• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.4
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• pp.81-87
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• 2008

In this study, concerns the crashworthiness of the widely used vehicle structure, square thin-walled tubes, which are excellent on the point of the energy absorbing capacity. An experimental investigation was carried out to study the energy absorption characteristics of thin-walled square tubes subjected to dynamic crushing by axial loading to develop the optimum structural members. The impact velocity was tested in the rage $4.698{\sim}8.2m/s$. To efficiently review the collapse characteristics of these sections, the simulation have been carried out using explicit FEM package, LS-DYNA. The solutions compared with results the impact collapse experiment. Here, the controller are introduced to improve and control the absorbed energy of thin-walled square tubes in this paper. To predict and control the energy absorption, we designed it in consideration to the it's influence, height, thickness, wide ratio in this study. When the controller used, the experimental results of crushing of square tubes controlled by the controller's elements showed a good candidate for a controllable energy absorption capability in impact axial crushing.

• Computers and Concrete
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• v.34 no.4
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• pp.393-408
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• 2024

In recent decades the strengthening of reinforced concrete (RC) structural elements using Fiber-reinforced polymer (FRP) has received much attention. The behavior of RC elements can vary from axial compression to pure bending, depending on their loading. When the compressive behavior is dominant, the FRP jacket application is common, but when the flexural behavior is prevalent, the codes consider the FRP jacket ineffective. Codes suggest applying FRP bars or strips as Near-surface Mounted (NSM) or Externally Bonded (EB) in the tensile face to strengthen the beams under flexure. To strengthen the columns in tension-control mode, some researchers have suggested NSM FRP bars in both tension and compression faces alone or with the FRP jacket (hybrid). However, the number of tests that evaluate the pure bending of the strengthened columns as one of the pivotal points of the axial force-moment interaction curve is limited. In this paper, 11 RC elements strengthened using the NSM (in both tension and compression faces) or hybrid method were subjected to bending to assess the effect of the amount and material type of the FRP bar and jacket and the dimensions of the groove. The test results revealed that the NSM method increased the flexural capacity of the members between 10% to 50%. Furthermore, using the hybrid method increased the capacity between 51% to 91%. Finally, an analytical model was presented considering the effect of the NSM FRP bond in different circumstances, and its results were in good agreement with the experimental results.

• Steel and Composite Structures
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• v.22 no.4
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• pp.753-775
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• 2016

This paper aims to investigate the demountability of steel column-baseplate connections subjected to monotonic and cyclic loading. This paper presents the finite element analysis of steel column-baseplate connections under monotonic and cyclic loading. The finite element model takes into account the effects of material and geometric nonlinearities. Bauschinger and pinching effects were also included in the developed model, through which degradation of steel yield strength in cyclic loading can be well simulated. The results obtained from the finite element model are compared with the existing experimental results. It is demonstrated that the finite element model accurately predicts the initial stiffness, ultimate bending moment strength of steel column-baseplate connections. The finite element model is utilised to examine the effects of axial load, baseplate thickness, anchor bolt diameter and position on the behaviour of steel column-baseplate connections. The effects of various parameters on the demountability of steel column-baseplate connections are investigated. To achieve a demountable and reusable structure, various design parameters need to be considered. Initial stiffness and moment capacity of steel columnbaseplate connections are compared with design strengths from Eurocode 3. The comparison between finite element analysis and Eurocode 3 indicates that predictions of initial stiffness for semi-rigid connections should be developed and improved design of the connections needs to be used in engineering practice.

• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.3
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• pp.115-123
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• 2017

To investigate the cyclic characteristics of the retrofitted exterior joints of RC frame with haunch, 70% scaled 6 beam-column exterior joint subassemblies were designed according to design guideline according to 1988 and tested with cyclic loading up to 3.5% story drift ratio. During the experiments axial forces are applied to columns to simulate gravity load. Experimental results shows that the strength of retrofitted specimens was increased steadily until 2.5% story drift ratio and their strengths increased more than 1.7 times of the non-retrofitted in case that main bar was bent away from exterior joint. The joint strength and effective stiffness of the retrofitted specimen was increased and results in more deformation capacity compared to the non-retrofitted.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.191-196
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• 2001

The structural performance of a shear wall subjected to lateral loads is influenced by many factors, such as sectional shape, aspect ratio, vertical and horizontal reinforcement, lateral confinement and axial compression, etc. This experimental research is focusing to investigate the structural performance of T-shaped walls with different confining reinforcement. Experimental results show that all specimens finally failed by the crushing of the concrete in the compression zone. Although the location and content of the lateral confinement is different, the results are very similar during the negative loading direction where the flange is compressed. However, when flange is subjected to tension, the location and content of the lateral confinement results in a large difference in the structural performance of T-shaped walls. Therefore, selection of location and content of the lateral confinement would be important aspect in the design of the nonsymmetric structural walls.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.692-695
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• 2004

Seismic performance of reinforced concrete(RC) column bent piers to bidirectional seismic loadings was investigated experimentally. RC column bent piers represent one of the most popular forms of piers used in highway bridges. Further to series of previous experimental researches for the performance of single bridge columns subjected to seismic loadings, four column bent piers were constructed in 400 mm diameter and 2,000 mm height. Each pier has two circular supporting columns. These piers were tested under lateral load reversals with axial load of $0.1f_{ck}A_g$. Bidirectional lateral loadings were applied. The test parameters included: different transverse reinforcement contents and lap-spliced longitudinal reinforcing steels. Test results indicate that lap-splices of longitudinal reinforcing steels have significantly influence on hysteretic response of column bent piers. Column capacity changed with the level of transverse confinement, and bidirectional repeated loadings induced more strength and stiffness degradation than unidirectional repeated loading.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.102-105
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• 2006

Nowadays, increase of demands on efficient utilization of resources while construction process stimulates structural engineers to select remodeling to improve old buildings. To analyze the effects of openings that may be installed in the course of remodeling old buildings, an experimental research was carried out using four approximately half scale of specimens subjected to constant axial forces, and cyclic loading to simulate seismic conditions. Consequently, the existence of opening was verified to induce different observed damages, which caused by reduction of compression strut support formed on the surface of wall. Especially, the maximum force was revealed to decrease approximately 35% as openings were existed. As this tendency was appeared with stiffness and energy dissipation capacity.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.453-456
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• 2003

This research is to evaluate the seismic performance of reinforced concrete bridge piers with lap-spliced longitudinal reinforcement steels in the plastic hinge region, and to develop the enhancement scheme of their seismic capacity. Six circular columns of 0.6m diameter and 1.5m height were made with two confinement steel ratios. They were damaged under series of artificial earthquakes that could be compatible in Korean peninsula. Directly after the pseudo-dynamic test, damaged columns were retested under inelastic reversal cyclic loading simultaneously under an axial load, P=$0.1f_{ck}A_{g}$, and residual seismic performance of damaged columns was evaluated. Test results show that RC bridge piers with lap-spliced longitudinal steels behaved with minor damage even under artificial earthquakes with 0.22g PGA, but failed at low ductility subjected to the subsequent quasi-static load test. This failure was due to the debonding of the lap splice. The specimens externally wrapped with composite FRP straps in the potential plastic hinge region showed significant improvement both in flexural strength and displacement ductility.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.3
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• pp.118-126
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• 1993

Static and dynamic crushing behaviors of composite box tube show the difference with those of metal tube. This paper investigates the characteristics of static and dynamic crushing test which were conducted to characterize the energy absorption and collapse mode of composite box tubes. Sixteen kinds of tube specimens were fabricated from[0/90] woven Glass/Epoxy fabric and autoclave cured. Axial crushing tests were performed using Instron and Dynatup Impact Tester. It is shown that collapse mode and energy absorption capacity can vary according to the aspect ratio, length, loading rate, lay-up direction of fabric, and trigger geometry of the composite box tube.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.1
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• pp.71-77
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• 2016

In this study, the seismic performance of connections between filled composite beam (CG beams) and forming angle composite (FAC) column was experimentally evaluated. First, the bending tests were conducted on two CG beams and the axial tests were conducted on two FAC columns. Then, based on these preliminary test results, the cyclic loading test were performed on two interior connections between CG beam and FAC column. The main difference of two specimens is the plate shape of the CG beam. The test results showed that both specimens achieved the maximum story drift capacity over 0.04 radian which is required for special moment frame.