• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.161-170
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• 2007

In general, deflection limit criteria of bridge design specifications would have been considered based on the static serviceability and structural stability. Dynamic serviceability induced from bridge vibration, as a comfort limit, actually has not been included in the criteria. Thus, it is necessary for dynamic serviceability to be considered in bridge vibration problems and for comfort limit on vibration to be needed for evaluating dynamic serviceability of bridges. In this paper, comfort limits of bridge structures considering the time duration exposed by vibration were examined with frequency and time dependent comfort limits, and they were evaluated by using the vibration signals measured from the existing bridges. Therefore, it is resulted that the time-dependent comfort limit considering the duration of vibration is an efficient estimate for evaluating dynamic serviceability of bridges.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.10
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• pp.923-935
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• 2007

In general, deflection limit criteria of bridge design specifications would have been considered based on the static serviceability and structural stability. Dynamic serviceability induced from bridge vibration, as a comfort limit, actually has not been included in the criteria. Thus, it is necessary for dynamic serviceability to be considered in bridge vibration problems and for comfort limit on vibration to be needed for evaluating dynamic serviceability of bridges. In this paper, comfort limits of bridge structures considering the time duration exposed by vibration were examined with frequency and time dependent comfort limits, and they were evaluated by using the vibration signals measured from the existing bridges. Therefore, it is resulted that the time-dependent comfort limit considering the duration of vibration is an efficient estimate for evaluating dynamic serviceability of bridges.

• Journal of the Korean Society for Railway
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• v.14 no.6
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• pp.545-554
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• 2011

In order to get dynamic serviceability of a train travelling on a railway bridge, comfort limits with the deflection of bridge and vertical acceleration on car body are proposed in Eurocode, Shinkansen design criteria, The design guideline of the Honam High-speed railway. The design guideline of the Honam High-speed railway has quoted Eurocode. Therefore it is expected that supplementation of comfort limit of railway bridge according to expansion of span length and the improvement traveling speed of trains in the future would relatively fall behind developed countries in railway. Therefore, in order to secure technological competitiveness in world market, the study was conducted to propose the deflection limit based on vibration serviceability of railway bridges that can consider bridge-train interaction and travelling speed increase. The parameter study and bridge-train dynamic interaction analysis was conducted to figure out the correlation of vertical acceleration on car body and bridge displacement according to the increase in travelling speed. Also, the trend of increasing vertical acceleration on car body according to the increase in travelling speed was confirmed, and the amplification coefficient of vertical acceleration on car body was suggested. And the deflection form and vibration of the bridge were assumed to be in harmonic motion, and transfer function and the amplification coefficient were used to develop the dynamic serviceability deflection limit of the high-speed railway bridge as a formula.

• Special Issue of the Society of Naval Architects of Korea
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• 2005.06a
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• pp.63-68
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• 2005

Optimum design of the big brackets is performed through iterated 3-D FE analyses to meet the permissible limits of stress, which consumes an excessive amount of calculation time. Therefore, this study has been prepared to determine rapidly and accurately an optimum size and scantling of the big brackets at the initial design stage. The generalized slope deflection method (GSDM) based on the span point concept is applied to enhance the efficiency of iterated structural analyses. The accuracy and applicability of the present method is verified by comparing with a detail 3-D FE analysis of web frame structures. As an optimization technique, evolution strategies (ES) are applied using discrete design variables for practical design.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.6
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• pp.139-146
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• 2014

Recently, in field of bridge construction, modular technology has been studied to reduce construction period, traffic impact and environmental impact. This study is a part of research related to the modular bridges. The aim of the study is to analyze the structural behavior and evaluate a serviceability for transverse connection of modular slab bridge. A total of four specimens were fabricated. including a control beam for finding the maximum load by static test. And one control beam and two segmental beams were fabricated for cyclic loading test. As the test result, the beams that were introduced 100% of the design prestressing force showed a smaller maximum deflection, residual deflection and crack width than the control beam. The beam for serviceability evaluation was satisfied with structural serviceability limits of the deflection and crack.

• Structural Engineering and Mechanics
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• v.64 no.2
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• pp.173-181
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• 2017

This paper analyzes the influence of the construction process on short- and long-term deflections on a reinforced concrete structure poured on-site by a portable industrialized system. A parametric analysis was carried out by the Finite Elements Method (FEM) that considered: a) type of construction process with reshoring or clearing (partial striking); b) the number of successively shored floors and c) the number of shores used on each floor. All three factors were especially important for the values of short- and long-term deflections, which were highest in the reshoring processes with the lowest number of successively shored floors and the lowest number of shores per floor. Deflections obtained were compared with the limits laid down by ACI 318-14 and as calculated by this code's simplified method. The long-term deflections were seen to be almost double than those obtained by applying the ACI 318-14 code's simplified method and in some cases these deflections were above the established limits. It can thus be concluded that the load history of a building under construction should be taken into account in order to satisfy a structure's in-service conditions and durability.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.04b
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• pp.379-388
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• 2000

This paper describes the application of discretized continuum-type optimality criteria (DCOC) for design of the reinforced concrete T-beams. The cost of construction as objective function which includes the costs of concrete, reinforced steel and formwork is minimized. The design constraints include limits on the maximum deflection in a given span on bending and shear strengths and optimality criteria is given based on the well blown Kuhn-Tucker necessary conditions, followed by an iterative procedure for designs when the design variables are the depth and the steel ratio. The versatility of the DCOC technique has been demonstrated by considering numerical examples which have one and five span RC T-beams.

• Journal of Industrial Technology
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• v.17
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• pp.191-197
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• 1997

For each construction material used, there is certain theoretical limit in sizes. For tall building construction, the reduction in slab weight is the first step to take in order to break such size limits. In this paper, the feasibility of such objective is proven and given by numerical analysis result. For a typical building slab, both concrete and advanced composite sandwich panels are considered. The concrete slab is treated as a special orthotropic plate to obtain more accurate result. Any method may be used to obtain the deflection influence surfaces needed for this vibration analysis. Finite difference method is used for this purpose, in this paper. The influence of the modulus of the foundation on the natural frequency is thoroughly studied.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.902-907
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• 2004

In this paper, a multi-step optimization using a G.A. (Genetic Algorithm) with variable penalty function is introduced to the structural design optimization of a 5-head route machine. Our design procedure consist of two design optimization stage. The first stage of the design optimization is static design optimization. The following stage is dynamic design optimization stage. In the static optimization stage, the static compliance and weight of the structure are minimized simultaneously under some dimensional constraints and deflection limits. On the other hand, the dynamic compliance and the weight of the machine structure are minimized simultaneously in the dynamic design optimization stage. As the results, dynamic compliance of the 5-head router machine was decreased by about 37％ and the weight of the structure was decreased by 4.48％ respectively compared with the simplified structure model.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.485-490
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• 2000

This paper describes the application of discretized continuum-type optimality criteria (DCOC) for minimum-cost design of the reinforced concrete frame structures consisting of beams and columns. The cost of construction as objective function which includes the costs of concrete, reinforced steel and formwork is minimized. The design constraints include limits on the maximum deflection at a prescribed node, bending and shear strengths in beams, uniaxial bending strength of columns according to design codes(CEB/FIP, 1990). In the first stage, only beams with uniform cross-sectional parameters per span are considered. But the steel ratio is allowed to vary freely. The cross-sectional parameters and steel ratio in each column are assumed to be uniform for practical reasons. Optimality criteria is given based on the well known Kuhn-Tucker necessary conditions, followed by an iterative procedure for designs when the design variables are the depth and the steel ratio. The versatility of the DCOC technique has been demonstrated by considering numerical examples which have one-bay four-storey frame.