• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.76-79
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• 2004

The use of recycled aggregate concrete is increasing faster than the development of appropriate design recommendations. This paper is making advances in the recycling of waste concrete material for use as recycled aggregate to make secondary concrete product. Using recycled aggregates from demolished concrete, we manufactured concrete blocks to experiment overall performance in feasible performances. This paper reports limited experimental data on the structural performance of shear wall used concrete blocks made in recycled aggregates. Reinforced concrete frame and shear walls were tested to determine their diagonal cracking and ultimate shear behavior. The variable in the test program was the existence of infilled wall used concrete blocks Made in recycled aggregates. Based on the experimental results, Infilled wall has a high influence on the maximum strength and initial stiffness of reinforced concrete frame. Structural performance of specimen WSB1 and WSB2 is quite different from RCF specimen, particularly strength, stiffness and energy dissipation capacity.

• Steel and Composite Structures
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• v.25 no.4
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• pp.505-521
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• 2017

The steel plate shear wall with beam-only connected infill plate (SSW-BO) is an innovative lateral load resisting system consisting of infill plates connected to surrounding beams and separated from the main columns. In this research, the effects of perforation diameter as well as slenderness ratios of infill plates on the hysteresis behavior of SSW-BO systems were studied experimentally. Experimental testing is performed on eight one-sixth scaled one-story SSW-BO specimens with two plate thicknesses and four different circular opening ratios at the center of the panels under fully reversed cyclic quasi-static loading in compliance with the SAC test protocol. Strength, stiffness, ductility and energy absorption were evaluated based on the hysteresis loops. It is found that the systems exhibited stable hysteretic behavior during testing until significant damage in the connection of infill plates to surrounding beams at large drifts. It is also seen that pinching occurred in the hysteresis loops, since the hinge type connections were used as boundaries at four corners of surrounding frames. The strength and initial stiffness degradation of the perforated specimens containing opening ratio of 0.36 compared to the solid one is in the range of 20% to 30% and 40% to 50%, respectively.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.1
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• pp.1-10
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• 2024

For important structures such as nuclear power plants, In-Structure Response Spectrum (ISRS) analysis is essential because it evaluates the safety of equipment and components installed in the structure. Because most structures are asymmetric, the response can be affected by eccentricity. In the case of seismically isolated structures, this effect can be greater due to the difference between the center of mass of the structure and the center of rigidity of the isolator layer. Therefore, eccentricity effects must be considered when designing or evaluating the ISRS of seismically isolated structures. This study investigated the change of the ISRS of an isolated structure by assuming accidental eccentricity. The variables that affect the ISRS of the isolated structure were analyzed to see what additional impact they had due to eccentricity. The ISRS of the seismically isolated structure with eccentricity was amplified more than when there was non-eccentricity, and it was boosted more significantly in specific period ranges depending on the isolator's initial stiffness and seismic intensity. Finally, whether the displacement requirement of isolators can be applied to the variation of the ISRS due to eccentricity in the design code was also examined.

• Steel and Composite Structures
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• v.42 no.3
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• pp.315-323
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• 2022

Shear connectors are key elements that ensure integrity in a composite system. The primary purpose of a shear connector is to bring a high degree of interaction between composite elements. A wide variety of connectors are available for hot-rolled composite construction, connected to the beam through welding. However, with cold-formed members being very thin, welding of shear connectors is not desirable in cold-formed composite constructions. Shear connectors for cold-formed elements are limited in studies as well as in the market. Hence in this study, three different types of shear connectors, namely, single-channel, double channel, and self-tapping screw, were considered, and their performance assessed by the Push-out test as per Eurocode 4. The connection between channel shear connectors and the beam was made using self-tapping screws to avoid welding. The performance of the connectors was analyzed based on their ultimate capacity, characteristic capacity, ductility, and slippage during loading. Strength to weight ratio was also carried out to understand the proposed connectors' suitability for conventional ones. The results showed relatively higher initial stiffness and ductility for double channel connectors than other connectors. Also, self-tapping screws had a higher strength to weight ratio with low ductility.

• Structural Engineering and Mechanics
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• v.61 no.6
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• pp.701-709
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• 2017

Seismic dissipation devices can play a crucial role in mitigating earthquake damages, loss of life and post-event repair and downtime costs. This research investigates the use of ring springs with high-force-to-volume (HF2V) dissipaters to create damage-free, recentring connections and structures. HF2V devices are passive rate-dependent extrusion-based devices with high energy absorption characteristics. Ring springs are passive energy dissipation devices with high self-centring capability to reduce the residual displacements. Dynamic behaviour of a system with nonlinear structural stiffness and supplemental hybrid damping via HF2V devices and ring spring dampers is used to investigate the design space and potential. HF2V devices are modelled with design forces equal to 5% and 10% of seismic weight and ring springs are modelled with loading stiffness values of 20% and 40% of initial structural stiffness and respective unloading stiffness of 7% and 14% of structural stiffness (equivalent to 35% of their loading stiffness). Using a suite of 20 design level earthquake ground motions, nonlinear response spectra for 8 different configurations are generated. Results show up to 50% reduction in peak displacements and greater than 80% reduction in residual displacements of augmented structure compared to the baseline structure. These gains come at a cost of a significant rise in the base shear values up to 200% mainly as a result of the force contributed by the supplemental devices.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.209-216
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• 2003

The purpose of this study is to investigate the response characteristics of pushover analysis of upper wall-lower frame system with X and Y-directions' lateral load Pushover analysis estimates initial elastic stiffness, post-yielding stiffness, and plastic hinges on each story of structures through three-dimensional nonlinear analysis program. The conclusions of this study are as follows; (1) As a result of pushover analysis, the magnitude of nonlinear response and distribution of yield hinge in lower structure are similar with both X and Y directions, but not in upper structure because of different relative stiffness. (2) The maximum drift ratio of roof is larger for X-direction than for Y-direction with respect to magnitude of shear wall areas in upper structure.

• Smart Structures and Systems
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• v.23 no.2
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• pp.107-122
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• 2019

As one of the most important parameters in structural health monitoring, structural frequency has many advantages, such as convenient to be measured, high precision, and insensitive to noise. In addition, frequency-change-ratio based method had been validated to have the ability to identify the damage occurrence and location. However, building a precise enough finite elemental model (FEM) for the test structure is still a huge challenge for this frequency-change-ratio based damage detection technique. In order to overcome this disadvantage and extend the application for frequencies in structural health monitoring area, a novel method was developed in this paper by combining the cross-model cross-mode (CMCM) model updating algorithm with the frequency-change-ratio based method. At first, assuming the physical parameters, including the element mass and stiffness, of the test structure had been known with a certain value, then an initial to-be-updated model with these assumed parameters was constructed according to the typical mass and stiffness distribution characteristic of shear buildings. After that, this to-be-updated model was updated using CMCM algorithm by combining with the measured frequencies of the actual structure when no damage was introduced. Thus, this updated model was regarded as a representation of the FEM model of actual structure, because their modal information were almost the same. Finally, based on this updated model, the frequency-change-ratio based method can be further proceed to realize the damage detection and localization. In order to verify the effectiveness of the developed method, a four-level shear building was numerically simulated and two actual shear structures, including a three-level shear model and an eight-story frame, were experimentally test in laboratory, and all the test results demonstrate that the developed method can identify the structural damage occurrence and location effectively, even only very limited modal frequencies of the test structure were provided.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1995.04a
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• pp.45-52
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• 1995

The stability and integrity of precast large panel structures are analyzed with nonlinear mathematical model considering the inelastic properties of horizontal joints. In this research, an analysis for cyclic loading test was carried out by the macro model that idealized the horizontal joints as inelastic-nonlinear spring systems. As a results, the strain hardening ratio of shear slip element was estimated as about 0.05%- 0.2% of initial shear stiffness. And under lateral load, the rocking motion due ti overturning moment was dominant rather than shear slip motion in the behavior of precast structures.

• Structural Engineering and Mechanics
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• v.5 no.5
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• pp.625-634
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• 1997

Reinforced concrete (RC) interior beam-column joints with high-strength materials: concrete compressive strength of 100 MPa and the yield strength of longitudinal bars of 685 MPa, were analyzed using three-dimensional (3-D) nonlinear finite element method (FEM). Specimen OKJ3 of joint shear failure type was a plane interior joint, and Specimen 12 of beam flexural failure type was a 3-D interior joint with transverse beams. Though the analytical initial stiffness was higher than experimental one, the analytical results gave a good agreement with the test results on the maximum story shear forces, the failure mode.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.567-572
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• 2003

An experimental work is presented to evaluate the retrofit method for improving the flexural capacity of shear walls. Fives shear wall specimens are designed and retrofitted by using carbon fiber materials such as rod, sheet and plate. Cyclic horizontal loads are applied to the specimens under constant axial load, $0.1f_{ck}A_g$. Test result shows that specimens with additional flexural reinforcement have the increased initial stiffness and deformation capacity. However, the strength is not improved as much as expected. This is because that the flexural reinforcement is pulled out from the foundation at the latter half of cycles. In order to maximize the flexural retrofit, therefore, it is required to study the anchorage behavior of the flexural reinforcement for retrofit.