- A New Procedure for Selection and Modification of Ground Motion for Nonlinear Dynamic Analysis Strong Ground Motion for Nonlinear Dynamic Analysis
- M. Nooraie ; F. Behnamfar
- Book Title / Journal: Proceedings of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: ground motion selection and modification ; Nonlinear dynamic analysis
- Description
- Nonlinear dynamic analysis is known as the most accurate method to evaluate the behavior of structures during an earthquake. In this context, the selection process of suitable records and their modification plays a vital role. An effective selection and modification of ground motion as the loads to be used in the analysis can lead to responses with low dispersion in nonlinear structural analysis. This in turn, results in much more trust in the safety of the designed structure. This fact highlights the importance of the current study. Screening process is a three-stage operation as the Coarse, Medium, and Fine-Screen sub-processes. The remaining records are modified in order to minimize the scatter in the results of nonlinear dynamic analysis of the structure under study, by calculating scale factors by different methods to be multiplied to the selected earthquake time histories. The proposed method results in least scatter in representative nonlinear dynamic response quantities.
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- Assessment of the effect of in-cycle degradation in behavior of mid-rise steel moment frames
- P.N. Lahiji ; G.H. Ghodrati Amiri ; E. Darvishan
- Book Title / Journal: Proceedings of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: In-cycle strength degradation ; incremental dynamic analysis ; Steel moment frame
- Description
- For many years, providing sufficient strength of buildings to avoid collapse prevention was the most important purpose in seismic codes. Nowadays, in-cycle strength degradation attracts the attention of many researchers as a real phenomenon. Recent investigations have shown that the effects of in-cycle strength degradation can be critical in determining the possibility of lateral dynamic instability in SDOF systems. In this research these
effects in multi-degree-of-freedom (MDOF) structures have been evaluated by modeling 3, 5 and 7 story steel moment frame buildings with three types of connections (Pre-Northridge, Post-Northridge and Elastic-Perfectly-Plastic). By performing incremental dynamic analysis (IDA), effects of in-cycle strength degradation in instability of structures have been studied. Results of this study have shown that in-cycle strength degradation can highly increase the dynamic global instability of the steel moment frame structures.
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- Development of a seismic damage assessment methodology for building in Algeria
- M. Boukri ; M.N. Farsi ; M- Belazougui ; A. Mebarki ; S. Jerez
- Book Title / Journal: Proceedings on the 15th World Conference on Earthquake Engineering, Lsbon, Portugal
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: HAZUS ; Boumerdès earthquake ; Algerian Seismic Code
- Description
- Algeria is one of the countries that have experienced several strong to moderate earthquakesduring the last three decades. These earthquakes have caused considerable damages especially in the urban areas close to the epicentres. These damages can be reduced in urban areas prone to earthquakes if we proceed to estimate the seismic risk in sufficient time in order to take adequate preventive measures. In this paper is presented a seismic damage loss estimation methodology of buildings in Algeria based on the "Capacity Spectrum Method" using HAZUS(Hazard-United States) capacity and fragility curves adapted to the Algerian built context. This methodology gives an estimation of the seismic damage probabilities. A data-processing code was developed for this purpose to analyse the whole data and damage assessment. This methodology was validated with the observed damages induced by the May 21st,2003 Boumerdès earthquake.
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- Modal pushover-based scaling of records for nonlinear RHA of one-story unsymmetric-plan buildings
- J.C. Reyes ; O.A. Quintero ; A.K. Chopra
- Book Title / Journal: Proceedings of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: ground motion record ; pushover ; nonlinear RHA ; amplitude scaling
- Description
- The modal-pushover-based-scaling (MPS) procedure, currently restricted to symmetric-plan buildings, is extended herein to unsymmetric-plan buildings. The accuracy of the extended MPS procedure was evaluated for a large set of three-degree-of-freedom unsymmetric-plan structures with variable stiffness and strength. The structures were subjected to nonlinear response history analysis considering sets of seven records scaled according to the MPS procedure. Structural responses were compared against the benchmark values, defined as the median values of the engineering demand parameters (EDPs) due to 30 unscaled records. This evaluation of the MPS procedure has led to the following conclusions: (1) The MPS procedure provided a highly accurate
estimate of the median EDPs and reduced the record-to-record variability of the responses. (2) The MPS procedure is found to be much superior compared to the ASCE/SEI 7-05 scaling procedure for three-dimensional analysis.
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- Seismic Assessment of a 15-Story Building Damaged in the Chile Earthquake of February 27th 2010
- M. Kohrangi ; T.J. Sullivan ; G.M. Calvi
- Book Title / Journal: Proceedings of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: seismic assessment ; Chile earthquake
- Description
- This paper considers the seismic assessment of a 15-storey RC structural wall building, Alto Rio,
located in the city of Concepción that collapsed in the M8.8 Chile earthquake of Feb 27th 2010. Different methods of assessment, based on FEMA356, are applied to examine if the observed damage could have been anticipated. Results show that FEMA356 assessment methods would have identified that the building was likely to be damaged in a major earthquake. Severe irregularities and discontinuity of walls at the base of the structure, in general, and lack of ductile detailing in walls and coupling beams are identified as the likely reasons for the damage. In addition to this assessment, the design procedures that are expected to have been used for the original design of the building are reviewed. The results showed that in applying the code design procedure, wall axial tensile forces were probably underestimated and improved capacity design procedures should be implemented.
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- Seismic Design of Cable-stayed Bridges. The South Crossing Bridge in Guayaquil, Ecuador
- G.M. Calvi ; M. Moratti ; A. Villani ; D. Pietra ; R. Pinho
- Book Title / Journal: Proceedings of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: Cable-Stayed Bridges ; Seismic Design ; Viscous Damper
- Description
- Seismic design of long-span Cable-Stayed bridges has received a strong input in the latest decades, from both conceptual design and construction point of view, thanks to latest examples of design and
realizations of long-span Cable-Stayed bridges in high seismic areas where some of them have already
proved the success of the newly adopted conceptual designs. Within the proposed approach, the structural performance is ensured through the adoption of passive dissipation devices together with structural configurations substantially new for such kind of bridges. The confidence gained towards
this innovative approach for seismic protection of long-span bridges further promotes the attempt to
adopt those challenging structures as means for bridging morphological and economical gaps which
for long time have distressed the natural evolution of commercial flows and economical growth of entire countries, particularly of those highly prone to natural hazards such as earthquakes. The paper
illustrates the case study of the South Crossing Bridge in Guayaquil, Ecuador, from preliminary evaluations till the final design solutions adopted for its seismic protection.
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- Seismic Behavior of New Visco Plastic Device Equipped with Stell Cores and Viscoelastic Solid
- A.B. Sheikholeslami ; F. Behnamfar
- Book Title / Journal: Proceedings of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: Visco-plastic device ; steel cores ; passive energy dissipation
- Description
- This paper presents the preliminary results of an analytical and finite element investigation into the effectiveness of a new Visco-Plastic energy dissipation device. This new device, which is fabricated from readily available structural steel rods and viscoelastic solids, has a wide range of application in building and bridge structures. Input energy due to seismic excitation is dissipated by yielding of steel cores and shear strain in viscoelastic layer. One of the important abilities of the proposed energy dissipating device is its good performance under cyclic loading and high speed of repair. This is such a manner that after an intermediate or strong earthquake without need of foreman and extra equipment, only with changing the ductile steel cores used in the device, the
repairing process of structure can be accomplished very fast.
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- Collapse Performance Evaluation of Reinforced Concrete Special Moment Frame Systems Special Moment Frame Systems Considering Soil–Structure Interaction
- F. Behnamfar ; S. Haghollahi
- Book Title / Journal: Proceedings of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: Seismic collapse performance ; soil-structure interaction ; push-over ; IDA
- Description
- This study investigates an application of FEMA P695 (ATC-63) methodology for assessing collapse performance of reinforced concrete (RC) structures including the effect of soil-structure interaction. The new generation of performance based design approaches consider the SSI as a direct concern in order to more realistically estimate the seismic performance of structures. In response, this study investigates the SSI effects on seismic performance from within the framework of collapse performance evaluation of a medium height (eight-story) RC special moment frame structure. Comparison with similar studies on fixed-base counterparts results in prescribing conditions for how collapse evaluation should be implemented with SSI taken into account. In this paper the effect of SSI on the collapse behavior of the RC structure is illustrated by both pushover and IDA analysis in comparison with the fixed base structure.
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- Revision of IAEE Guidelines for Earthquake Resistant Non-Engineered Construction
- A.S. Arya ; T. Boen ; Y. Ishiyama
- Book Title / Journal: Proceedings of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: non-engineered construction ; masonry
- Description
- A large majority of houses and buildings in the world can be classified as non-engineered construction, e.g. (1) un-reinforced masonry, (2) confined masonry, (3) wooden construction, (4) earthen construction (adobe or tapial). Most of the loss of life in past earthquakes has occurred due to the collapse of these houses and buildings. Because of the continued use of such construction, it is essential to introduce earthquake resistant features in their construction. The International Association for Earthquake Engineering (IAEE) published the “Guidelines for Earthquake Resistant Non-Engineered Construction” in 1986. More than twenty years have passed since the publication and the guidelines are still used in many parts in the world, the revision of the guidelines was discussed among three of the committee members for the 1986 edition. The revision is going to be completed with the supports of UNESCO and the International Institute of Seismology and Earthquake Engineering (IISEE), JAPAN.
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- Benefits of Vertically Distributed Isolation Devices for an 8-storey Structure with Complex Geometry
- T.J. Sullivan ; A. Lago ; G.M. Calvi
- Book Title / Journal: Proceedings of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: complex geometry ; diagrid ; displacement based design ; visco-elastic damper
- Description
- The construction of structures with curved or irregular geometry is becoming increasingly common as modern architects strive to create iconic buildings. However, the realization of complex building forms creates significant challenges in regions of high seismicity, since this introduces significant uncertainties in the likely plastic mechanism, with questions on the likely performance of connections and doubts about the probable loadpaths. This paper examines the benefits of a novel seismic design strategy that uses isolation devices distributed vertically up a building between the exterior structure (of complex-geometry) and the heavy internal core. An innovative Direct DBD methodology is used to design an 8-storey case study building in which viscoelastic devices are used. Non-linear time-history (NLTH) analyses are then conducted on a 3-dimensional model of the building and the results indicate that the target displacement and drifts for both the internal and external structures are well controlled by the design solution.
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- Modeling of Sliding Shear Resistance of Reinforced Masonry Squat Walls
- J. Centeno ; C.E. Ventura ; S. Brzev
- Book Title / Journal: Proceedings of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: reinforced masonry ; sliding shear mechanism ; Seismic response
- Description
- This paper presents the results of an ongoing research study on the sliding shear mechanism in reinforced masonry (RM) shear walls. An overview is presented of the current design procedure and its limitations. Findings of previous studies have been used to develop an analytical model that will allow to simulate the sliding shear response of RM shear walls subjected to earthquake ground shaking in a realistic manner, comparable with the results of experimental studies. The proposed analytical model is described in this paper, and the preliminary results are compared with the results of relevant experimental studies.
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- Towards a Direct Displacement-Based Loss Assessment Methodology for RC Frame Buildings
- D.P. Welch ; T.J. Sullivan ; G.M. Calvi
- Book Title / Journal: Proceedings of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: displacement-based assessment ; simplified direct loss estimation ; RC frames
- Description
- Various loss assessment methodologies have been proposed and developed over the past few decades to provide risk assessment on a regional scale. There is an increasing need, however, to provide engineers with practical tools for building-specific loss assessment. Recently, progress has been made towards probabilistic building-specific loss models such as the PEER PBEE framework. However, as some consider that comprehensive probabilistic methodologies could be too complex for most practicing engineers, this paper presents a simplified probabilistic loss assessment methodology that builds on a direct displacement-based assessment framework. The simplified methodology attempts to incorporate critical aspects of comprehensive loss assessment models while maintaining a computational onus suitable for the design office. The trial methodology is tested via examination of a 4-storey RC frame building and encouragingly, the direct losses estimated by the new approach are found to be similar to those estimated by the PEER methodology.
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- Characteristics Affecting the Vulnerability of Soft Storey Mechanisms
- H.A. Beigi ; T.J. Sullivan ; G.M. Calvi ; C. Christopoulos
- Book Title / Journal: Proceedings of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: soft-storey ; post-yield stiffness ; concrete frame retrofit
- Description
- The seismic vulnerability of a six storey RC frame building typical of Italian construction practice from the 1970’s is examined in this work, initially considering two different infill configurations; the first considers full masonry infill and the second considers an open ground storey with full masonry infill above the first floor. Results of incremental dynamic analyses indicate that structures with uniform infill are less likely to collapse. However, it is also recognized that the need to retrofit structures with partial infill should depend on the seismic hazard and acceptable risk. Therefore, to provide insight into the factors affecting the vulnerability of such RC frame structures, the impact of P-Delta effects, post-yield stiffness ratio and ground storey column characteristics are investigated. Results are discussed and because p-delta effects and column axial load ratios are found to affect the vulnerability significantly, an innovative retrofit strategy that considers these characteristics is proposed.
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- Nonlinear Response-History Analysis of Triple Friction Pendulum Bearings (TFPB), Installed Between stories Pendulum Bearings (TFPB), Installed Between Stories
- F. Hamidreza ; G.A. Gholamreza
- Book Title / Journal: Proceedings of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: Triple Friction Pendulum Bearing ; inter-story isolation system ; multi-story isolation system
- Description
- In recent years, the damage to the well-designed structures, caused by earthquake, has attracted the attention of engineers to use adaptive seismic isolation systems such as Triple Friction Pendulum Bearings (TFPBs). An adaptive seismic isolator can exhibit different stiffness and damping during its course of motion and consequently award appropriate performance in different hazard levels. This paper investigates application of TFPBs in six stories steel frame structure, while TFPBs is installed at different levels; such as base, first story, third story or combination of them, and each state is compared with fixed-base and base isolated structure. The results indicate that base and first story isolation systems are extremely effective in reduction of maximum drift ratio and story shear force however this effect is diminished by increasing level of isolators. Additionally providing a second isolation level to base isolated structure, leads to a significant reduction in base deformation which is an adequate technique in presence of near-fault ground motion.
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- Analytically Derived Fragility Curves for Unreinforced Masonry Buildings in Urban Contexts
- D. D’Ayala ; E. Kishali
- Book Title / Journal: Proceedings of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: Vulnerability functions ; masonry ; performance based assessment
- Description
- Masonry buildings are the most common form of dwelling worldwide and at the same time one of the most vulnerable to seismic action. Large numbers of casualties and substantial economic losses are associated with masonry building partial and total collapses in urban and rural areas. Usually studies of vulnerability of masonry structures are conducted within an empirical framework, based on past observation and historic damage data. However empirical approaches have limitation in terms of regional applicability and comparison among different
typological and geographical context. The paper presents an analytical approach, FaMIVE, based on limit state analysis, which allows defining capacity curves and performance points for masonry structures. The analytical development of the procedure from derivation of the ultimate capacity to the identification of the damage states in terms of drift, to the convolution of the capacity and spectral curves to identify performance points for given level of shaking is presented. Fragility curves are then derived. An application to masonry structures in Turkey shows the advantages of this approach. This work was carried out within the framework of the WHE-PAGER project (http://pager.world-housing.net/)
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