• Coupled systems mechanics
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• 제11권4호
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• pp.285-295
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• 2022

Laminated composite plates are utilized extensively in different fields of construction and industry thanks to their advantages such as high stiffness-to-weight ratio. Additionally, they are characterized by their directional properties that permit the designer to optimize their stiffness for specific applications. This paper presents a numerical analysis and optimization study of plates made of composite subjected to low velocity impact. The main aim is to identify the optimum fiber orientations of the composite plates that resist low velocity impact load. First, a three-dimensional finite element model is built using LS DYNA computer software package to perform the impact analyses. The composite plate has been modeled using solid elements. The failure criteria of Tsai-Wu's criterion have been used to control the strength of the composite material. A good agreement has been found between the predicted numerical results and experimental results in the literature which validate the finite element model. Then, an Adaptive Simulated Annealing (ASA) has been used to optimize the response of impacted composite laminate where its objective is to maximize the safety factor by varying the ply angles. The results show that the ASA is robust in the sense that it is capable of predicting the best optimal designs.

• Coupled systems mechanics
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• 제11권4호
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• pp.335-355
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• 2022

It's important to note that the number of studies on the lateral vibration of steel liquid storage tanks has been quite modest in the past. The aim of this research has to look at the variables that affect vibration of storage tanks and to highlight the characteristics of a construction that hasn't received much attention in the literature. The storage tank has pre-sized in the study, and aluminum and steel have chosen as components. The specified material qualities and the factors utilized in the investigation has used to calculate vibration frequency values. The resulting calculations are backed up by tables and graphs, and it's an important to look into the parameters that affect the vibration frequencies that will occur on the designed storage tank vary. In the literature, water tanks are usually modelled as lumped masses. The horizontal stiffness of the column on which it is placed is assumed to be constant throughout. This is an approximation method of solving this problem. The column is handled in this study with a more realistic approach that fits the continuum mechanics in the analysis. The reservoir part is incorporated directly into the problem as the boundary condition.

• Advances in concrete construction
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• 제16권2호
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• pp.119-126
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• 2023

Steel fiber reinforced self-compacting concrete (SFRSCC) has good workability such as high flowability and good cohesiveness. The workability, compressive strength, splitting tensile strength, and anti-penetration characteristics of three kinds of SFRSCC were investigated in this paper. The fraction of steel fibers of the SFRSCC is 0.5%, 1.5% and 2.0% respectively. The results of the static tests show that the splitting tensile strength increases with the increase of fraction of steel fibers, while the compressive strength of 1.5% SFRSCC is lowest. It is demonstrated that the anti-penetration ability of 1.5% SFRSCC subjected to a velocity projectile (200-500 m/s) is better than 0.5% and 2.0% SFRSCC according to the experimental results. Considering the steel fiber effects, the existing formula is revised to predict penetration depth, and it is revealed that the revised predicted depth of penetration is in good agreement with the experimental results. The conclusion of this paper is helpful to the experimental investigations and engineering application.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1994년도 가을 학술발표회 논문집
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• pp.79-86
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• 1994

Two case studies on the application of Pile Driving Analyzer (PDA) are introduced. It is shown that the PDA and CAPWAP are effective tools for the construction control of pile foundations with minimum cost and time. The PDA and CAPWAP techniques are able to evaluate the performace of hammer and driving system: to check the stresses in the pile due to driving: to determine the damage of pile: to predict the ultimate bearing capacity of pile: to estimate the important soil paramaters such as the soil resistance, quake, and damping etc.: and to provide the load - displacement curve from the simulated static load test. Theoretical backgrounds of wave mechanics is briefly reviewed and the methodology of construction control using the PDA is also discussed.

• Structural Engineering and Mechanics
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• 제8권5호
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• pp.477-490
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• 1999

The uncertainties associated with structural parameters and dynamic loading are identified and discussed. Structural parametric uncertainties are treated as random variables and dynamic wind load is simulated as a random process. Dynamic wind-induced responses of structures with parametric uncertainties are investigated by using stochastic finite element method. The formulas for structural dynamic reliability analysis considering the randomness of structural resistance and loading are proposed. Two numerical examples of high-rise structures are presented to illustrate the proposed methodology. The calculated results demonstrate that the variation in structural parameters indeed influences the dynamic response and the first passage probability evaluation of structures.

• 터널과지하공간
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• 제2권2호
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• pp.190-198
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• 1992

This study is to summarize the contents for the investigation and design of the construction for oil storage. Since underground caverns are large scale, in their construction one should consider the mechanical stability of caverns and the economic view of construction. On the basis of them, cavern's section and layout were determined and water curtains were designed to maintain hydraulic equilibrium so that gases were sealed tightly. Also the supporting criterial for rock bolt and stotcrete were determined by means of the classification of rock masses and the results of finite element method. The criteria of grouting reinforcement were presented according to the results of injection test in the pilot holes of working face.

• 터널과지하공간
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• 제4권1호
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• pp.47-54
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• 1994

NATM has been applied most of tunnel design and construction in Korea these days. But, if you observe the tunnel designing method and construction conditions, you can see that the NATM isn's usually the most suitable to Korean geology. Also most of engineers feel that it is necessary to understand the NATM correctly adn to introduce another tunnelling principle which can be applied more economically and safely. So, we'd like to introduce a new tunnelling concept. Norwegian Method of Tunnelling(NMT) by comparing the NATM. The main character of NMT is that the forward prediction of conditions and the support of tunnel is done through geological investigation in details. And it can be compared with NATM, in which the support pattern is decided by monitoring of tunnel deformation on the construction.

• Structural Engineering and Mechanics
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• 제16권4호
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• pp.441-468
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• 2003

This paper investigates the structural behavior of modular falsework system under sequential pattern loads. Based on the studies of 25 construction sites, the pattern load sequence modeling is defined as models R (rectangle), L and U. The study focuses on the system critical loads, regions of largest reaction forces, discrepancy between the pattern load and the uniform load, and the warning-system plan. The analysis results show that the critical loads of modular falsework systems with sequential pattern loads are very close to those with the uniform load used in design. The regions of largest reaction forces are smaller than those calculated by the uniform load. However, the regions of largest reaction forces of three models under sequential pattern loads can be considered as the crucial positions of warning-system based on the measured index of loading. The positions of the sensors for the warning-system for these three different models are not identical.

• Structural Engineering and Mechanics
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• 제42권1호
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• pp.55-72
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• 2012

Precast-cast insitu concrete bridge construction is widely practiced for small to medium span structures. These bridges consist of precast pre-stressed concrete beams of various cross-sections with a cast in-situ reinforced concrete slab. The connection between the beams and the slab is via shear links often included during the manufacturing process of the beams. This form of construction is attractive as it provides for standardisation, reduced formwork and construction time. The assessment of the integrity of shear connectors in existing bridges is a major challenge. A procedure for assessment of shear connectors based on vibration testing and finite element model updating is proposed. The technique is applied successfully to a scaled model bridge model and an existing bridge structure.

• Structural Engineering and Mechanics
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• 제26권3호
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• pp.277-295
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• 2007

3-D wall panels are used in construction of exterior and interior bearing and non-load bearing walls and floors of building of all types of construction. Fast construction, thermal insulation, reduced labor expense and weight saving are the most well pronounced advantage of such precast system. When the structural performance is concerned, the main disadvantage of 3D panel, when used as floor slab, is their brittleness in flexure. The current study focuses on upgrading ductility and load carrying capacity of 3D slabs in two different ways; using additional tension reinforcement, and inserting a longitudinal concentrated beam. The research is carried on both experimentally and numerically. The structural performance in terms of load carrying capacity and flexural ductility are discussed in details. The obtained results could give better understanding and design consideration of such prefabricated system.