scholarly journals Seismic Performance of Steel Structure-Foundation Systems Designed According to Eurocode 8 Provisions: The Case of Near-Fault Seismic Motions

Buildings ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 63 ◽  
Author(s):  
Panagiota Katsimpini ◽  
Foteini Konstandakopoulou ◽  
George Papagiannopoulos ◽  
Nikos Pnevmatikos ◽  
George Hatzigeorgiou
Keyword(s):  
Seismic Performance ◽  
Time History ◽  
Steel Structure ◽  
Steel Structures ◽  
Eurocode 8 ◽  
Near Fault ◽  
Building Foundation ◽  
Steel Building ◽  
Near Fault Earthquakes ◽  
Nonlinear Time History

The seismic performance of steel structure-foundation systems subjected to near-fault earthquakes was assessed on the basis of response results from nonlinear time-history seismic analyses. The structural results included the maximum values for residual interstory drift ratios, base shears, and overturning moments of the steel structures, as well as the maximum values for residual settlement and tilting of the foundations. In order to reveal the influence of soil-building-interaction on the aforementioned response results, the steel building-foundation systems were designed according to Eurocode 8 provisions, assuming initially fixed and then compliant base conditions. It was concluded that for the case of near-fault seismic motions, good seismic performance of steel building-foundation hybrid systems designed according to European Codes was not guaranteed. A particular thing to note for these systems under near-fault seismic motions was that the seismic performance of the steel structure was most likely unacceptable, while one of the foundations was always acceptable.

scholarly journals The Effect of Long Duration Earthquakes on the Overall Seismic Behavior of Steel Structures Designed According to Eurocode 8 Provisions

Vibration ◽  
2020 ◽  
Vol 3 (4) ◽  
pp. 464-477
Author(s):  
Panagiota Katsimpini ◽  
Foteini Konstandakopoulou ◽  
George A. Papagiannopoulos ◽  
Nikos Pnevmatikos ◽  
George D. Hatzigeorgiou
Keyword(s):  
Seismic Performance ◽  
Time History ◽  
Steel Structures ◽  
Eurocode 8 ◽  
Steel Buildings ◽  
Long Duration ◽  
Base Steel ◽  
Fixed Base ◽  
Permanent Settlement ◽  
Nonlinear Time History

Premature and simultaneous buckling of several steel braces in steel structures due to the prolonged duration of a seismic motion is one of the issues that must be addressed in the next version of Eurocode 8. In an effort to contribute towards the improvement of the seismic design provisions of Eurocode 8, an evaluation of the overall behavior of some steel building-foundation systems under the action of long duration seismic motions is performed herein by means of nonlinear time-history seismic analyses, taking into account soil–structure interaction (SSI) effects. In particular, the maximum seismic response results—in terms of permanent interstorey drifts, overturning moments and base shears of the steel buildings as well as of the permanent settlement and tilting of their foundations—are computed. It is found that the seismic performance of steel buildings when subjected to long duration seismic motions is: (i) acceptable for the two and five-storey fixed base steel buildings and for the two-storey steel buildings with SSI effects included; (ii) unacceptable for the eight-storey fixed base steel buildings and for the five and eight-storey steel buildings with SSI effects included. In all cases of steel buildings with SSI effects included, the seismic performance of the mat foundation, as expressed by the computed values of residual settlement and tilting, is always acceptable.

Evaluation of Seismic Behavior on Steel Frames with TSW Semi-Rigid Connections under the Nonlinear Time History Analysis

2012 ◽  
Vol 166-169 ◽  
pp. 2083-2087
Author(s):  
Miaad Najdian ◽  
Mohsen Izadinia
Keyword(s):  
Time History ◽  
High Energy ◽  
Time History Analysis ◽  
Nonlinear Time History Analysis ◽  
Near Fault ◽  
Good Ability ◽  
History Analysis ◽  
Ductile Behavior ◽  
Near Fault Earthquakes ◽  
Nonlinear Time History

Movements of pulse shape and the high energy applied in short duration by the near fault earthquake, causes brittle fracture in rigid connections that during the Northridge 1994 and Kobe 1995 earthquakes was frequently seen. Rigid connections, which are generally welded due to lack of ductility, have low energy absorption capability. On the other hand semi-rigid connections have a ductile behavior and have a good ability to absorb energy. The purpose of this paper is analysis and compares the behaviors of “rigid” and “TSW semi-rigid” connections under the near fault earthquakes with nonlinear time history analysis by perform 3D software.

Performance of Bridges Isolated with Sliding-Lead Rubber Bearings Subjected to Near-Fault Earthquakes

2020 ◽  
Vol 20 (02) ◽  
pp. 2050023 ◽  
Author(s):  
Wenzhi Zheng ◽  
Hao Wang ◽  
Hong Hao ◽  
Kaiming Bi ◽  
Huijun Shen
Keyword(s):  
Time History ◽  
Isolation System ◽  
Peak Displacement ◽  
Residual Displacement ◽  
Near Fault ◽  
Lead Rubber Bearing ◽  
Base Forces ◽  
Near Fault Earthquakes ◽  
Rubber Bearings ◽  
Nonlinear Time History

This paper investigates the seismic performance of bridges installed with a sliding-lead rubber bearing (LRB) isolation system subjected to near-fault earthquakes. A three-span continuous bridge isolated with sliding-LRB system is used as an example. Nonlinear time history analyses are conducted to investigate the sensitivity effects of isolation period, friction coefficient and sliding displacement limit on the bridge responses. The responses of the sliding-LRB system are compared with those of the conventional LRB system. The results show that the base forces of the piers can be reduced by employing proper friction coefficients. However, the residual displacement of the sliding-LRB system may be larger compared with that of the conventional LRB system. To overcome this disadvantage, an improved solution to reduce the residual displacement is proposed with its effectiveness investigated. It was also demonstrated that the residual displacement and peak displacement can be effectively reduced by employing the shape memory alloy devices in the sliding-LRB system without significantly increasing the base forces.

Seismic Behavior Evaluation of Semi-Rigid Steel Frames with EEP Connections under the near-Fault Earthquakes

2012 ◽  
Vol 174-177 ◽  
pp. 561-565
Author(s):  
Miaad Najdian ◽  
Mohsen Izadinia
Keyword(s):  
Time History ◽  
The Other ◽  
Nonlinear Time History Analysis ◽  
Near Fault ◽  
Good Ability ◽  
History Analysis ◽  
Ductile Behavior ◽  
Near Fault Earthquakes ◽  
Nonlinear Time History ◽  
3D Software

Pulse shape motions and huge amount of energy applied in short duration by the near fault earthquake, cause brittle fracture in welded connections, which is widely observed in Kobe 1995 and Northridge 1994 earthquakes. Rigid connections, which are generally welded due to lack of ductility, have low energy absorption capability. On the other hand, Semi-rigid connections have a ductile behavior and have a good ability to absorb energy. The purpose of this paper is analysis and compares the behaviors of “rigid” and “EEP semi-rigid” connections in cases of “four bolt extended”, “eight bolt extended stiffened” and “eight bolt, four bolts wide, extended stiffened” under the near fault earthquakes with nonlinear time history analysis by perform 3D software. The results shown that the steel frame with “four bolt extended” semi-rigid connections have appropriate performance compared to the other frames.

scholarly journals Effectiveness of modified pushover analysis procedure for the estimation of seismic demands of buildings subjected to near-fault ground motions having fling step

2013 ◽  
Vol 13 (6) ◽  
pp. 1579-1593 ◽  
Author(s):  
A. Mortezaei ◽  
H. R. Ronagh
Keyword(s):  
Ground Motions ◽  
Pushover Analysis ◽  
Time History ◽  
Building Structures ◽  
Seismic Demands ◽  
Near Fault ◽  
Load Pattern ◽  
Dynamic Time ◽  
Near Fault Earthquakes ◽  
Nonlinear Time History

Abstract. Near-fault ground motions with long-period pulses have been identified as being critical in the design of structures. These motions, which have caused severe damage in recent disastrous earthquakes, are characterized by a short-duration impulsive motion that transmits large amounts of energy into the structures at the beginning of the earthquake. In nearly all of the past near-fault earthquakes, significant higher mode contributions have been evident in building structures near the fault rupture, resulting in the migration of dynamic demands (i.e. drifts) from the lower to the upper stories. Due to this, the static nonlinear pushover analysis (which utilizes a load pattern proportional to the shape of the fundamental mode of vibration) may not produce accurate results when used in the analysis of structures subjected to near-fault ground motions. The objective of this paper is to improve the accuracy of the pushover method in these situations by introducing a new load pattern into the common pushover procedure. Several pushover analyses are performed for six existing reinforced concrete buildings that possess a variety of natural periods. Then, a comparison is made between the pushover analyses' results (with four new load patterns) and those of FEMA (Federal Emergency Management Agency)-356 with reference to nonlinear dynamic time-history analyses. The comparison shows that, generally, the proposed pushover method yields better results than all FEMA-356 pushover analysis procedures for all investigated response quantities and is a closer match to the nonlinear time-history responses. In general, the method is able to reproduce the essential response features providing a reasonable measure of the likely contribution of higher modes in all phases of the response.

scholarly journals Seismic Performance of Steel Frames with Inverted V-Braces for North Cyprus

2019 ◽  
Vol 9 (1) ◽  
pp. 4314-4320
Keyword(s):  
Seismic Performance ◽  
Time History ◽  
Steel Structure ◽  
Steel Structures ◽  
Lateral Force ◽  
Load Resistance ◽  
Lateral Load ◽  
Vital Role ◽  
Lateral Load Resistance ◽  
Bracing System

Cyprus Island is located in a high-risk zone, in which the buildings should have lateral load-resistance systems to resist the lateral imposed loads. Bracings play a vital role in the structural behavior of buildings during an earthquake. There are many bracing systems that can be found thorough searching in the literature. However, there are insufficient studies regarding the inverted-V bracing system in accordance with the Northern Cyprus seismic code of NCSC-2015. In this study, the seismic performance of steel structures equipped with various types of inverted-V bracing systems is investigated for mid-rise and high-rise buildings in accordance with NCSC-2015 code. Several steel structure buildings having different lateral load-resistance systems are analyzed under different loading patterns applying ETABS2016 software. For this purpose, linear static equivalent lateral force method (ELFM), nonlinear static (Pushover) and nonlinear dynamic time-history (TH) analyses were adopted. The obtained results in this research indicate that the inverted-V bracing systems dramatically enhance the performance of the steel structures more particularly when the earthquake is applied perpendicular to the weak axis of the columns. This indicates that the inverted-V bracing system is an effective solution to resist the applied lateral loads while maintaining the functionality of the building. By applying the regression analysis some practical equations were submitted for the stiffness factor to be employed in similar cases as a guideline

The Influence of Viscous Dampers on the Better Performance of Water Pipelines Subjected to Near-Fault Earthquakes

2013 ◽  
Author(s):  
Seyed Kazem Sadat Shokouhi ◽  
Azam Dolatshah ◽  
Hamid Reza Vosoughifar ◽  
Yousef Rahnavard
Keyword(s):  
Seismic Waves ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Viscous Dampers ◽  
Element Analysis ◽  
Near Fault ◽  
History Analysis ◽  
Water Pipelines ◽  
Near Fault Earthquakes ◽  
Nonlinear Time History

Experiences of the previous earthquakes such as Bam, Northridge etc demonstrate that lifelines have no proper performance due to Near-Fault (NF) earthquakes. Hence, this research evaluates the influence of viscous dampers on the better performance of the water pipelines subjected to NF earthquakes. For this purpose, the water pipelines network of a zone in Tehran city was selected as a case study. The pipeline network was modeled using Finite Element Analysis (FEA), and nonlinear time-history analysis was undertaken via seismic scaled records of NF earthquakes. The obtained results indicated the critical points of network which were failed due to seismic waves. As a solution, viscous dampers were employed for improving the behavior of the mentioned points. The obtained results demonstrate that the failure points were retrofitted efficiently by viscous dampers.

Dynamic Characteristics of Base-Isolated Steel Frame under Seismic Ground Motion

2011 ◽  
Vol 255-260 ◽  
pp. 2341-2344
Author(s):  
Mohammad Saeed Masoomi ◽  
Siti Aminah Osman ◽  
Ali Jahanshahi
Keyword(s):  
Ground Motion ◽  
Base Isolation ◽  
Time History ◽  
Steel Structure ◽  
Steel Structures ◽  
Steel Frame ◽  
Nonlinear Time History Analysis ◽  
Seismic Load ◽  
Vector Method ◽  
Seismic Ground Motion

This paper presents the performance of base-isolated steel structures under the seismic load. The main goals of this study are to evaluate the effectiveness of base isolation systems for steel structures against earthquake loads; to verify the modal analysis of steel frame compared with the hand calculation results; and development of a simulating method for base-isolated structure’s responses. Two models were considered in this study, one a steel structure with base-isolated and the other without base-isolated system. The nonlinear time-history analysis of both structures under El Centro 1940 seismic ground motion was used based on finite element method through SAP2000. The mentioned frames were analyzed by Eigenvalue method for linear analysis and Ritz-vector method for nonlinear analysis. Simulation results were presented as time-acceleration graphs for each story, period and frequency of both structures for the first three modes.

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