• Structural Engineering and Mechanics
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• v.30 no.6
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• pp.651-664
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• 2008

The purpose of this study is to develop a rehabilitation technique for heavily earthquake damaged masonry buildings. A full scale one storey masonry building with window and door openings was manufactured and tested on the shock table by applying increased amplitude free vibration up to the point where heavy earthquake damage was observed. Damaged test building was rehabilitated with vertical and diagonal steel straps and then tested again. The effectiveness of improvements obtained by the rehabilitation technique was investigated. Steel straps improved the lateral strength and stiffness of masonry walls and limited the lateral displacement of building. Stability of the masonry walls were also improved by the steel straps. Steel straps reduced the natural period of the earthquake damaged masonry building and prevented the failure of the building at the same amplitude of free vibration.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.6 s.46
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• pp.31-39
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• 2005

The purpose of this study was to investigate the nonlinear behavior of a cold-formed steel (CFS) shear panel, which was composed of built-up columns and tension-only diagonal straps for bracing, when excited by earthquake motions. For the purpose, shaketable tests of a full-scale two-story cold-formed steel (CFS) shear panel were conducted. in the shear panel, the diagonal strap is a major lateral force resisting system, which is a very ductile member, and the columns, which are gravity resisting members, are fabricated by wooing studs, which can't develop their full flexural strength because they may buckle locally. The test results showed that the straps dissipate most of energy of the shear panel in a tension-only and pinched way and the columns dissipate it relatively smaller than the straps but they still contribute to overall dissipation. As a result of this study, investigating real nonlinear behavior of a structure in earthquakes is a very important process by shaketable tests even though it is simple.

• Structural Engineering and Mechanics
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• v.50 no.2
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• pp.201-214
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• 2014

Due to the confinement effects, Steel-Straps Tensioning Technique (SSTT) can significantly enhance the strength and ductility of high-strength concrete (HSC) members (Moghaddam et al. 2008). However, the enhancement especially in strength may result in slender member and more susceptible to instability (Jiang and Teng 2012a). This instability is particularly significant in HSC member as it inherent the brittle nature of the material (Galano et al. 2008). The current slenderness limit expression used in the design is mainly derived from the experiment and analysis results based on Normal strength concrete (NSC) column and therefore the direct application of these slenderness limit expressions to the HSC column is being questioned. Besides, a particular slenderness limit for the SSTT-confined HSC column which incorporated the pre-tensioned force and multilayers effects is not yet available. Hence, an analytical study was carried out in the view of developing a simple equation in order to determine the slenderness limit for HSC column confined with SSTT. Based on the analytical results, it was concluded that the existing slenderness limit expressions used in the design are appropriate for neither HSC columns nor SSTT-confined HSC columns. In this paper, a slenderness limit expression which has incorporated the SSTT-confinement effects is proposed. The proposed expression can also be applied to unconfined HSC columns.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.12
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• pp.1543-1548
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• 2011

Structural analysis is performed to design anchor straps for a large-scale-liquefied-natural-gas (LNG) storage tank with corner protection and an inner tank by considering structural integrity. Anchor straps made of 9% nickel steel are attached to the inner tank, corner protection, and concrete raft to prevent the failure of the inner tank during both normal and emergency operating conditions. Two finite element (FE) models were analyzed in this study. One is a stand-alone model of the anchor strap, while the other is an extended model of the substructure of the anchor strap, inner tank, and corner protection. Three-dimensional shell elements are used to effectively assess the bending and axial behavior of structures. The Tresca stress values in each part of the two models are calculated for operation under five different load-condition cases: normal operation, leakage of the LNG, hydro test, and two earthquake conditions.

• Earthquakes and Structures
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• v.10 no.1
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• pp.163-178
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• 2016

Composite Lightweight (CL) insulated walls have gained wide adoption recently because the exterior claddings of steel building frames have their cost effectiveness, good thermal and structural efficiency. To investigate the seismic behavior, lateral stiffness, ductility and energy dissipation of steel frames with the CL infill walls, five one-story one-bay steel frames were fabricated and tested under cyclic loads. Test results showed that the bolted connections allow relative movement between CL infill walls and steel frames, enabling the system to exhibit satisfactory performance under lateral loads. Additionally, it is found that the addition of diagonal steel straps to the CL infill wall significantly increases the initial lateral stiffness, load-carrying capacity, ductility and energy dissipation capacity of the system. Furthermore, the test results indicate that the lateral stiffness values of the frames with the CL infill wall are similar to those of the bare steel frames in large lateral displacement.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.3
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• pp.49-57
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• 2014

A deterioration of typical reinforced concrete (RC) bridge deck is due to the use of calcium chloride, cracks and water penetration inside of the deck slab with steel reinforcement. In order to eliminate the defects of RC decks in terms of material, therefore, the steel-strapped deck system is studied and developed by maximizing the arching effect while the girders are restrained using straps in lateral direction to the bridge. This parametric study was performed to analyze the structural characteristics of steel-strapped deck, and to identify the factors of the thickness, span length and lateral restraint stiffness of deck slab considering the concrete non-linearity. Finally, a design equation, which is adequate to South Korea, is suggested.

• 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.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.5
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• pp.137-147
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• 2012

In the steel-free bridge concrete deck, steel straps are generally used instead of conventional steel rebar while laterally restrained in the perpendicular direction to the traffic in order fir the arching effect of concrete deck. In this paper, the minimum amount of FRP bar is to be suggested based on the structural strength, crack propagation, stress level and others in order to control cracks. As a result of laboratory tests, the structural strength of deck with 0.15 percentage of steel strap showed improved structural strength including ductility. The long-term serviceability of steel strap deck with FRP bar proved to satisfy the requirements and to be structurally stable while showing the amount of crack and residual vertical displacement within the allowable limits after two million cyclic loadings. The structural failure of RC bridge deck is generally caused from the punching shear rather than moment. Therefore, the ultimate load at failure could be estimated using the shear strength formula in the two-way slab based on ACI and AASHTO criteria. However the design criteria tend to underestimate the shear strength since they don't consider the arching effects and nonlinear fracture in bridge deck with lateral confinement. In this paper, an equation to estimate the punching shear strength of steel strap deck is to be developed considering the actual failure geometries and effect of lateral confinement by strap while the results are verified in accordance with laboratory tests.