EVALUATION OF CAPACITY SPECTRUM METHOD IN ESTIMATING SEISMIC DEMANDS OF TRIPLE PENDULUM BEARINGS UNDER NEAR-FIELD GROUND MOTIONS

2014 ◽  
Vol 14 (02) ◽  
pp. 1350062 ◽  
Author(s):  
GHOLAMREZA GHODRATI AMIRI ◽  
PEJMAN NAMIRANIAN
Keyword(s):  
Ground Motions ◽  
Near Field ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Base Shear ◽  
Capacity Spectrum Method ◽  
Seismic Demands ◽  
Spectrum Method ◽  
Capacity Spectrum ◽  
Triple Pendulum

Simplified methods for analyzing seismically isolated structures are always used either as a design procedure or as checking criteria for the results of time history procedure. The main purpose of this study is to evaluate the accuracy of one of these methods, the capacity spectrum method (CSM), in predicting the seismic demands, such as isolator displacement and maximum base shear force, of structures with triple pendulum bearings (TPBs) under bidirectional near-field ground motions. By comparing the results of this method with those of the nonlinear time history analysis (NTHA), it can be concluded that the CSM is able to predict the maximum isolator displacement and base shear of the structure with acceptable accuracy. It should be noted that for softer soil site conditions, the values of demand calculated by CSM are sometimes underestimated compared with the results of NTHA, especially when the effective period of system exceeds 3.0 s or when the TPB works on the fifth regime of its pendulum mechanism.

scholarly journals Isolating system using U Shaped steel damper

2021 ◽  
Vol 309 ◽  
pp. 01136
Author(s):  
Siripuram Vamshisheela ◽  
Atulkumar Manchalwar
Keyword(s):  
Base Isolation ◽  
Ground Motions ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Base Shear ◽  
Energy Device ◽  
History Analysis ◽  
Structural Responses ◽  
Nonlinear Time History ◽  
Story Building

In this work the performance of U-Shaped Steel Isolator is evaluated for a 5-story building subjected to seismic and blast vibrations. The structure is analysed using SAP 2000 software and a nonlinear time history analysis is carried out. The effectiveness of using base isolation is studied by comparing the structural responses of the building with isolator and without isolator and noticeable difference was observed. As the U-Shaped isolator absorbs the energy in all directions, it effectively controls the structural responses. In this study, the building is subjected to four different seismic and four different blast induced ground motions. It was observed that by the use of supplementary energy device there is reduction in top story acceleration, base shear and less deformation in the structure. This study concludes that the use of isolator has been effective in minimizing structural responses.

scholarly journals Seismic Performance Evaluation of Steel Buildings with Oil Dampers Using Capacity Spectrum Method

2021 ◽  
Vol 11 (6) ◽  
pp. 2687
Author(s):  
Ahmad Naqi ◽  
Taiki Saito
Keyword(s):  
Seismic Performance ◽  
Response Spectrum ◽  
Damping Ratio ◽  
Time History ◽  
Linearization Method ◽  
Equivalent Linearization ◽  
Steel Buildings ◽  
Capacity Spectrum Method ◽  
Spectrum Method ◽  
Capacity Spectrum

This study proposes a capacity spectrum Method (CSM)-based procedure to estimate the maximum seismic performance of steel buildings passively controlled with bilinear oil dampers. In the proposed CSM, the maximum seismic response of a building was estimated, in the acceleration-displacement response spectrum, as the intersection between the capacity curve and the damping-adjusted demand curves, using the equivalent linearization method. The building equivalent damping ratio was determined by the sum of the inherent damping, and the square root of sum of squares (SRSS) of the hysteretic damping and the viscous damping of the supplemental oil devices. The calculation steps of the proposed CSM are explained in detail based on the equivalent single degree of freedom (ESDOF) system, and its accuracy was examined by comparison with time history analysis (THA) results. Two model steel buildings of 4 and 10 stories, uniformly equipped with oil dampers along the height, were subjected to six selected earthquake ground motions scaled to be compatible with Level-2 earthquakes, as defined in the Japanese Building Standard Law. The seismic performance of the buildings was estimated by the proposed CSM procedure and compared with the results of nonlinear THA in terms of the maximum story displacements and the shear forces. It was observed that the proposed CSM scheme provided a satisfactory accuracy to assess the maximum nonlinear response of steel buildings passively controlled with oil dampers.

scholarly journals Response control of structures under Seismic and Blast induced ground motions

2021 ◽  
Vol 309 ◽  
pp. 01137
Author(s):  
Vamshisheela Siripuram ◽  
Atulkumar Manchalwar
Keyword(s):  
Base Isolation ◽  
Ground Motions ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Base Shear ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Fixed Base ◽  
Isolation Device ◽  
Nonlinear Time History

In the present paper an investigation is carried out to evaluate the efficiency of Base Isolation device in a building subjected to both seismic and blast induced ground motions. A 5-story building is modelled with different story stiffness and floor masses is considered in this study. In SAP 2000 software two buildings, one with fixed base and the other with isolated base are designed and nonlinear time history analysis is conducted. The structural responses of these two models subjected to four recorded earthquakes and four different blast ground accelerations is compared in this study. The base isolated device such as lead/rubber bearing have proved to be effective in reducing the base Shear and Top story acceleration, and also increase in Hysteresis energy in the base isolated structure subjected to seismic and blast vibrations.

Sensitivity analysis of the influence of ground motion intensity levels on the seismic behavior of steel frames in assessment of the target displacement considering near-fault effects

2020 ◽  
Vol 47 (4) ◽  
pp. 470-486
Author(s):  
Alireza Esfahanian ◽  
Ali Akbar Aghakouchak
Keyword(s):  
Ground Motions ◽  
Steel Frames ◽  
Time History ◽  
Time History Analysis ◽  
Nonlinear Time History Analysis ◽  
Seismic Demands ◽  
Near Fault ◽  
History Analysis ◽  
Nonlinear Time History ◽  
Far Fault

Nonlinear time-history analysis conducted as part of a performance-based seismic design approach often require that the ground motion records are selected and then scaled to a specified level of seismic intensity. In such analyses, besides an adequate structural model, a set of acceleration time-series is needed as the most realistic representation of the seismic action. In this paper, the effects of scaling procedure on seismic demands of steel frames are investigated. To this, two special steel moment-resisting frames with considerable higher mode effects, and two sets of ground motions, including near-fault and far-fault motions are considered. Moreover, three scaling procedures are introduced for performing nonlinear dynamic time-history analysis of structures. Among different demands, lateral roof displacement and interstory drift are selected as seismic demands. The height-wise distribution of demands shows that the inelastic seismic demands of the near-fault pulse-like ground motions differ considerably from those of far-fault ones. These results show that the story drifts are mostly larger for far-fault motions in the upper story levels in comparison to near-fault records and in the lower floors, the reverse is true. Thus, the scaling procedures directly affect the results of seismic demands and choosing different methods would result in varying responses. Moreover, a low-cost and fairly effective procedure is proposed to estimate the target displacement demands of buildings from response-spectrum analyses, considering near-fault effects. The precision of this method is verified by nonlinear time-history analysis results, as the benchmark solution, and acceptable improvements have been achieved.

Two-Dimensional Capacity Spectrum Method and Seismic Damage Assessment for RC Structures

2011 ◽  
Vol 243-249 ◽  
pp. 79-88
Author(s):  
Hao Xiang He ◽  
Hong Nan Li
Keyword(s):  
Damage Assessment ◽  
Damage Index ◽  
Time History ◽  
Seismic Damage ◽  
Two Dimensional ◽  
Capacity Spectrum Method ◽  
Spectrum Method ◽  
Capacity Spectrum ◽  
Seismic Damage Assessment ◽  
Capacity Method

The force-deformation curve of a reinforced concrete structure in push-over analysis is used to compute the corresponding damage index. A simplified and practical method is established for seismic damage assessment in combination with capacity spectrum method. The two-dimensional capacity spectrum method and the combination of the damage in two directions are discussed. A numerical example using single and double horizontal capacity method and time history analysis demonstrate that the response and damage of structure can be computed accurately in the two-dimensional capacity method. The common trend of structural torsional response can also be reflected. The results show the two-dimensional capacity method is valid and simple.

Displacement Based Seismic Performance Evaluation of Reinforcement Concrete Structures

2010 ◽  
Vol 163-167 ◽  
pp. 1063-1067
Author(s):  
Qing Xuan Shi ◽  
Qiu Wei Wang ◽  
Kun Yang
Keyword(s):  
Performance Evaluation ◽  
Seismic Performance ◽  
Time History ◽  
Time History Analysis ◽  
Capacity Spectrum Method ◽  
Seismic Performance Evaluation ◽  
Spectrum Method ◽  
Capacity Spectrum ◽  
History Analysis ◽  
Displacement Based

To further understand displacement based seismic theory of building structures, the seismic performance evaluation using capacity spectrum method related to damping is carried out for the reinforced concrete frame-shear wall model structure of a thermal power main plant. By comparing with time-history analysis results, it can be seen that some problems such as equivalence of multi-degree-of-freedom system and value of equivalent damping ratio in capacity spectrum method remains to be further investigated. Force and displacement response of structures and plastic hinges position of all members could be obtained through nonlinear push-over analysis after determining the top displacement; weak parts and damage pattern of structures could also be easily found out by this method. At last, research shows that dynamic time-history analysis can be replaced by static push-over analysis, which is regarded as an exact seismic performance evaluation method by contrast.

scholarly journals Comparison of Novel Seismic Protection Devices to Attenuate the Earthquake Induced Energy

Actuators ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 73
Author(s):  
Osman Hansu ◽  
Esra Mete Güneyisi
Keyword(s):  
Lateral Displacement ◽  
Time History ◽  
Seismic Protection ◽  
Base Shear ◽  
Seismic Demands ◽  
Nonlinear Time History Analyses ◽  
History Of ◽  
Protection Devices ◽  
Nonlinear Time History ◽  
Better Than

This study addresses an alternative use of viscous dampers (VDs) associated with buckling restrained braces (BRBs) as innovative seismic protection devices. For this purpose, 4-, 8- and 12-story steel bare frames were designed with 6.5 m equal span length and 4 m story height. Thereafter, they were seismically improved by mounting the VDs and BRBs in three patterns, namely outer bays, inner bays, and all bays over the frame heights. The structures were modeled using SAP 2000 software and evaluated by the nonlinear time history analyses subjected to the six natural ground motions. The seismic responses of the structures were investigated for the lateral displacement, interstory drift, absolute acceleration, maximum base shear, and time history of roof displacement. The results clearly indicated that the VDs and BRBs reduced seismic demands significantly compared to the bare frame. Moreover, the all-bay pattern performed better than the others.

Seismic response analysis of steel–concrete hybrid wind turbine tower

2021 ◽  
pp. 107754632110075
Author(s):  
Junling Chen ◽  
Jinwei Li ◽  
Dawei Wang ◽  
Youquan Feng
Keyword(s):  
Wind Turbine ◽  
Response Spectrum ◽  
Ground Motions ◽  
Time History ◽  
Seismic Action ◽  
Response Spectrum Method ◽  
Spectrum Method ◽  
Wind Turbine Tower ◽  
Ground Types ◽  
Nonlinear Time History

The steel–concrete hybrid wind turbine tower is characterized by the concrete tubular segment at the lower part and the traditional steel tubular segment at the upper part. Because of the great change of mass and stiffness along the height of the tower at the connection of steel segment and concrete segment, its dynamic responses under seismic ground motions are significantly different from those of the traditional steel tubular wind turbine tower. Two detailed finite element models of a full steel tubular tower and a steel–concrete hybrid tower for 2.0 MW wind turbine built in the same wind farm are, respectively, developed by using the finite element software ABAQUS. The response spectrum method is applied to analyze the seismic action effects of these two towers under three different ground types. Three groups of ground motions corresponding to three ground types are used to analyze the dynamic response of the steel–concrete hybrid tower by the nonlinear time history method. The numerical results show that the seismic action effect by the response spectrum method is lower than those by the nonlinear time history method. And then it can be concluded that the response spectrum method is not suitable for calculating the seismic action effects of the steel–concrete hybrid tower directly and the time history analyses should be a necessary supplement for its seismic design. The first three modes have obvious contributions on the dynamic response of the steel–concrete hybrid tower.

scholarly journals DESING SPECTRUMS FOR THE CENTRAL NORTH OF QUI-TO AND SEISMIC ANALYSIS OF STEEL STRUCTURES USING THE CAPACITY SPECTRUM METHOD.

2014 ◽  
Vol 12 (3) ◽  
Author(s):  
Roberto Rodrigo Aguiar
Keyword(s):  
High School ◽  
Steel Structures ◽  
Capacity Spectrum Method ◽  
North Central ◽  
Seismic Microzoning ◽  
Spectrum Method ◽  
Performance Point ◽  
Capacity Spectrum ◽  
Elastic Response Spectra ◽  
The City

The city of Quito lies on geological faults that have no surface outcrop but are moving with a speed of 2-4 mm per year. The last strong earthquake associated with these thrust faults, was rec-orded in 1587 and had a magnitude of 6.4; so it has been more than 400 years, there is a large amount of stored energy, and the probability of an earthquake occurring is very high. Therefore, this article presents, firstly, the periods of recurrence of these faults; then a microzoning of the north central part of the city and the elastic response spectra for 5% damped associated to the Llumbisi- La Bota segment fault, ILB. And subsequently, an analysis of nine steel structures from one to nine storeys assuming that they are situated in the following three areas of north central Quito: the old Quito Tenis; La Gasca and Benalcazar High School. Using the Capacity Spectrum Method MEC, the seismic response is found with the presence of three spectrums as prescribed in the Ecuadorian Construction Regula-tions NEC-11; the recommendation in the study of the seismic microzoning of Quito ERN-12 and those found in the seismic microzoning associated with the fault ILB. Three types of responses are indicated for each location, the structures situated in the old Quito Tenis present a performance point found using the Capacity Spectrum Method MEC; for those in La Gasca, a maximum lateral displacement is indicated in each storey; and the structures situated in the Benalcazar High School present maximum interstorey drifts. It should be highlighted that the lateral displacements and interstorey drifts are reaching the end of their performance, thus the conclusions to be found in this study about which spectrum the maximum response has could be inferred from any of the three structural parameters.

A mathematical basis for the convergence of the capacity spectrum method

2004 ◽  
Vol 33 (9) ◽  
pp. 1059-1066 ◽  
Author(s):  
Yu-Yuan Lin ◽  
Tsai-Fu Chuang ◽  
Kuo-Chung Chang
Keyword(s):  
Capacity Spectrum Method ◽  
Mathematical Basis ◽  
Spectrum Method ◽  
Capacity Spectrum
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