scholarly journals A RATIONALIZED SEISMIC DESIGN METHOD FOR BUILDINGS IN EARTHQUAKE-PRONE DEVELOPING COUNTRIES

2021 ◽  
Vol 11 (4) ◽  
pp. 266-279
Author(s):  
Tint Lwin ◽  
Takeshi Koike ◽  
Ji Dang
Keyword(s):  
Developing Countries ◽  
Seismic Design ◽  
Design Method ◽  
Limit State ◽  
Design Procedure ◽  
Ultimate Limit State ◽  
Design Guideline ◽  
Seismic Safety ◽  
Seismic Design Method ◽  
Ultimate Limit

In general, the US codes such as the UBC-97 and ASCE-7 are widely used in developing countries including Myanmar, Syria, Philippines and so on. When the current seismic design guideline based on the UBC-97 and ACI 318-99 in Myanmar is assessed, several problems can be found in the following items: firstly, the fundamental period is not checked in modeling; secondly, reduction factor R is introduced a priori for the base shear estimation. And finally, a limit state assessment is done only for Design Basic Earthquake (DBE) but not for other design earthquakes. As a result, adequate yield strength is not checked for Maximum Operational Earthquake (MOE). Then there is no way to assess the seismic safety of the ultimate limit state for Maximum Considered Earthquake (MCE). In order to solve these problems, a rationalized seismic design method for earthquake prone developing countries is proposed. A new seismic design method is developed for MOE and MCE with adequate yield acceleration and typical period of the building estimated by using pushover analysis. A simplified procedure to estimate the inelastic response for a given design spectrum is also proposed. Finally, this design procedure can provide a rational method to assess the seismic safety for the ultimate limit of the building.

A proposed strategy for seismic design of steel buildings

1999 ◽  
Vol 26 (5) ◽  
pp. 564-571
Author(s):  
DJL Kennedy ◽  
M S Medhekar
Keyword(s):  
Seismic Design ◽  
Limit State ◽  
Evaluation Criteria ◽  
Design Procedure ◽  
Ultimate Limit State ◽  
Seismic Zone ◽  
Steel Buildings ◽  
Limit States ◽  
Design Earthquake ◽  
Ultimate Limit

The conceptual basis of the seismic design procedure in the National Building Code of Canada is reviewed. The design earthquake is specified only for the ultimate limit states at which the performance of both ordinary and important buildings is evaluated by an elastic static analysis in all zones. Criteria for checking the serviceability limit states, which apply to moderate earthquakes that may occur relatively frequently in the life of the building, are not specified explicitly. It is suggested that the current design approach could be improved by adopting a design strategy that addresses as well the serviceability limit states and associated evaluation criteria and gives methods for design and analysis as a function of the seismic zone and the importance of the structure. An earthquake with a return period of 1 in 50 years is proposed tentatively for the serviceability limit states with appropriate drift limits. The proposed serviceability limit states are shown to govern the design of buildings for values of the force modification factor greater, on average, than 3.Key words: analyses, earthquake, seismic design, serviceability limit state, steel, ultimate limit state.

Seismic Fragility Curves of an Arch Dam With Special Regard to Ultimate Limit State

2019 ◽  
Vol 5 (4) ◽  
Author(s):  
Christian Gasser ◽  
Markus Goldgruber ◽  
Christian Bucher
Keyword(s):  
Water Level ◽  
Seismic Analysis ◽  
Fragility Curves ◽  
Limit State ◽  
Arch Dam ◽  
Ultimate Limit State ◽  
Seismic Safety ◽  
Damage And Failure ◽  
Time Histories ◽  
Ultimate Limit

Abstract The seismic safety of an arch dam is analyzed by calculating fragility curves for different damage and failure mechanisms. The model includes fluid–structure–foundation interaction and considers contact and material type nonlinearities. The ultimate limit state (failure) is studied by means of a plastic-damage concrete model, especially developed for cyclic loadings. The time histories of the ground motions are generated randomly by means of Kanai–Tajimi filter. Moreover, ten parameters of the model are considered as random variables, including the water level. To the best knowledge of the authors, for the first time, water-level variability is accounted for in a probabilistic seismic analysis of a dam. It is studied if it is admissible to increase the efficiency of the Monte Carlo simulation (MCS) by assuming lognormal distributions for the fragility curves. In general, the aim of this work is to show the possibilities and difficulties of probabilistic seismic analysis tools when applied to a sophisticated mechanical model of a real structure.

scholarly journals Improvement of the Performance-Based Seismic Design Method of Cable Supported Bridges with the Resilient-Friction Base Isolation Systems

2020 ◽  
Vol 10 (11) ◽  
pp. 3942 ◽  
Author(s):  
Heungbae Gil ◽  
Kyoungbong Han ◽  
Junho Gong ◽  
Dooyong Cho
Keyword(s):  
Seismic Design ◽  
Design Method ◽  
Response Spectrum ◽  
Design Procedure ◽  
Time History ◽  
Modal Shape ◽  
Ground Acceleration ◽  
Performance Based Seismic Design ◽  
Seismic Design Method ◽  
Shape Analyses

In areas of civil engineering, the resilient friction base isolator (R-FBI) system has been used due to its enhanced isolation performance under seismic excitations. However, because nonlinear behavior of the R-FBI should be reflected in seismic design, effective stiffness (Keff) of the R-FBI is uniformly applied at both peak ground acceleration (PGA) of 0.08 g and 0.154 g which use a multimodal response spectrum (RS) method analysis. For rational seismic design of bridges, it should be required to evaluate the dynamics of the R-FBI from in-field tests and to improve the seismic design procedure based on the performance level of the bridges. The objective of this study is to evaluate the dynamics of the R-FBI and to suggest the performance-based seismic design method for cable-supported bridges with the R-FBI. From the comparison between the experiments’ results and modal shape analyses, the modal shape analyses using primary (Ku) or infinite stiffness (fixed end) showed a great agreement with the experimental results compared to the application of Keff in the shape analysis. Additionally, the RS or nonlinear time history method analyses by the PGA levels should be applied by reflecting the dynamic characteristics of the R-FBI for the reasonable and efficient seismic design.

DESIGN OF BOLTED CONNECTIONS SUBJECT TO TORSION AND SHEAR IN THE ULTIMATE LIMIT STRESS STATE

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Mohamed S. Abu-Yosef ◽  
Ezzeldin Y. Sayed-Ahmed ◽  
Emam A. Soliman
Keyword(s):  
Failure Modes ◽  
Focal Point ◽  
Design Method ◽  
Limit State ◽  
Bending Moment ◽  
Steel Structures ◽  
Ultimate Limit State ◽  
Shear Forces ◽  
Limit States ◽  
Ultimate Limit

Steel connections transferring axial and shear forces in addition to bending moment and/or torsional moment are widely used in steel structures. Thus, design of such eccentric connections has become the focal point of any researches. Nonetheless, behavior of eccentric connections subjected to shear forces and torsion in the ultimate limit state is still ambiguous. Most design codes of practice still conservatively use the common elastic analysis for design of the said connections even in the ultimate limit states. Yet, there are some exceptions such as the design method proposed by CAN/CSA-S16-14 which gives tabulated design aid for the ultimate limit state design of these connections based on an empirical equation that is derived for ¾ inch diameter A325 bearing type bolts and A36 steel plates. It was argued that results can also be used with a margin of error for other grade bolts of different sizes and steel of other grades. As such, in this paper, the performance of bolted connection subject to shear and torsion is experimentally investigated. The behavior, failure modes and factors affecting both are scrutinized. Twelve connections subject to shear and torsion with different bolts configurations and diameters are experimentally tested to failure. The accuracy of the currently available design equations proposed is compared to the outcomes of these tests.

A new seismic design method of simply supported girder bridges for very rare ground motions in the transverse direction

2020 ◽  
pp. 002072092094059
Author(s):  
Tianbo Peng ◽  
Haoyu Zou ◽  
Lizhi Wang
Keyword(s):  
Seismic Hazard ◽  
Seismic Design ◽  
Seismic Isolation ◽  
Transverse Direction ◽  
Design Method ◽  
Safety Evaluation ◽  
Seismic Safety ◽  
Simply Supported ◽  
Girder Bridges ◽  
Seismic Design Method

In most seismic design codes, usually two seismic hazard levels are taken into account, for example, Design Earthquake and Maximum Considered Earthquake. Several disastrous earthquakes have proved that seismic safety evaluation may underestimate seismic risks, which would result in serious damage of bridge structures. Therefore, a new higher level of seismic hazard named Very Rare Ground Motion (VRGM for short) is proposed innovatively to be considered in this paper for very important bridges. A novel seismic design method of simply supported girder bridges in the transverse direction for VRGMs is proposed at first. In the proposed method, seismic isolation bearings, tension-only braces and ductile piers are combined to improve the seismic performance and meet seismic requirements of VRGMs. Taking a simply supported girder bridge as a numerical analysis example, the proposed method is compared with two bridge seismic design methods adopted in current seismic codes and its parametric analysis is conducted. It’s shown that the proposed seismic design method can combine the ductility capacities of piers and the functions of seismic isolation bearings and reduce all the concerned structural seismic responses in VRGMs effectively. This work provides an educational demonstration for engineers dealing with similar problems.

Experimental Study on Direct Displacement-Based Seismic Design of RC Columns

2005 ◽  
Vol 21 (2) ◽  
pp. 117-124 ◽  
Author(s):  
Y.-Y. Lin ◽  
K.-C. Chang ◽  
Y.-L. Wang
Keyword(s):  
Seismic Design ◽  
Design Method ◽  
Experimental Studies ◽  
Design Procedure ◽  
Maximum Displacement ◽  
Rc Columns ◽  
Seismic Engineering ◽  
Displacement Based ◽  
Seismic Design Method ◽  
Displacement Based Seismic Design

AbstractFor performance-based seismic engineering of buildings, the direct displacement-based seismic design method is different from the coefficient method used in FEMA-273 and the capacity spectrum method adopted in ATC-40. The method not only is a linear static procedure but also is applied to the design of new constructions. This paper concerns with experimental studies on the accuracy of the direct displacement-based design procedure. Experimental results of three reinforced concrete (RC) columns designed by the displacement procedure are presented and discussed through pseudo-dynamic tests and cyclic loading tests. From the tests, it is shown that the stiffness degrading factor of RC columns plays a key role. The direct displacement-based seismic design method can reliably capture the maximum displacement demand of the test RC columns if the stiffness degrading factor adopted in the displacement design method for RC material is adequate.

scholarly journals A review of code provisions for torsional seismic effects in buildings

1997 ◽  
Vol 30 (3) ◽  
pp. 252-263 ◽  
Author(s):  
T. Paulay
Keyword(s):  
Seismic Design ◽  
Limit State ◽  
Ultimate Limit State ◽  
Deformation Pattern ◽  
Displacement Ductility ◽  
Torsional Response ◽  
Yield Displacement ◽  
Design Requirements ◽  
Ductility Capacity ◽  
Ultimate Limit

A series of recent studies of the seismic torsional response of ductile buildings is condensed and extended to serve as a basis for recommendations for possible amendments of the relevant clauses of the current New Zealand loadings standard [1]. It is postulated that the primary seismic design aim, associated with criteria of the ultimate limit state, should address displacement ductility demands and supply, as affected by twisting of the system, rather than torsional strength. Some well-established parameters, such as yield displacement, element and system stiffness, are redefined to enable the inelastic deformation pattern of rigid diaphragms to be simply quantified. The presentation concludes with specific recommendations and corresponding commentaries in a form suitable, with editorial modifications, for possible adoption as codified design requirements. To illustrate both the relevance of the recommendations and their simplicity, two numerical examples, showing the evaluation of the displacement ductility capacity of a model structure, are appended.

Direct Displacement Based Seismic Design of High Rise Structures with Strengthened Stories (II) - Application

2011 ◽  
Vol 250-253 ◽  
pp. 2186-2195
Author(s):  
Ke Jia Yang ◽  
Lin Zhu Sun ◽  
Lian Meng Chen
Keyword(s):  
Seismic Design ◽  
Mechanical Characteristics ◽  
Design Method ◽  
Design Procedure ◽  
High Rise ◽  
New Ideas ◽  
Earthquake Action ◽  
Displacement Based ◽  
Seismic Design Method ◽  
Displacement Based Seismic Design

Based on mechanical characteristics of high rise structures with strengthened stories, the author performed direct displacement based seismic design on a high rise structure with 2 strengthened stories according to the direct displacement based seismic design principle. The performance levels are set to be “serviceability” under medium earthquake and “life safety” under major earthquake, respectively. The design procedures are with the following features: (1) Definition and selection of “key” stories are based on mechanical characteristics of high rise structures with strengthened stories; (2) Determination of mode number and calculation of horizontal earthquake action verified the availability of the design procedure; (3) some new ideas are proposed to improve the earthquake action calculation and structural performance control. The design procedure verified the effectiveness, feasibility and availability of the proposed direct displacement based seismic design method.

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