Concrete has been widely used for material of bridge girder. However, Concrete is considered as inefficient material for long-span girder. Because it has low material strength compared with those of steel girder, huge cross sectional area are required to have same strength of steel girder bridges. UHPC(Ultra High Performance Concrete) as new material is developed to supplement this weakness of concrete. UHPC has high compressive strength and show softness behavior due to it is reinforced by fiber. If UHPC has no any reinforcement for shear, diagonal tension crack failure is dominant like normal concrete. So, reinforcement for shear is essential and prestress is efficient method of reinforcement for UHPC due to high compressive strength. However, design equation for shear strength suggested by K-UHPC Certification(2012) do not consider prestress effect. Therefore, this study investigate effect of prestress for shear strength of ultra high performance concrete I-girder by using finite element analysis program

In this study, a quasi-static experiment was conducted on the connection performance between the integral abutment bridge and CFT pile. Six experiment specimen were manufactured and were divided into type A and type B. Experiment specimens of Type A were connected with bolts and experiment specimens of Type B were connected with hooks. In the experiment results the connection performance of Type B showed excellent performance more than that of Type A.

In this study, elastic flange local buckling strength of doubly symmetric I-girder subjected to bending moment were evaluated by 3D finite element analysis. The analysis model were modeled by 3D shell elements(S4R) using ABAQUS 6.13 program. And loading and boundary conditions were determined by equal end moments and simple boundary conditions. Flange and web slenderness ratio were considered in the parametric studies to evaluate flange local buckling strength with AISC design equations. Then, AISC design equations and characteristics of Elastic flange local buckling of I-girder were evaluated.

The initial production scale of wind tower is very few. But recently, the production scale of wind tower structure has increased gradually because it maximizes the efficiency in green energy. Many researchers are studying the wind tower, but there is no study about the difference of allowable buckling stress of the wind tower with and without opening. Guideline of codes and standards are very limited when designing a wind tower with an opening. It is also rarely that a study considers the design of the wind tower to be a tubular shell with or without an opening. ABAQUS, a general purpose finite element program, which provides safety evaluation and economical standards for the design and behavior of the wind tower considering the effect of opening was used in the study. Finally, results from this study can serve as reference for structural engineers, manufacturers and further studies of wind turbine when designing a tubular shell wind tower with an opening.

This study dealt with passenger safety assessment of roadside barrier structures using high anti-corrosion steels, which are called hot-dip zinc-aluminium-magnesium alloy-coated steels. We performed a simulation with high anti-corrosion barriers capable of absorbing impacts and calculated the breakage stress to assess passenger safety. Passenger safety was assessed by calculating the THIV (Theoretical Head Impact Velocity) and PHD (Post-Impact Head Deceleration). This process compares normal steel materials and high anti-corrosion steel materials. The simulation test results for the roadside barriers built with high strength anti-corrosion steels with reduced sectional thickness meet the safety evaluation criteria, hence the proposed roadside barrier made by high strength and high anti-corrosion hot-dip zinc-aluminium-magnesium alloy-coated steel will be a good solution to serve passenger safety as well as save maintenance cost and better structural performance.

In this paper, we study the calculation for the damage area of the tension specimens using image processing techniques. This study was able to calculate the area of the damage region on the basis of original image. Generally, to extract the area in the original image, we have to use opening operation, close operation, the Hit-or-Miss operation and bottom hat filter, top hat filter, etc. In particular, to extract the area of the composite specimen discussed in this study, we have to use the combination of the operations and filters because it is non-isotropic material, or should develop a new algorithm based on it.

철근콘크리트 슬라브의 휨강도 보강을 위해 제안된 섬유보강폴리머(Fiber Reinforced Polymer, FRP)와 초 고거동 콘크리트(Ultra High Performance Concrete, UHPC)의 합성구조의 파괴 시 거동을 살펴 본 결과, 과다한 휨 보강으로 인한 전단파괴와 보강된 FRP의 탈착에 의한 파괴가 발생하였다. 전단강도와 휨 강도의 크기를 고려한 설계 기준을 제시하여 휨 보강 한도를 제한하고, 전단 철근을 추가하여 탈착에 의한 파괴를 보강하였다. 휨 강도의 보강을 제한 하고 부착 철근이 보강된 슬라브의 실험 결과, 휨에 의한 연성파괴가 유도되었다.

Earthquakes is impossible to predict and occur within very little or no warning. They cause significant damage to property and inflict large human casualties. Seismic retrofit for non-seismic design RC frame has been studied over the years. Although there are many seismic retrofit methods, the seismic retrofit methods are increased weight and physical damage to structures. This study evaluates the seismic performance of RC frame retrofitted with velcro. The specimens were made scale down of actual steel structures, and displacement loads were applied in the trasnverse direction.

Recently, researches of concrete performance improvement are increased in the advanced countries. Most nano material research is analyzed by experiment. This study performs a numerical analysis used by tensile strength of MWCNT and nano continuum theory, so effect on the performance improvements of nano mortar is analytically confirmed. Preceding researches about experimental result of flexural strength by Chan and Andrawes are comparative verified with result of multi-scale finite element modeling. In addition, parametric studies were conducted to investigate the effect of the ratio of width and the ratio of height on the behavior of proposed finite element modeling by nonlinear finite element analyses.

Displacement response of structure is valuable information for monitoring an structure integrity. However, measuring the displacement response is difficult than other structure responses, such as acceleration, strain, and angle. So, previous researches have focused on displacement estimation technique using measured acceleration. The displacement estimation methods also have weakness that filtering noise of measured data is so complicate. The estimated displacement might be diverged because of the measuring noise. Because of these reasons, this study focused on rotation angle. This study developed a algorithm for estimating displacement and structure deformed shape using rotation angle.

The purpose of this paper is to demonstrate to the practicing engineers, how to apply the advanced composite materials theory to the slab bridges. For general construction material used, there is certain theoretical limit in sizes. For super slab bridges construction, the reduction in panel weight is the first step to take in order to break such size limits. For a typical slab bridges panel, both concrete and advanced composite sandwich panels are considered. The concrete panel is treated as a special orthotropic plate. Advanced composite sandwich panels are considered as a self-weights less than one tenth of that of concrete panel, with deflections less than that of the concrete panel. This conclusion gives good guide line for design of the light weight of slab bridges.

A finite element simulation study was performed to determine influences of different post spaces and thicknesses of crash barriers on the dynamic behaviors due to truck crash. Accuracy of the simulation was verified using qualitative and quantitative comparisons. Based on in-depth examination of crash simulation recordings, energy distributions occurred in the barrier against the car are determined. In this paper, the existing finite element crash analysis of barriers using the LS-DYNA program is further extended to study the dynamic response of the barrier with various geometries of the guardrail. The numerical results for various parameters are verified by comparing different models.

Grate bar is a metal part being used in the sintering process in a steel company. It is exposed to severe operating conditions such as high temperature, corrosion, wear and chemical reaction and etc. In this paper, the surface of the grate bar is coated with high performance materials. They are Al2O3, Cr2O3, WC. These materials have enhanced grate bar’s performances of life time, corrosion, thermal resistance, abrasion, chemical resistance and etc. These high quality characteristics are verified through experimental tests. The results are presented and discussed.

The polyurethane spring, which provides the restoring force for a sliding bridge bearing, governs the overall behavior of the bearing. An analytical model, therefore, which reflects actual geometrical shape and can be utilized easily in engineering practice, is needed to be developed. In this paper, a simplified model for analyzing the polyurethane spring utilized in the sliding bridge bearing is presented. The model is developed for a cylindrical tube based on Gent’s model, and can be utilized for various height-diameter ratios. The accuracy of the proposed model are compared to existing models via experimental data as well as numerical analysis results. The comparison result shows that the proposed model can be used in estimating mechanical behavior of the cylindrical tube shaped polyurethane spring.

The clamping of torque shear high strength bolt is induced when the pin-tail is broken. However the tension forces induced shank of the bolt do not be known by now. This study focused to develop a quantitative method to identify the induced tension by analyzing the electric energy of which electric torque wrench was applied to high strength bolt at the break of pin tail. Based on this co-relation between tension and accumulated current, the regressive analysis was derived. The error rate between tension and accumulated current was 2.24%.

The clamping of torque shear high strength bolt is induced when the pin-tail is broken. However the tension forces induced shank of the bolt do not be known by now. This study focused to develop a quantitative method to identify the induced tension by analyzing the electric energy of which electric torque wrench (rpm 20) was applied to high strength bolt at the break of pin tail. Based on this co-relation between tension and accumulated current, the regressive analysis was derived. The error rate between tension and accumulated current was 5.06%.

This study is about the basic design technology to radically increase the structural stability of structural shell or tube, which are utilized in a variety of large structures like aircrafts, plant, bridges and buildings. Recent studies have revealed that the plates stiffened by closed-sections ribs can be designed to have greater strength as well as the reduction of used number of stiffeners. Then, the analytical models were selected based on the huge steel tube design and the finite element modeling has been conducted using the ABAQUS. Through this study, the elastic buckling strengths are compared with the flat plate buckling stress and the improved effect in the local buckling strength due to the closed-section ribs are numerically verified.