Optimal Placement of Viscous Dampers in the Water Pipeline Networks Subjected to Near-Fault Earthquakes Using Genetic Algorithm

2013 ◽  
Author(s):  
Seyed Kazem Sadat Shokouhi ◽  
Azam Dolatshah ◽  
Hamid Reza Vosoughifar ◽  
Yousef Rahnavard
Keyword(s):  
Genetic Algorithm ◽  
Critical Points ◽  
Seismic Waves ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Optimal Placement ◽  
Viscous Dampers ◽  
Pipeline Network ◽  
Near Fault ◽  
Water Pipeline

Experiences of previous earthquakes demonstrate that lifelines have no proper performance exposed to Near-Fault (NF) earthquakes. Due to considerable effects of NF earthquakes and recommendation of the related design codes such as FEMA, evaluating the effects of these earthquakes on the pipelines is so important. In this research, the optimal placement of the viscous dampers in the water pipeline network subjected to NF earthquakes has been studied using Genetic Algorithm (GA). For this purpose, the water pipeline network of a zone in Tehran city was selected as a case study and was modeled using the Finite Element Method (FEM). Then, the 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 applied seismic waves. However, due to economical and technical issues, the optimal damper placement at critical points is necessary; all of the mentioned points were considered for optimization procedure using GA. Then, the viscous dampers were installed in the acquired optimal points. Eventually, a statistical test demonstrated optimum performance of the water pipelines network equipped with viscous dampers under NF earthquakes.

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.

Strengthening Research in the Longitudinal Frames of Prefabricated Structures with Viscous Dampers

2013 ◽  
Vol 671-674 ◽  
pp. 782-785
Author(s):  
Bin He ◽  
Jin Lai Pang ◽  
Cheng Qing Liu
Keyword(s):  
Seismic Performance ◽  
Pushover Analysis ◽  
Vertical Direction ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Viscous Dampers ◽  
Existing Building ◽  
Concrete Frame ◽  
Uniform Drift ◽  
Nonlinear Time History

For the lack of research in the longitudinal frame of prefabricated structure for its weak lateral stiffness, pushover analysis is conducted to evaluate the seismic performance of a fabricated concrete frame. Based on case study, the strengthening strategies with viscous dampers are analyzed. In view of the undesirable drift distribution and failure mode in the existing building, it is believed that arrangement of dampers should be designed to attain a uniform drift distribution. Based on the nonlinear time history analysis method, the strategy of damper allocation in vertical direction of the structure is investigated .Results indicate that a proper design might be attained based on the property of existing system, leading to a uniform drift distribution and better seismic performance.

scholarly journals Seismic Design of Bridges against Near-Fault Ground Motions Using Combined Seismic Isolation and Restraining Systems of LRBs and CDRs

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Xiaoli Li ◽  
Yan Shi
Keyword(s):  
Control System ◽  
Seismic Design ◽  
High Intensity ◽  
Seismic Isolation ◽  
Ground Motions ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Near Fault ◽  
Combined Control ◽  
Quantitative Design

This paper focuses on the seismic isolation design of near-fault bridges under the seismic excitations of near-fault ground motions in high-intensity earthquake zones and proposes a combined control system using lead rubber bearings (LRBs) and cable displacement restrainers (CDRs) along with ductility seismic resistance for the reinforced concrete piers. As part of the performance-based seismic design framework, this study provides the quantitative design criteria for multilevel performance-based objectives of a combined control system under conditions of frequent earthquake (E1), design earthquake (medium earthquake), and rare earthquake (E2). Moreover, in this study, a preliminary performance-based seismic isolation design for a near-fault actual highway bridge in high-intensity earthquake zones (basic peak of ground acceleration 0.4 g) was developed. Using nonlinear time-history analysis of the actual bridge under near-fault ground motions, the feasibility of a performance-based design method was validated. Furthermore, to ensure the predicted performance of the isolated bridges during a strong earthquake, a relatively quantitative design in structural details derived from the stirrup ratio of piers, expansion joints gap, supported length of capping beams, and limited vertical displacement response was obtained.

scholarly journals Seismic Response of the Three-Span Bridge with Innovative Materials Including Fault-Rupture Effect

2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
Jiping Ge ◽  
M. Saiid Saiidi
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Plastic Hinge ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Ground Displacement ◽  
Finite Element Software ◽  
Near Fault ◽  
Residual Displacements ◽  
Parallel Direction

The seismic performance of the SR99 Bridge with conventional and advanced details in Seattle, Washington, was studied via a nonlinear, time history analysis of a multidegree of freedom model. The bridge consists of three spans supported on two single-column piers and will be the first built bridge in the world in which superelastic shape memory alloy (SMA) and engineered cementitious composite (ECC) are implemented to reduce damage at plastic hinges and minimize residual displacements. Existing finite-element formulations in the finite-element software OpenSees are used to capture the response of the advanced materials used in the bridge. The earthquake induced by strike-slip fault was assumed to produce a surface rupture across the SR99 Bridge. The effect of the rupture was modeled by a static, differential ground displacement in the fault-parallel direction across the rupture. The synthetic suite of scaled bidirectional near-fault ground motions used in the analysis contains common near-fault features including a directivity pulse in the fault-normal direction and a fling step in the fault-parallel direction. Comparisons are made on behavior of two different bridge types. The first is a conventional reinforced concrete bridge and the second is a bridge with Nickel-Titanium (NiTi) SMA reinforcing bar at the plastic hinge zone and ECC in the whole column. Fault-parallel near-fault earthquakes typically exhibit a static permanent ground displacement caused by the relative movement of the two sides of the fault. When the fault is located between piers, the pier shows a higher demand. Fault-normal analysis results show effectiveness of the innovative interventions on the bridges in providing excellent recentering capabilities with minimal damage to the columns. But the maximum drift computed in the SMA bridge is slightly higher than reinforced concrete (RC) bridges, contributed by comparatively low stiffness of the superelastic SMA bars compared to the steel reinforcing bars.

scholarly journals Seismic Behavior of a Bridge with New Composite Tall Piers under Near-Fault Ground Motion Conditions

2020 ◽  
Vol 10 (20) ◽  
pp. 7377
Author(s):  
Zhehan Cai ◽  
Zhijian Wang ◽  
Kaiqi Lin ◽  
Ying Sun ◽  
Weidong Zhuo
Keyword(s):  
Design Method ◽  
Ground Motions ◽  
Time History ◽  
Steel Plates ◽  
Nonlinear Time History Analysis ◽  
Steel Beams ◽  
Box Section ◽  
Near Fault ◽  
Rigid Frame ◽  
Cfst Columns

Currently, the seismic designs of reinforced concrete (RC) bridges with tall piers are often accomplished following the ductility-based seismic design method. Though the collapses of the RC bridges with tall piers can be avoided, they are likely to experience major damage and loss of functionality when subjected to strong near-fault ground motions. The objectives of this study are to put forward an innovative design concept of a tall-pier system and its application in tall-pier bridges. The concept of the innovative tall-pier system is derived from the principle of earthquake-resilient structures, and is to improve the seismic performances of the tall-pier bridges under strong near-fault ground motions. The proposed tall-pier system has a box section and is composed of four concrete-filled steel tubular (CFST) columns and energy dissipating mild steel plates (EDMSPs). Trial design of a bridge with the new composite tall-pier system is performed based on a typical continuous rigid frame highway bridge with conventional RC box section tall piers. Both static analysis and nonlinear time history analysis of both the bridges with the new composite tall piers and conventional RC tall piers under the near-fault velocity pulse-type ground motions were conducted in Midas Civil2019 and ABAQUS. The results show that: under the design-based earthquake (DBE), the CFST columns and connecting steel beams remain elastic in the bridge with the new composite tall piers, while the damage is found in the replaceable EDMSPs which help dissipate the seismic input energy. The displacement responses of the new bridge are significantly smaller than those of the conventional bridge under DBE. It is concluded that the bridge with the new composite tall piers is seismic resilient under near-fault ground motions.

Experimental and Simulation Study of a Hybrid Frame Structure with Viscous Dampers

2012 ◽  
Vol 446-449 ◽  
pp. 894-899
Author(s):  
Hong Mei Zhang ◽  
Xi Lin Lu ◽  
Chun Guang Meng
Keyword(s):  
Shaking Table Test ◽  
Time History ◽  
Shaking Table ◽  
Frame Structure ◽  
Nonlinear Time History Analysis ◽  
Seismic Action ◽  
Test Model ◽  
Viscous Dampers ◽  
Scaled Model ◽  
Nonlinear Simulation

A Concrete-filled Rectangular Steel Tube (CRST) frame structure is studied in this paper by shaking table model test and nonlinear simulation. A number of viscous dampers are employed to insure the function of the building especially under seismic action for some of the main vertical elements of the building are not continuous. A shaking table test of a scaled model was conducted under different earthquake waves to investigate the structural behavior. And the nonlinear time-history analysis for the shaking table test model was also carried out by finite element analysis program according to the shaking table test. The simulation model was constructed in accordance with the tested specimen and the simulation effect was then validated by the tested results. To sum up, (1) there are no obvious weak stories on the damping equipped structure; (2) the dampers can reduce the displacement of the irregular to a certain degree.

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.

scholarly journals Effect of a Near Fault on the Seismic Response of a Base-Isolated Structure with a Soft Storey

2017 ◽  
Vol 25 (4) ◽  
pp. 34-46
Author(s):  
B. Athamnia ◽  
A. Ounis ◽  
M. Abdeddaim
Keyword(s):  
Seismic Isolation ◽  
Seismic Analysis ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Base Shear ◽  
Rc Structures ◽  
Soft Storey ◽  
Near Fault ◽  
Nonlinear Time History ◽  
Far Fault

AbstractThis study focuses on the soft-storey behavior of RC structures with lead core rubber bearing (LRB) isolation systems under near and far-fault motions. Under near-fault ground motions, seismic isolation devices might perform poorly because of large isolator displacements caused by large velocity and displacement pulses associated with such strong motions. In this study, four different structural models have been designed to study the effect of soft-storey behavior under near-fault and far-fault motions. The seismic analysis for isolated reinforced concrete buildings is carried out using a nonlinear time history analysis method. Inter-story drifts, absolute acceleration, displacement, base shear forces, hysteretic loops and the distribution of plastic hinges are examined as a result of the analysis. These results show that the performance of a base isolated RC structure is more affected by increasing the height of a story under nearfault motion than under far-fault motion.

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.

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.

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