• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.67-74
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• 2010

A variation of temperature acting on a RC roof slab causes a change of stress in concrete since it expands during summer and is compressed during winter. This behavior repeats annually and makes an affection to the structural capacity of member for both serviceability and ultimate level. In this paper, a cyclic temperature loading variation is calculated by analyzing the weather data of Korea for 20 years. In addition, an experimental work is planned to find the long term effect of temperature variation. Six RC slab are made with same dimension. Test parameters are loading duration (10, 20, 30 year) and whether it has pre-damage or not. Observation of stiffness variations according to cyclic loading period shows that the serious stiffness drop happens after 10 year's cyclic loading at summer while after 30 year's loading at winter. From the fracture test about slabs damaged by long term cyclic loading, however, the capacity of member such as initial stiffness and maximum strength were not changed except yield strength according to the period of long term cyclic loading. The yield strength tends to decrease after 20 year's cyclic loading.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.5
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• pp.1-10
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• 2012

This paper presents an experimental result and suggests the confinement effect of headed cross tie in reinforced concrete(RC) columns subjected to cycling horizontal loads under constant axial load. Five RC columns specimens were manufactured, taking confined type of transverse reinforcement, whether or not using cross tie, end detail of cross tie (hooked or headed), and axial stress in column as major variables, Cyclic horizontal load applied to the columns under constant axial stress and the effect of cross tie to structural capacity of column was evaluated from the test. The column without cross tie failed showing bending deformation of hoop with crack in core concrete at low horizontal load while the column with cross tie showed quite improved strength and ductility by suppressing bending deformation of hoop as well as buckling of longitudinal bar at once even after crack in core concrete. At high lateral displacement, the column with hooked cross tie showed the failure pattern loosing the confining force of cross tie since the $90^{\circ}$ hooked part of cross tie was stretched out and the cracked core concrete lumps were came off. However, the column with headed cross tie showed very stable behavior since the head of cross tie effectively confined the hoop and longitudinal bars even at high lateral displacement.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.71-77
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• 2019

Recently, most of the pile foundations have been applied as a method to transfer the heavy load of the structure to the ground with high bearing capacity. In this study, the pile-cap behavior between foundation and hollow-head precast reinforced concrete(HPC) pile reinforced with longitudinal rebar and filling concrete was experimentally evaluated depending on the cyclic load and reinforcement ratio. As the drift ratio increases, it was found that the cracks pattern and fracture behavior of two types of pile-cap specimens according to the reinforcement ratio were evaluated to be similar. As the reinforcement ratio increases by 1.77 times, the BS-H25 specimen increases the maximum load by 1.47 times compared to the BS-H19 specimen. However, the ductility ratio of positive and negative was decreased by 76% and 70% respectively. After the yielding of the pile-cap reinforcing rebars, the positive and negative stiffness of the all specimens were decreased by a range from 66% to 71% and a range from 54% to 57% respectively, and the average stiffness of BS-H25 specimen is 13% higher than that of BS-H19 specimen. The cumulative dissipated energy capacity of BS-H19 and BS-H25 specimen under ultimate load state is 5.5 times and 6.6 times higher than that of service load state.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.4
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• pp.29-36
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• 2010

To investigate the cyclic characteristics of exterior joints in RC frame buildings which are typically used after 1988, 70% scaled T-shaped beam-column subassemblies were designed and tested with a displacement control that is composed of 9 steps, until 3.5% story drift was reached. Axial forces are applied to columns during the experiment to simulate a real situation. The results show that the non-seismic detailed specimens failed before reaching 0.85% story drift, and their strengths are less than 0.85 times the nominal flexural strength which beam or columns should reach. The relationship of principal stress and story drift of exterior joints is similar to the one that Priestly proposed.

• Journal of the Earthquake Engineering Society of Korea
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• v.26 no.6
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• pp.247-253
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• 2022

The columns of older reinforced concrete (RC) buildings generally have limited reinforcement details. Thus, they could be vulnerable to earthquake ground motions, leading to partial or complete building collapse. In this study, high-performance fiber-reinforced cementitious composite (HPFRCC) was applied to RC columns to improve their seismic behavior. Experimental tests were conducted with two full-sized specimens with limited reinforcement details, including short lap splices, while unidirectional loadings were applied to the specimens. The seismic behavior of RC columns was substantially improved by using HPFRCC.

• Journal of the Korea Concrete Institute
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• v.17 no.4 s.88
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• pp.535-542
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• 2005

Two series of experiments on the performance of beam-column joints in High-Strength Reinforced concrete frames were carried out. Main experimental parameters were : concrete strength, column axial load and amount of joint hoop reinforcement. Test result showed that the ultimate shear strength of exterior joints increased of column axial compressive force and the amount of the joint hoop reinforcements. Through the regression analysis on the 24data, the following equation is obtained $jv_u=(2.935{\times}10-3\;{\rho}jw{\cdot}fy\;+\;0.365){\sqrt{f_{ck}}}$

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.1
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• pp.27-34
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• 2012

The objective of this study is to evaluate the stiffness of mortar-filled sleeve bar splice using estimation method of failure mode in the sleeve reinforcement splice. To attain this goal, we analyzed the test results of 261 actual-sized mortar-filled sleeve splice specimens. The study results showed that the estimation method of the failure mode in mortar-filled sleeve bar splice made an effective estimate of the stiffness in this bar splice with the exception of specimens with SD500 bars and smooth pipe sleeve. Especially, of the specimens with cast sleeve or uneven pipe sleeve in the range of reinforcement fracture using the estimation method of the failure mode in mortar-filled sleeve splice, specimens over 98% with SD400 bars and all specimens with SD500 bars had the stiffness capacity of higher than "A" class of AIJ code in monotonic loading. In addition, of the specimens in the range of reinforcement fracture using the estimation method of the failure mode in mortar-filled sleeve splice, all specimens with SD400 bars and SD500 bars had the stiffness capacity of higher than "A" class of AIJ code in cyclic loading.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.3
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• pp.19-28
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• 2018

Key factors that ensure competitiveness of modular unit include consistent high quality and connection condition that ensures high structural performance while minimizing the overall scale of the on-site process. However, it is difficult to evaluate the structural performance of the connection of modular unit, and its structural analysis and design method can be different depending on the connection to its development, which affects the seismic performance of its final design. In particular, securing the seismic performance is the key to designing modular systems of mid-to-high-rise structure. In this paper, therefore, the seismic performance of the modular system with bracket-typed fully restrained moment connections according to stiffness and the shapes of various connection members was evaluated through experimental and analytical methods. To verify the seismic performance, a cyclic loading test of the connection joint of the proposed modular system was conducted. As a result of this study, theoretical values and experimental results were compared with the initial stiffness, hysteresis behavior and maximum bending moment of the modular system. Also, the connection joint was modeled, using the commercial program ANSYS, which was then followed by finite element analysis of the system. According to the results of the experiment, the maximum resisting force of the proposed connection exceeded the theoretical parameters, which indicated that a rigid joint structural performance could be secured. These results almost satisfied the criteria for connection bending strength of special moment frame listed on KBC2016.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.517-526
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• 2023

To avoid arbitrary design and excessive braces of system supports with high reusability in the field, this study aimed to propose connection conditions for the vertical and horizontal joints of the system supports based on performance evaluation. Disk-type and pocket-type connection materials, widely used in domestic construction sites, were selected for evaluation of rotational stiffness based on load directions(vertical and horizontal) and loading methods (monotonic and cyclic). Contrary to the current design standards specifying a rotational stiffness of "0" for connection materials, the experimental results revealed that, contrary to the current design standards specifying a rotational stiffness of "0" for connection materials, all specimens exhibited rotational stiffness values. The maximum rotational stiffness was observed to be 19.624 kNm/rad in specimens subjected to repeated loading in the vertical direction using disk-type connection materials.

• Journal of Korean Society of Steel Construction
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• v.18 no.5
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• pp.607-614
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• 2006

The composite metal deck plate system has been widely used of late for office structures. However, composite floor decks are bored imprudently for installation in building equipment. In this study, experimental investigations of bored composite steel deck slabs were performed to evaluate the flexural capacity of each specimen. The variables set were the shapes and positions of the openings in the composite slabs. The results were analyzed in the form of load-displacement graphs and with respect to the ductility and energy dissipation capacity ofeach specimen to evaluate its structural capacity.