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Showing 7 results for Lin

M.m. ALinia,
Volume 2, Issue 4 (December 2004)
Abstract

One main factor in design of panels subjected to axial loading is their buckling behaviour. The design of stiffeners in a metal or composite plated structure is the key factor for safety and weight reduction. This work presents a parametric study on the optimal types and geometrical properties of stiffeners in plates under in-plane axial loads. The results show that flanged type (such as T or L) longitudinal stiffeners increase the normal critical stresses by at least 28% compared to non-flanged stiffener. It is also shown that the optimum geometric properties of stiffeners correspond to the point when the buckling shape of a plate changes from the overall to local mode. Also it is illustrated that for these optimal instances, there always is a linear relationship between the cross-sectional area ratio and the rigidity ratio of the stiffeners to the plates. Finally, Sample relationships for plates having different number of stiffeners are presented.
A.r. Rahai, M.m. ALinia, S.m.f Salehi,
Volume 7, Issue 1 (March 2009)
Abstract

Concentric bracing is one of the most common lateral load resistant systems in building frames, and are

applied to many structures due to their manufacturing simplicity and economics. An important deficiency in the

bracing members is their irregular hysteretic loops under cyclic loading. In order to overcome this problem, it is

advised to restrain braces against buckling under compression, since buckling restrained frames dissipate a large

amount of energy. One method to restrain braces against buckling is to cover them with concrete. A proper covering

can prevent the core from buckling and provide similar capacities whether in tension or compression which would

produce regular hysteric curves. In this study, the behavior of buckling restrained braces (BRB) has been investigated

by considering different types of surrounding covers. The steel core is encased in concrete with different coverings. The

covering types include steel tubes, PVC pipes, and FRP rolled sheets. Experimental and numerical analyses were

implemented. According to the results, PVC pipes and FRP sheets are suitable alternatives to steel pipes. Furthermore,

the behavior of several types of steel cores was assessed since, applying steel with high ductility promotes the energy

dissipation of the brace. Finally, the effect of the separating layer between the steel core and the concrete on the

performance of bracing was evaluated.


Y.y. Chang, C.j. Lee, W.c. Huang, W.j. Huang, M.l. Lin, W.y. Hung, Y. H. Lin,
Volume 11, Issue 2 (Transaction B: Geotechnical Engineering 2013)
Abstract

This study presents a series of physical model tests and numerical simulations using PFC2D (both with a dip slip angle=60° and

a soil bed thickness of 0.2 m in model scale)at the acceleration conditions of 1g, 40g, and 80 g to model reverse faulting. The soil

deposits in prototype scale have thicknesses of 0.2 m, 8 m, and 16 m, respectively. This study also investigates the evolution of a

surface deformation profile and the propagation of subsurface rupture traces through overlying sand. This study proposes a

methodology for calibrating the micromechanical material parameters used in the numerical simulation based on the measured

surface settlements of the tested sand bed in the self-weight consolidation stage. The test results show that steeper surface slope

on the surface deformation profile, a wider shear band on the major faulting-induced distortion zone, and more faulting appeared

in the shallower depths in the 1-g reverse faulting model test than in the tests involving higher-g levels. The surface deformation

profile measured from the higher-g physical modeling and that calculated from numerical modeling show good agreement. The

width of the shear band obtained from the numerical simulation was slightly wider than that from the physical modeling at the

same g-levels and the position of the shear band moved an offset of 15 mm in model scale to the footwall compared with the results

of physical modeling.


Shuai Li, Jian-Min Zhang, Wei-Lin Xu, Jian-Gang Chen, Yong Peng, Jun-Ning Li, Xiao-Long He,
Volume 14, Issue 1 (Transaction A: Civil Engineering 2016)
Abstract

The cavitation erosion induced by high flow velocities is very prominent in high head and large unit discharge tunnel. Air entrainment is an effective technology to solve this problem. In this study, numerical simulation and physical model test are applied to the comparative study of air-water flows on bottom and lateral aerator in tunnel. The flow pattern, aeration cavity, air concentration and pressure distribution were obtained and there is a close agreement between the numerical and physical model values. The hydraulic characteristic and aeration effect of anti-arc section are analyzed. The results indicated that added lateral aeration facilities on 1# and 2# aerator can weaken backwater and increase the length of the bottom cavity, but it is limited to improve the air concentration and protect sidewall downstream of the ogee section. Air concentration improved on side walls downstream of anti-arc section when added lateral aeration facility on 3# aerator. The black water triangle zone disappeared and the floor and side walls well protected.


XiaoLing Song, Jiuping Xu, Charles Shen, Feniosky Peña-Mora,
Volume 15, Issue 2 (Transaction A: Civil Engineering 2017)
Abstract

The construction temporary facilities layout planning (CTFLP) requires an identification of necessary construction temporary facilities (CTFs), an identification of candidate locations and a layout of CTFs at candidate locations. The CTFLP is particularly difficult and complex in large-scale construction projects as it affects the overall operation safety and effectiveness. This study proposes a decision making system to decide on an appropriate CTFLP in large-scale construction projects (e.g. dams and power plants) in a comprehensive way. The system is composed of the input, CTF identification, candidate location identification, layout optimization, evaluation and selection, as well as output stages. The fuzzy logic is employed to address the uncertain factors in real-world situations. In the input stage, the knowledge bases for identifying CTFs and candidate locations are determined. Then, CTFs and candidate locations are identified in the following two stages. In the mathematical optimization stage, a multiobjective mathematical optimization model with fuzzy parameters is established and fuzzy simulation-based Genetic Algorithm is proposed to obtain alternative CTFLPs. The intuitionistic fuzzy TOPSIS method is used to evaluate and select the most satisfactory CTFLP, which is output in the last stage. To demonstrate the effectiveness and efficacy of the proposed method, the CTFLP for the construction of a large-scale hydropower dam project is used as a practical application. The results show that the proposed system can assist the contractor to obtain an appropriate CTFLP in a more efficient and effective manner.


Jun Lin, Guojun Cai, Songyu Liu, Anand J. Puppala, Haifeng Zou,
Volume 15, Issue 3 (Transaction B: Geotechnical Engineering 2017)
Abstract

The correlations and relationships between electrical resistivity and geotechnical parameters of soils have become very important for site investigation. However, there is a lack of understanding about the relationships between electrical resistivity and geotechnical parameter values. The resistivity piezocone penetration tests and laboratory tests have been conducted for geotechnical investigations of marine clay in Jiangsu province of China to establish quantitative relationships between electrical and geotechnical data. The geotechnical investigation reveals that electrical resistivity values are very low for marine clay in Jiangsu, ranging from 5 to 10 Ω m. The correlations between electrical resistivity and geotechnical parameters are examined using Spearman’s rank correlation test that is a rank-based test for correlation between two variables without any assumption about the data distribution. It was shown that the electrical resistivity has strong bonds with the moisture content, void ratio, salt content and plasticity index. In terms of quantitative relationships, good fitting relationships between electrical resistivity and selected geotechnical parameters are observed. The statistical analysis indicates that the electrical resistivity is a good indirect predictor of selected geotechnical parameters. The data studied demonstrates the usefulness of the in situ resistivity method in geotechnical investigations, which have an advantage over other geotechnical methods in cost performance.


XiLin Lu,
Volume 15, Issue 6 (Transaction B: Geotechnical Engineering 2017)
Abstract

This paper presents numerical and theoretical studies on the stability of shallow shield tunnel face found in cohesive-frictional soil. The minimum limit support pressure was determined by superposition method; it was calculated by multiplying soil cohesion, surcharge load, and soil weight by their corresponding coefficients. The varying characteristics of these coefficients with soil friction angle and tunnel cover-to-diameter ratio were obtained by wedge model and numerical simulation. The face stability of shallow shield tunnel with seepage was studied by deformation and seepage coupled numerical simulation; the constitutive model used in the analysis was elastic-perfectly plastic Mohr–Coulomb model. The failure mode of tunnel face was shown related to water level. By considering the effect of seepage on failure mode, the wedge model was modified to calculate the limit support pressure under seepage condition. The water head around the tunnel face was fitted by an exponential function, and then an analytical solution to the limit support pressure under seepage condition was deduced. The variations in the limit support pressure on strength parameters of soil and water lever compare well with the numerical results. The modified wedge model was employed to analyze the tunnel face stability of Qianjiang cross-river shield tunnel. The influence of tide on the limit support pressure was obtained, and the calculated limit support pressure by the modified wedge model is consistent with the numerical result.



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