scholarly journals Enhancing Seismic Capacity of Pile-Supported Wharves Using Yielding Dampers

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Seyed Amin Mousavi ◽  
Khosrow Bargi
Keyword(s):  
Numerical Study ◽  
Retaining Wall ◽  
Nonlinear Behavior ◽  
Optimization Procedure ◽  
Seismic Capacity ◽  
Ground Acceleration ◽  
Design Guideline ◽  
Factors Affecting ◽  
Quay Wall ◽  
The Stability

This paper presents a numerical study on the seismic response of pile-supported wharves equipped with metallic yielding dampers. Using 20 ground acceleration records, the contribution of the yielding damper is examined, and its main parameters are optimized through a parametric study. In the current study, considering coupling effects of different parameters, a new optimization procedure is proposed. The obtained results indicate that the stability condition of the retaining wall (quay wall) behind the wharf, period of the soil-wharf system, and also maximum allowable ductility ratio of the damper are the key factors affecting the optimum damper parameters. A simplified design guideline is proposed for either the design or the retrofit purposes followed by a numerical assessment to evaluate the contribution of the proposed damper on the seismic behavior of a typical pile-supported wharf. The obtained results show that yielding dampers, through their nonlinear behavior, can dissipate a large portion of seismic input energy and mitigate piles damages which have been observed in earlier earthquake events.

scholarly journals Two-Stage Optimization Method for the Bearing Layout of Isolated Structure

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Yu Dang ◽  
GenXiong Zhao ◽  
HongTu Tian ◽  
Guobao Li
Keyword(s):  
Optimization Technique ◽  
Optimal Solution ◽  
Nonlinear Behavior ◽  
Optimization Procedure ◽  
Optimization Method ◽  
Design Parameters ◽  
Two Stage ◽  
Factors Affecting ◽  
Lead Rubber Bearing ◽  
The Cost

Design of seismic isolated building is often a highly iterative and tedious process due to the nonlinear behavior of the system, a large range of design parameters, and uncertainty of ground motions. It is needed to consider a comprehensive optimization procedure in the design of isolated buildings with optimized performances. This can be accomplished by applying a rigorous optimization technique. However, due to many factors affecting the performance of isolated buildings, possible solutions are abundant, and the optimal solution is difficult to obtain. In order to simplify the optimization process, an isolated building is always modeled as a shear-type structure supported on the isolated layer, and the optimal results are the parameters of the isolated layer which could not be used as a practical design of the isolated structure. A two-stage optimization method for designing isolated buildings as a practical and efficient guide is developed. In the first stage, a 3D isolated building model is adopted that takes into account of nonlinear behavior in building and isolation devices. The isolation devices are simplified as a kind of lead-rubber bearing. The genetic algorithm is used to find the optimal parameters of the isolated layer. In the second stage, the location parameters of isolation bearing layout are optimized. Moreover, the cost of the isolation bearing layout should be as low as possible. An integer programming method is adopted to optimize the number of each type of isolator. Considering vertical bearing capacity of isolators and the minimum eccentricity ratio of the isolated layer, the optimal bearing layout of the isolated building can be obtained. The proposed method is demonstrated in a typical isolated building in China. The optimum bearing layout of the isolated building effectively suppresses the structural seismic responses, but the cost of the isolated layer might slightly increase.

scholarly journals A Numerical Study of the Effect of Particle Size on Particle Deposition on Turbine Vanes and Blades

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110178
Author(s):  
Zhengang Liu ◽  
Weinan Diao ◽  
Zhenxia Liu ◽  
Fei Zhang
Keyword(s):  
Particle Size ◽  
Particle Deposition ◽  
Numerical Study ◽  
Stokes Number ◽  
Capture Efficiency ◽  
Particle Capture ◽  
Factors Affecting ◽  
Pressure Surface ◽  
Deposition Area ◽  
Turbine Vanes

Particle deposition could decrease the aerodynamic performance and cooling efficiency of turbine vanes and blades. The particle motion in the flow and its temperature are two important factors affecting its deposition. The size of the particle influences both its motion and temperature. In this study, the motion of particles with the sizes from 1 to 20 μm in the first stage of a turbine are firstly numerically simulated with the steady method, then the particle deposition on the vanes and blades are numerically simulated with the unsteady method based on the critical viscosity model. It is discovered that the particle deposition on vanes mainly formed near the leading and trailing edge on the pressure surface, and the deposition area expands slowly to the whole pressure surface with the particle size increasing. For the particle deposition on blades, the deposition area moves from the entire pressure surface toward the tip with the particle size increasing due to the effect of rotation. For vanes, the particle capture efficiency increases with the particle size increasing since Stokes number and temperature of the particle both increase with its size. For blades, the particle capture efficiency increases firstly and then decreases with the particle size increasing.

A numerical study on the nonlinear behavior of corner supported flat and curved panels

2017 ◽  
Vol 88 (4) ◽  
pp. 503-516 ◽  
Author(s):  
Gaurav Watts ◽  
M. K. Singha ◽  
S. Pradyumna
Keyword(s):  
Numerical Study ◽  
Nonlinear Behavior ◽  
Curved Panels

DISLOCATION OF FACE-SLABS OF ZIPINGPU CONCRETE FACE ROCKFILL DAM DURING WENCHUAN EARTHQUAKE

2012 ◽  
Vol 06 (02) ◽  
pp. 1250007 ◽  
Author(s):  
DEGAO ZOU ◽  
YANG ZHOU ◽  
HOE I. LING ◽  
XIANJING KONG ◽  
BIN XU
Keyword(s):  
Wenchuan Earthquake ◽  
Limit Equilibrium ◽  
Failure Surface ◽  
Ground Acceleration ◽  
Factors Affecting ◽  
2008 Wenchuan Earthquake ◽  
Rockfill Dam ◽  
Concrete Face ◽  
Concrete Face Rockfill Dam ◽  
Water Elevation

Zipingpu concrete face rockfill dam (CFRD) is one of the tallest dams that have ever been subjected to strong earthquake shaking and recorded damages. In this paper, finite element method and limit equilibrium method are used to determine the most critical failure surface for Zipingpu CFRD during the 2008 Wenchuan earthquake in China. The dislocation damage of the face-slab joint was then obtained from the sliding block analysis. The major factors affecting dislocation displacement of face-slabs were analyzed. The results showed that the rigid sliding block method is relevant for analyzing the damage of face-slabs of CFRD during earthquake. The peak ground acceleration had a significant influence on the dislocation. As the acceleration of the dam increases with the height while the strength of face-slab joints reduces, the dislocation could easily occur when the upstream slope of the dam started to slide. The water elevation had considerable impact on the dislocation of face-slabs during strong shaking. There might be no dislocation of face-slabs at full reservoir, and the water elevation just above construction joints would induce larger damage.

scholarly journals Optimization Of Multi-Module CrN/CrCN Coatings

2015 ◽  
Vol 60 (2) ◽  
pp. 1037-1043
Author(s):  
Ł. Szparaga ◽  
P. Bartosik ◽  
A. Gilewicz ◽  
J. Ratajski
Keyword(s):  
Optimization Procedure ◽  
Stress And Strain ◽  
Pareto Optimal ◽  
Mutual Distance ◽  
Pareto Optimal Solutions ◽  
Optimal Solutions ◽  
Decision Criteria ◽  
Decision Variables ◽  
42Crmo4 Steel ◽  
The Stability

Abstract In the paper was proposed optimization procedure supporting the prototyping of the geometry of multi-module CrN/CrCN coatings, deposited on substrates from 42CrMo4 steel, in respect of mechanical properties. Adopted decision criteria were the functions of the state of internal stress and strain in the coating and substrate, caused by external mechanical loads. Using developed optimization procedure the set of optimal solutions (Pareto-optimal solutions) of coatings geometry parameters, due to the adopted decision criteria was obtained. For the purposes of analysis of obtained Pareto-optimal solutions, their mutual distance in the space of criteria and decision variables were calculated, which allowed to group solutions in the classes. Also analyzed the number of direct neighbors of Pareto-optimal solutions for the purposes of assessing the stability of solutions.

PSEUDOSTATIC DESIGN FACTORS FOR STABILITY OF WATERFRONT-RETAINING WALL DURING EARTHQUAKE

2010 ◽  
Vol 04 (04) ◽  
pp. 387-400 ◽  
Author(s):  
DEEPANKAR CHOUDHURY ◽  
SYED MOHD AHMAD
Keyword(s):  
Retaining Wall ◽  
Pressure Ratio ◽  
Free Water ◽  
Hydrodynamic Pressure ◽  
Wall Friction ◽  
Sliding Stability ◽  
The Stability ◽  
Seismic Forces ◽  
Design Factors ◽  
Similar Kind

The paper presents a methodology for seismic design of rigid watferfront-retaining wall and proposes simple design factors for the sliding stability under seismic condition. Conventional pseudostatic approach has been used for the calculation of the seismic forces, while for the calculation of the hydrodynamic pressure, Westergaard's approach has been used. In addition, the hydrodynamic force has been considered from both the upstream and downstream sides of the waterfront-retaining wall under free water condition of the backfill. Simplified expression for the calculation of the equivalent weight of the wall which would be needed to maintain sliding stability is presented. It has been observed that the presence of water both on the upstream and downstream sides of the wall has serious destabilizing effect on the stability of the wall. It is noticed that as the height of the water inside the backfill increased from 0.00 to a height equal to the height of the wall itself, i.e., the backfill is fully submerged, the weight of the wall needed for the later case is around 3 times more than what would be needed for the former case. Similar observations were also made by varying other parameters like the horizontal and vertical seismic acceleration coefficients, height of the water on the upstream side of the wall, and soil and wall friction angles. The pore pressure ratio and the inclination of the ground, however, did not have significant effect on the results. Due to nonavailability of the results of similar kind in literature, an exact comparison for the present results could not be made. Only partial comparison of the present results is made with an already existing methodology for the dry backfill case only, in which no presence of water has been considered on the other side of the wall. This comparison shows a good agreement with the present results. The proposed pseudostatic design factors for the case of wet backfill with the presence of water on both sides of the wall are claimed to be unique.

A Study of the Lateral Stability of Railroad Vehicles Using a Nonlinear Constrained Multibody Formulation

2001 ◽  
Author(s):  
Davide Valtorta ◽  
Khaled E. Zaazaa ◽  
Ahmed A. Shabana ◽  
Jalil R. Sany
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Linear Theory ◽  
Linear Stability Analysis ◽  
Numerical Study ◽  
Operating Conditions ◽  
Lateral Stability ◽  
Railroad Vehicles ◽  
Contact Formulation ◽  
The Stability

Abstract The lateral stability of railroad vehicles travelling on tangent tracks is one of the important problems that has been the subject of extensive research since the nineteenth century. Early detailed studies of this problem in the twentieth century are the work of Carter and Rocard on the stability of locomotives. The linear theory for the lateral stability analysis has been extensively used in the past and can give good results under certain operating conditions. In this paper, the results obtained using a linear stability analysis are compared with the results obtained using a general nonlinear multibody methodology. In the linear stability analysis, the sources of the instability are investigated using Liapunov’s linear theory and the eigenvalue analysis for a simple wheelset model on a tangent track. The effects of the stiffness of the primary and secondary suspensions on the stability results are investigated. The results obtained for the simple model using the linear approach are compared with the results obtained using a new nonlinear multibody based constrained wheel/rail contact formulation. This comparative numerical study can be used to validate the use of the constrained wheel/rail contact formulation in the study of lateral stability. Similar studies can be used in the future to define the limitations of the linear theory under general operating conditions.

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