• Structural Engineering and Mechanics
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• v.48 no.5
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• pp.681-695
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• 2013

Performance-based seismic design allows a structure to develop inelastic response during earthquakes. This modern seismic design requires more clearly defined levels of inelastic response. The ultimate deformation of a structure without total collapse (target displacement) is used to obtain the inelastic deformation capacity (inelastic performance). The inelastic performance of a structure indicates its performance under excitation. In this study, a new energy-based method to obtain the target displacement for reinforced concrete frames under cyclic loading is proposed. Concrete structures were analyzed using nonlinear static (pushover) analysis and cyclic loading. Failure of structures under cyclic loading was controlled and the new method was tested to obtain target displacement. In this method, the capacity energy absorption of the structures for both pushover and cyclic analyses were considered to be equal. The results were compared with FEMA-356, which confirmed the accuracy of the proposed method.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.189-196
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• 2002

The capacity of CFS piers has not been used to a practical design, because there is no guide of a seismic design for CFS piers. Therefore, the guide of a seismic design value is derived from tests of CFS piers in order to apply it to a practical seismic design. Steel piers and concrete-filled steel piers are tested with constant axial load using quasi-static cyclic lateral load to check ductile capacity and using the real Kobe ground motion of pseudo-dynamic test to verify seismic performance. The results prove that CFS piers have more satisfactory ductility and strength than steel piers and relatively large hysteretic damping in dynamic behaviors. The seismic performance of steel and CFS piers is quantified on the basis of the test results. These results are evaluated through comparison of both the response modification factor method by elastic response spectrum and the performance-based design method by capacity spectrum and demand spectrum using effective viscous damping. The response modification factor of CFS piers is presented to apply in seismic design on a basis of this evaluation for a seismic performance.

• Journal of the Korea Concrete Institute
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• v.12 no.4
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• pp.121-130
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• 2000

Current engineering practice in determining sectional dimensions of prestressed concrete (PSC) girders for bridges is primarily based on the code-specified allowable concrete stresses at different loading stages. It is customary that tendons and sectional dimensions are calibrated and tendon forces are applied at once at the initial stage to keep the subsequent stresses occurring at different loading stages within the allowable stresses. This traditional tensioning method, however, usually results in a too conservative sectional depth in view of ultimate capacity of a girder. A new design method which can realize the reduction of sectional depth of PSC girders is theoretically suggested in this study. Tendons are tensioned twice at different loading stages: the initial stage and the stage after fresh slab concrete is cast. It can be shown that according to this technique, sectional depth can be significantly reduced and larger span can be realized compared to traditional ones. Parametric studies are performed with due considerations given to its practical applications.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.187-192
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• 2003

Nowadays, It has adapted both Ultimate Strength Design(USD) and Allowable Stress Design(ASD) Method evaluating load-carrying capacity of PSC I Type Girder Bridge. But it has confused because the each method has brought some different results. This study shows some results of loading test of the PSC I type Girder Bridge and analyzed the structural behavior by FEM analysis considering material nonlinear. Parametric study of effective prestress of post tendon is performed and compared to results of loading test.

• Steel and Composite Structures
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• v.51 no.2
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• pp.117-126
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• 2024

There are many challenges in the construction of large-section tunnels, such as extremely soft rock and fractured zones. In order to solve these problems, the confined concrete support technology is proposed to control the surrounding rocks. The large-scale laboratory test is carried out to clarify mechanical behaviours of the combined confined concrete and traditional I-steel arches. The test results show that the bearing capacity of combined confined concrete arch is 3217.5 kN, which is 3.12 times that of the combined I-steel arch. The optimum design method is proposed to select reasonable design parameters for confined concrete arch. The parametric finite element (FE) analysis is carried out to study the effect of the design factors via optimum design method. The steel pipe wall thickness and the longitudinal connection ring spacing have a significant effect on the bearing capacity of the combined confined concrete arch. Based on the above research, the confined concrete support technology is applied on site. The field monitoring results shows that the arch has an excellent control effect on the surrounding rock deformation. The results of this research provide a reference for the support design of surrounding rocks in large-section tunnels.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.485-497
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• 2024

Ring beam is the main anchorage zone of the tendons in the nuclear power prestressed concrete containment vessel (PCCV). Its safety is crucial and has a great influence on the overall performance of PCCV. In this paper, two half-scale ring beams were tested to investigate the mechanical performance of the anchorage zone in the PCCV under multidirectional pressure. The effect of working condition with different tension sequences was investigated. Additionally, a half axisymmetric plane model of the containment was established by the finite element simulation to further predict the experimental responses and propose the local reinforcement design in the anchorage zone of the ring beam. The results showed that the ultimate load of the specimens under both working conditions was greater than the nominal ultimate tensile force. The original reinforcement design could meet the bearing capacity requirements, but there was still room for optimization. The ring beam was generally under pressure in the anchorage area, while the splitting force appeared in the under-anchor area, and the spalling force appeared in the corner area of the tooth block, which could be targeted for local strengthening design.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.301-304
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• 2006

This study was performed to suggest a theoretical method of flexural capacity of 'Hybrid Beam'. Since the center of 'Hybrid Beam' is composed of embedded composite beam section, a theoretical method of embedded composite beam could be applied to estimation of flexural capacity of 'Hybrid Beam'. In this study, a theoretical evaluation method for flexural capacity of embedded composite beam, which is suggested by KBC 2005, is chosen and its applicability is evaluates as comparing theoretical results with experimental results. In results, for estimation of theoretical ultimate strength, it is proper method that both effects due to concrete and rebar are considered and whole section is assumed to be plastic. and for estimation of theoretical strength at yielding stste, it is proper to apply allowable stress design.

• Steel and Composite Structures
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• v.1 no.3
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• pp.329-340
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• 2001

Cyclic response of "shear" connections between steel outrigger beams and reinforced concrete core walls is presented in this paper. The connections investigated in this paper consisted of a shear tab welded onto a plate that was connected to the core walls through multiple headed studs. The experimental data from six specimens point to a capacity larger than the design value. However, the mode of failure was through pullout of the embedded plate, or fracture of the weld between the studs and plate. Such brittle modes of failure need to be avoided through proper design. A capacity design method based on dissipating the input energy through yielding and fracture of the shear tab was developed. This approach requires a good understanding of the expected capacity of headed studs under combined gravity shear and cyclic axial load (tension and compression). A model was developed and verified against test results from six specimens. A specimen designed based on the proposed design methodology performed very well, and the connection did not fail until shear tab fractured after extensive yielding. The proposed design method is recommended for design of outrigger beam-wall connections.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.301-306
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• 2008

The present seismic analysis of Road-Bridge Design Standard is on a basis of load-vased analysis which lets structures have the strength over load. In this study, the capacity spectrum method, a kind of displacement based method, which is evaluated by displacement of structure, is presented as an alternative to the analysis method based on load. Seismic capacity is performed about the existing reinforced concrete pier which has already secured seismic design by capacity spectrum method. As a result, capacity spectrum method could realistically evaluate the non-elastic behavior of structures easilly and quickly and the displacement of structures for variable ground motion level. And it could efficiently apply to an evaluation of seismic capacity about the existing structures and a verification of design for capacity target of the structure. We propose the seisemic performance method by using the Finite Element Analysis Program.

• Structural Engineering and Mechanics
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• v.59 no.5
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• pp.853-866
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• 2016

This paper examines a methodology for computing the probability of structural failure of reinforced concrete beams subjected to fire. The significant load variables considered are dead load, sustained live load and fire temperature. Resistance is expressed in terms of moment capacity with random variables taken as yield strength of steel, concrete class (or grade of concrete), beam width and depth. The flexural capacity is determined based on the design equations recommended in Indian standard IS456:2000. Simplified method named $500^{\circ}C$ isotherm method detailed in Eurocode 2 is incorporated for fire design. A transient thermal analysis is conducted using finite element software ANSYS$^{(R)}$ Release15. Reliability is evaluated from the initial state to 4h of fire exposure based on the first order reliability method (FORM). A procedure is coded in MATLAB for finding the reliability index. This procedure is validated with available literature. The effect of various parameters like effective cover, yield strength of steel, grade of concrete, distribution of reinforcement bars and aggregate type on reliability indices are studied. Parameters like effective cover of concrete, yield strength of steel has a significant effect on reliability of beams. Different failure modes like limit state of flexure and limit state of shear are checked.