- Design of the Unreinforced Masonry Shear Wall Resistance in the High Seismic Areas. Case Study
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- Book Title / Journal:
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: shear strength
- Description
- Because of diagonal cracking failure (due to main tensile stresses as the main failure criterion) of the unreinforced masonry shear walls subject to lateral in-plane forces and eccentric compression, it is very important to evaluate the capacity of the shear resistance and to perform the strength request verification in the critical section of the wall.
In the Romanian Codes, capacity of shear resistance of the wall (VRd) is calculated at modified ULS, by limiting tensile length zone, at eccentric compression. Although the numbers of levels are sever reduced with this method is difficult to respect the strength request.
In Romania was realized another methodology (authors: G&R Popescu), with capacity of shear resistance evaluated taking into account the principal failure by diagonal cracking, according with the materials resistance theory. The values of (VRd) are close with those obtained from tests. Case Study contains walls calculated with the two methods.
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- Inelastic Seismic Response of Reinforced Concrete Buildings with Symmetric and Unsymmetric Floor Diaphragm Openings
- M.T. Al Harash ; N. Panahshahi
- Book Title / Journal: 15th World Conference on Earthquake Engineering
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: inelastic response ; concrete buildings
- Description
- Floor and roof diaphragms play a key role in distributing earthquake-induced loads to the lateral load resisting systems. The in-plane flexibility of the diaphragms was often ignored for simplicity in practical design, until recently where building standards such as ASCE7 (2005) acknowledged that this assumption can result in considerable errors when predicting the seismic response of RC buildings with diaphragm plan aspect ratio greater than 3:1. However, the influence of floor diaphragm openings has not been directly considered. In this paper, the inelastic seismic response of five 3-story reinforced concrete buildings with end shear walls and plan
aspect ratio of 4:1 with symmetric and unsymmetric floor openings within the middle two-thirds of the building using an enhanced version of IDARC2 are presented. It is concluded that the influence of “inelastic” in-plane diaphragm deformations due to floor openings may not be overlooked when openings are present irrespective of where they are located.
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- Study on Shaking-Table Experiment of a Full-Scale Four-Story Steel Building
- T. Tuan-Nam ; K. Kasai
- Book Title / Journal: 15th World Conference on Earthquake Engineering
- Year: 2012 , Volume: , Series:
- Structure types ; Steel structures ; Earthquake engineering
- Keywords: E-Defense shaking-table ; numerical analysis ; collapse experiment ; local buckling ; incremental dynamic analysis
- Description
- This paper presents the dynamic collapse analysis of a full-scale four-story steel building which was
experimented to collapse at the E-Defense shaking-table in Japan, in 2007, using the ground acceleration histories recorded at the JR Takatori station during the 1995 Hyogo-ken Nanbu earthquake. Deterioration of columns on the first story level due to local buckling is thought to be one of major reasons for the building collapse. Fiber method approach is adopted in the analysis to simulate local buckling at the column ends. Hypothetical analyses estimate the collapse capacity of the building specimen at approximately 0.9 times Takatori ground motion level. The collapse capacity of the building specimen under various propagating directions of the non-scaled Takatori ground motion is also investigated, showing that the building likely collapses under any propagating direction of the ground motion.
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- Experimental Study of the Behaviour of a New Replaceable Bracing System (BBBS)
- S.V. Khonsari ; M. Moradi ; D. Zarei ; H. Farahani ; G.L. England
- Book Title / Journal: 15th World Conference on Earthquake Engineering
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: Structural Bracing Systems ; Replaceable Bracings ; Cyclic Loading ; Energy Dissipation ; Retrofitting
- Description
- A new bracing system with new features somewhat different from those of the existing ones was devised and is presented. These features comprise some of the advantages of eccentric bracing systems including their ability to dissipate energy through bending of flexural elements while lacking some of the disadvantages of such systems
including their inability of being replaced upon damage during events such as earthquakes, etc. While in traditional types of braces, including both concentric and eccentric ones, braces are under axial loading, in this new system they work in a bending capacity. As a result, the sort of flexibility which is introduced in the system in the presence of eccentric braces (definitely at the price of forcing the potential damage to occur and be concentrated at the girders/beams to which such braces are connected), is now provided by the braces and at the price of sacrificing them. Therefore, if the level of damage is such that the damaged element is no longer usable, the replacement of the braces is a more viable and economically justifiable than that of the girders. Moreover, since girders, as part of the deck/floor system, are normally engaged with other elements such as stringers/joists, their replacement may not be practically possible at all. Such bracing systems, called Broken Beam Bracing System (BBBS), have the potential of being used in building as well as industrial structures as originally-used
elements or in a retrofit/repair capacity.
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- Comparison of the Seismic Performance of Equivalent Straight and Curved Bridges due to Transverse Seismic Excitation
- E. Khan ; M.J. Kowalsky ; J.M. Nau
- Book Title / Journal: 15th World Conference on Earthquake Engineering
- Year: 2012 , Volume: , Series:
- Bridge management ; Bridges ; Earthquake engineering
- Keywords: Direct Displacement Based Design ; Bridges ; Transverse Seismic Design of Curved Bridge
- Description
- This study compares the transverse response of equivalent straight and curved bridges to investigate the hypothesis made by the AASHTO Guide Specification for LRFD Seismic Bridge Design that curved bridges may be analyzed as if they are straight, provided the bridge is regular. For this purpose curved bridges with subtended angles of 15, 30, 45, 60, 75, and 90 degrees, having the total arc length equal to the length of the equivalent straight bridge, are considered. Other parameters considered in this study are the number of spans
(two, four and six), and abutment restraints (9 different conditions). The equivalent straight bridges are designed using the Direct Displacement Based Design (DDBD) procedure including these parameters. The resulting designs are then analyzed with Inelastic Time History Analysis using both straight and curved geometry. Each bridge was subjected to 7 spectrum compatible time histories. Individual as well as average results are tabulated.
It is observed that deviation in the response of the curved bridge from the equivalent straight bridge increases as the subtended angles become larger and the number of spans reduces. It was also found that the type and degree of abutment restraint is a rather critical parameter in controlling the response of the bridge, the most significant being longitudinal abutment restraint which had a profound impact on results.
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- Seismic Performance Assessment of Buildings_Vol.1
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- Book Title / Journal:
- Year: 2012 , Volume: 1 , Series:
- Earthquake engineering
- Keywords: Seismic performance ; buildings
- Description
- This report describes a general methodology and recommended procedures to assess the probable seismic performance of individual buildings based on
their unique site, structural, nonstructural, and occupancy characteristics. Performance is measured in terms of the probability of incurring casualties,
repair and replacement costs, repair time, and unsafe placarding. The methodology and procedures are applicable to new or existing buildings, and
can be used to: (1) assess the probable performance of a building; (2) design new buildings to be capable of providing desired performance; or (3) design seismic upgrades for existing buildings to improve their performance.
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- Seismic Performance Assessment of buildings_Vol.2
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- Book Title / Journal:
- Year: 2012 , Volume: 2 , Series: FEMA P-58-2
- Earthquake engineering
- Keywords: seismic assessment ; buildings
- Description
- This report provides guidance on implementing the seismic performance assessment methodology set forth in FEMA P-58-1, Seismic Performance
Assessment of Buildings, Volume 1 – Methodology, to assess the seismic performance of individual buildings based on their unique site, structural,
nonstructural, and occupancy characteristics, expressed in terms of the probability of incurring casualties, repair and replacement costs, repair time, and unsafe placarding. This Implementation Guide contains examples illustrating the performance assessment process, including selected
calculation and data generation procedures, as well user manuals for selected electronic materials provided in Volume 3 – Supporting Electronic Materials and Background Documentation.
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- 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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