• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.5
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• pp.79-83
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• 2006

The present low speed crash regulations and RCAR test for insurance estimate do not tend to reflect car crash occurred on a road. Therefore, car makers are trying to readjust test standard be similar to a real situation. Passenger cars and SUV vehicles on the market will be subject to this study for car to car crash. In addition, we will discuss improvement of test methods for a low speed crash and direction of bumper design by performing this impact analysis.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.1
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• pp.99-104
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• 2010

It is a frequent occurrence in urban traffic - a low-speed collision in which one vehicle hits the back of another. The vehicles often sustain expensive damage. Bumpers can reduce this damage, but only line up so the initial contact in an impact is bumper to bumper. Then the bumpers on the colliding vehicles have to absorb the crash energy, keeping damage away from expensive sheet metal, lights, and other components. In real world accidents, Bumper mismatches in crashes are increasing, and the resulting repair costs from low-speed collisions are escalating. In this study, we investigated the bumper rail height and analyzed their effects on repair cost. Futhermore, Our 16kph front-into-rear crash tests demonstrates bumper mismatch problem.

• Structural Engineering and Mechanics
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• v.67 no.1
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• pp.1-8
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• 2018

Shake table tests performed on five 1:3 reduced scale two story RC moment resisting frames having construction defects, have shown severe joint damageability in deficient RC frames, resulting in joint panels' cover spalling and core concrete crushing. Haunch retrofitting technique was adopted herein to upgrade the seismic resistance of the deficient RC frames. Additional four deficient RC frames were built and retrofitted with steel haunch; both axially stiffer and deformable with energy dissipation, fixed to the beam-column connections to reduce shear demand on joint panels. The as-built and retrofitted frames' seismic response parameters are calculated and compared to evaluate the viability of haunch retrofitting technique. The haunch retrofitting technique increased the lateral stiffness and strength of the structure, resulting in the increase of structure's overstrength. The retrofitting increased response modification factor R by 60% to 100%. Further, the input excitation PGA was correlated with the lateral roof displacement to derive structure response curve that have shown significant resistance of retrofitted models against input excitations. The technique can significantly enhance the seismic performance of deficient RC frames, particularly against the frequent and rare earthquake events, hence, promising for seismic risk mitigation.

• Structural Engineering and Mechanics
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• v.71 no.4
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• pp.445-458
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• 2019

This study mainly aims to assess the performance of soil-structure systems designed by direct displacement-based method coupled with strong column-weak beam design concept through various system identification techniques under strong ground motions. To this end, various system identification methods are employed to evaluate the dynamic characteristics of a structure (i.e., modal frequency, system damping, mode shapes, and plastic hinge formation pattern) under a strong seismic excitation considering soil-structure interaction for different site conditions as specified by ASCE 7-10. The scope of the study narrowed down to the code-complying low- to high-rise steel moment resisting frames with various heights (4, 8, 12, 16-story). The comparison of the result of soil-structure systems with fix-based support condition indicates that the modal frequencies of these systems are highly influenced by the structure heights, specifically for the softer soils. This trend is more significant for higher modes of the system which can considerably dominate the response of structures in which the higher modes have more contribution in dynamic response. Amongst all studied modes of the vibration, the damping ratio estimated for the first mode is relatively the closet to the initial assumed damping ratios. Moreover, it was found that fewer plastic hinges are developed in the structure of soil-structure systems with a softer soil which contradicts the general expectation of higher damageability of such structural systems.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.1
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• pp.9-16
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• 1991

The concept of damage is all-pervasive in structural engineering. It can be considered a state variable and defined to vary from 0(no damage) to 1(failure). Thus, the factor of safety against failure, the most important aspect of a structure, cannot be assessed without evaluating the damageability of a structure under load. It is the objective of the research reported herein to study the behavior of concrete under repeated load applications. Concrete is known to deteriorate under such loading, i.e., it suffers damage of increasing degree. Its response to future loading is a function of the amount of damage sustained during previous load exposures. The same can be said about reinforced concrete members and entire structures, but here we wish to consider only plain concrete and express some of its material properties as functions of the degree of sustained damage. The work described herein is based on the stipulation that the energy dissipation capacity of plain concrete is a material property and the damage accumulates in direct proportion to the degree to which the energy dissipation capacity is being exhausted, in some analogy to both high- and low-cycle failure behavior of materials.