupture of the FRP when retrofitted columns suffer serious earthquake damage or under high axial load.

Journal ArticleDOI
TL;DR: In this paper, an investigation of high performance concrete (HPC) joints with conventional concrete (CC) joints (exterior beam-column) was performed by comparing various reinforcement detailing schemes.
Abstract: Recent earthquakes have demonstrated that most of the reinforced concrete structures were severely damaged; the beam-column joints, being the lateral and vertical load resisting members in reinforced concrete structures, are particularly vulnerable to failures during earthquakes. The existing reinforced concrete beam-column joints are not designed as per code IS13920:1993. Investigation of high performance concrete (HPC) joints with conventional concrete (CC) joints (exterior beam-column) was performed by comparing various reinforcement detailing schemes. Ten specimens were considered in this investigation and the results were compared: four specimens with CC (with and without seismic detailing), four specimens with HPC (with and without seismic detailing), and two specimens with HPC at confinement joint. The test was conducted for lateral load displacement, hysteresis loop, load ratio, percent of initial stiffness versus displacement curve, total energy dissipation, strain in beam main bars, and crack pattern. The results reveal that HPC with seismic detailing will be better compared with other reinforcements details under cyclic loading and reverse cyclic loading.

Journal ArticleDOI
TL;DR: In this article, a new methodology for nonlinear dynamic analysis of the seismic performance of reinforced-concrete (RC) buildings considering the pile foundation-structure interaction is presented.
Abstract: At present, information on foundation-structure interactions of buildings is lacking. As a result, seismic performance evaluations of buildings seldom consider the effect of foundation performance on the building response. Recent destructive earthquakes, such as the Hokkaido Nansei-oki earthquake (magnitude M = 7.8, Japan, 1993), Northridge earthquake (M = 6.7, U.S.A., 1994), Hyogoken-Nambu earthquake (M = 7.2, Japan, 1995), Chi-Chi earthquake (M = 7.6, Taiwan, 1999), Niigata Chuetsu earthquake (M = 6.8, Japan, 2004), Sichuan earthquake (M = 7.9, China, 2008), and Tohokuchiho Taiheiyo earthquake (M = 9.0, Japan, 2011), have shown that building damage is significantly affected by the degree of damage sustained by the building foundation, and by the interaction between the building and its foundation. This paper presents a new methodology for nonlinear dynamic analysis of the seismic performance of reinforced-concrete (RC) buildings considering the pile foundation-structure interaction. The proposed method ...

Journal ArticleDOI
TL;DR: In this paper, a simplified method for the assessment of the seismic response and damage development analyses of an RC structural wall building using macro-element model was proposed. And the sensitivity of the predicted wall responses to changes in model parameters is also assessed.
Abstract: Numerical simulation of the non-linear behavior of (RC) structural walls subjected to severe earthquake ground motions requires a reliable modeling approach that includes important material characteristics and behavioral response features. The objective of this paper is to optimize a simplified method for the assessment of the seismic response and damage development analyses of an RC structural wall building using macro-element model. The first stage of this study investigates effectiveness and ability of the macro-element model in predicting the flexural nonlinear response of the specimen based on previous experimental test results conducted in UCLA. The sensitivity of the predicted wall responses to changes in model parameters is also assessed. The macro-element model is next used to examine the dynamic behavior of the structural wall building−all the way from elastic behavior to global instability, by applying an approximate Incremental Dynamic Analysis (IDA), based on Uncoupled Modal Response History Analysis (UMRHA), setting up nonlinear single degree of freedom systems. Finally, the identification of the global stiffness decrease as a function of a damage variable is carried out by means of this simplified methodology. Responses are compared at various locations on the structural wall by conducting static and dynamic pushover analyses for accurate estimation of seismic performance of the structure using macro-element model. Results obtained with the numerical model for rectangular wall cross sections compare favorably with experimental responses for flexural capacity, stiffness, and deformability. Overall, the model is qualified for safety assessment and design of earthquake resistant structures with structural walls.

Journal ArticleDOI
TL;DR: In this article, a comparison of two 4-storey reinforced concrete buildings designed as high ductility classes (DCH) and medium ductility class (DCM) upon a strong rock (ground type A, Eurocode 8 soil classification) according to the Eurocode8.
Abstract: Provision of ductility in the structures according to the modern design codes lead to more economic constructions, while safety levels reach higher rates. The philosophy is based into allowing some damage to occur in predetermined elements where enough ductility has been provided in order to ensure the member’s capacity during an earthquake. This research focuses on investigating optimum ductility provisions for buildings to achieve the desired performance. The aim is to assess the parameters which affect ductility demands and overall present a comprehensive methodology for evaluating the structural performance. Analytical work was based on the comparison of two 4-storey reinforced concrete buildings designed as high ductility class (DCH) and medium ductility class (DCM) upon a strong rock (Ground type A, Eurocode 8 soil classification)according to the Eurocode 8. For a fair comparison both buildings were designed to have same vibration frequencies in order to experience same energy release rates under a number of earthquakes with varied ground acceleration amplitudes and frequency spectrums. The main criteria for the comparison were: (i) the inter-storey drifts, (ii) the energy distribution among the floors, (iii) the structural damage in terms of plastic hinges initiation and ductility demand rates, (iv) total energy dissipation and (v) top floor displacements. The damage rates in the structures were found to be directly correlated to the earthquake’s frequency range. Low frequency seismic events corresponding to high periods in the elastic response spectrum used for the design of the structures were more catastrophic. The paper proved that DCH buildings perform generally better than DCM for high ground acceleration amplitudes, while for smaller GAA where the responses are governed by the stiffness in the elastic response range the DCM structures have functional superiority. Higher ductility provisions have been found beneficial for the structural performance, especially for higher ductility demands caused by higher intensity earthquakes with increased return periods and ground acceleration amplitudes.

01 Jan 2014
TL;DR: In this paper, the authors present a realistic analogy between green trees and manmade moment frames under similar loading conditions and introduce a new facet of bio-inspiration which attempts to benefit from some of the natural design strategies involved in the structural performance of trees, rather than utilizing them as raw materials.
Abstract: This article presents a realistic analogy, with practical applications, between green trees and manmade moment frames under similar loading conditions. The paper also introduces a new facet of bioinspiration which attempts to benefit from some of the natural design strategies involved in the structural performance of trees, rather than utilizing them as raw materials. The paper suggests that bioinspiration can help transfer and improve basic design concepts from trees to moment frames under seismic as well as gravity loading scenarios. For instance, it has been shown that earthquake resistant systems can best be realized by performing design led analysis rather than investigating analytic results and that structural design should be performance based rather than instruction oriented computations. In other words, it is preferable for earthquake resistant structures to be designed in accordance with observed rather than expected behavior, i.e., desirable response characteristics should be induced rather than investigated. These features constitute the core of the recently developed performance control (PC) methodology that aims at rational design of engineering structures under both service as well as extreme loading conditions. In the interim a number of new design formulae have also been introduced. Two examples have been provided to demonstrate the applications of the conceptual design similarities between green trees and earthquake resisting moment frames.

14 Oct 2014
TL;DR: In this article, the authors investigated the use of high strength reinforcement (HSS) for post-seismic operations of lifeline corridors in reinforced concrete (RC) columns.
Abstract: This project furthered the development of three strategies that could positively impact maintaining post-seismic operations of lifeline corridors. In Year 1, most of the focus was on the development of the three individual strategies. In Year 2, a follow-up project will include more formal assessments of the situation in which each strategy might be preferred. The first part of the investigation, performed at Oregon State University, assessed the use of high strength reinforcement (HSS) for use in reinforced concrete (RC) columns.HSS is not currently allowed in RC due to lack of information on the material characteristics and lack of performance information when used in columns. But potential benefits in construction, performance, and economics justify the need for research, especially for critical corridors. Results indicate that a column constructed with Grade 80 HSS reinforcement performs similar to column constructed with conventional Grade 60 reinforcement. The second part of the investigation, performed at the University of Washington, focused on a new type of connection between a precast concrete column and a cast-in-place drilled shaft. The column is precast with a roughened outer surface at the bottom of the column which will be embedded in the cast-in-place shaft. The connection can be built rapidly and allows generous construction tolerances. Building on two previous tests, a third quasi-static scaled connection test between a precast bridge column and a drilled shaft was performed to investigate the seismic performance of the new connection. The geometry of the test specimen was based on the minimum practical difference between the diameters of the shaft and the column, and so represented the most critical cases. The performance of the system was investigated up to a drift ratio of 10%. The experimental results showed that, if adequate confining steel is included in the splice zone, the plastic hinging mechanism forms in the column, without incurring damage in the splice zone or shaft. If the confinement is insufficient, the strength of the splice zone deteriorates rapidly with cyclic loading. Recommendations for transverse reinforcement in the transition area are provided to ensure desirable performance. The third part of the investigation, also performed at the University of Washington, focused on the performance of concrete filled steel tubes (CFST), with specific focus on connections to precast concrete piers and pile caps. CFSTs have the potential to improve performance in seismic events and decrease overall costs. CFSTs may be used for bridge piers, shafts, caissons, and columns, but their use is limited because American Association of State Highway and Transportation Officials (AASHTO) design specifications for CFSTs are dated and few validated, constructible connections exist. Part 3 of this report (Part 3) compares current CFST design provisions to experimental results, noting limitations and deficiencies. Improved provisions proposed for the AASHTO specifications and partly based on the American Institute of Steel Construction (AISC) provisions are summarized. CFST connections are also addressed. A foundation connection capable of developing the full composite capacity of a CFST was evaluated experimentally and initial study of CFST column-to-cap beam connections was conducted using numerical simulation. Both are effective in developing and transferring the full capacity of the CFST and are summarized.

Journal ArticleDOI
TL;DR: In this paper, a linear-elastic finite-element analysis of an isolated wall-footing system under estimated actual vertical and lateral forces is carried out, and a new tapered configuration is proposed in the bottom portion of walls with and without enlarged boundary elements.
Abstract: In multistoried RC wall-frame buildings, properly designed and detailed RC slender structural walls significantly improve earthquake resistance. In walls on isolated spread footings with marginal taper, severe stress concentration is observed at the wall-footing junction during earthquake shaking. In this paper, new tapered configurations are proposed in the bottom portion of walls with and without enlarged boundary elements. Analytical correlations are derived among salient structural and soil parameters of the tapered wall-footing. An extensive parametric study is carried out through linear-elastic finite-element analysis of an isolated wall-footing system under estimated actual vertical and lateral forces. Under the estimated forces, significant loss of contact is observed at the bottom of the wall-footing; thus, soil or rock anchors need to be provided to ensure stability of the wall-footings during strong shaking. Force flow from wall to footing improves significantly in the proposed integrat...

Journal Article
TL;DR: In this paper, the authors took the topic about Sriwijaya University dorm building with lateral resistant combined moment resisting frame system and shearwall and the result is dimension and rebar reinforcement of the struktural elements.
Abstract: Indonesia is an earthquake prone areas, t o reduce the risk of the disaster required the construction of earthquake resistant buildings . The structure usually design base on the elastic analysis that would be multiplied by load factor to simulate the ultimate condition. Actually , the behavior of building subject to seismic load s are in-elastic . Concrete structure is the most commonly material in the construction. In high-rise buildings quake resistant, generally the forces at column is enough to resist the quake loads so need to use rigid structural elements such as shearwall to resist combined shear force, moment and axial force due to earthquake . With using shearwall, the majority of quake loads will be absorbed by shearwall. This essay took the topic about Sriwijaya University dorm building with lateral resistant combined moment resisting frame system and shearwall . Building were designed according to SNI 03-2847-2002 and SNI 03-1726-2002. From the result of the calculation have been done, the result is dimension and rebar reinforcement of the struktural elements. Beam dimension 25 x 40 cm, column dimension 40 x 40 cm, slab thickness 16 cm and shearwall thickness 25 cm. Joint displacement deviation due to x axis quake load and y axis quake load is 5,52 mm and 5,71 mm, where that result not exceed service limit and ultimate limit of building.  Key Words : earthquake , concrete , lateral resistant, mrfs, shearwall


Dissertation
28 Nov 2014
TL;DR: In this paper, both impedance and transfer functions were developed with the aim of providing improved response spectrum, as a key engineering tool for design of earthquake resistant structures, and proposed methodology for including the developed functions into classical program packages mostly used by engineering practice and academia for structural analysis and design.
Abstract: This thesis deals with seismic response of shallow founded structures on soft soils. Research within the thesis is initiated with the main assumption that the European code-based response spectra for soft soils are ill-defined and that they do not include soil-structure interaction effects. With the aim to provide improved response spectrum, as a key engineering tool for design of earthquake resistant structures, both impedance and transfer functions were developed. Those functions enable incorporation of both soil compliance and its capability that dissipates earthquake energy. Parametric study was conducted using numerical models calibrated with regards to experimental results obtained both from testing performed in enhanced gravitational field using geotechnical centrifuge at the IFSTTAR institute and on shaking table of the University of Bristol at 1g. Numerical modelling, and thus parametric study, was governed using equivalent linear method. The last chapter of the work provides proposed methodology for including the developed functions into classical program packages mostly used by engineering practice and academia for structural analysis and design. Also, proposal for application of impedance functions within the framweork of N2 method is provided.

Proceedings ArticleDOI
09 Apr 2014
TL;DR: In this paper, displacement-based seismic design concepts are used to satisfy the performance objectives of both the IBC and AASHTO codes, without producing a design that is overly conservative.
Abstract: As energy costs soar, public demand for massive transportation systems has increased. Massive transportation systems often include structures such as station buildings that are linked by elevated bridges. It is essential for these aerial structures to withstand large earthquakes. Structural engineers typically design station buildings according to the IBC which references ASCE 7, while bridge design is based on the American Association of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO LRFD) bridge design code and the Guide Specification for seismic design. IBC and AASHTO LRFD both use force-based design, but with different spectral loads, analysis parameters, and levels of acceptance. The newly published AASHTO Seismic Guide Specification applies displacement-based seismic design as its framework. However, there is no unified code for the seismic design of this kind of mixed structural systems in the United States. How will these codes be implemented in the design of mixed structural systems without violating either code? Based on displacement-based seismic design concepts, this paper uses a case study to show how the seismic design of mixed structural systems can satisfy the performance objectives of both the IBC and AASHTO codes without producing a design that is overly conservative.