• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.421-426
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• 2006

To examine the behaviors of traditional wooden structural frame in Korea in direction of beam, an experimental study was performed. The interior frame of Daewoongjeon of Bongjeongsa was selected as a model, which has two short exterior columns and one high inside column. The experimental frame has 1/2 scale and lateral forces are applied at high inside column by using drift control. The vertical gravity loads are applied on the frame. From the results of experiment it was shown that the stiffness and lateral capacity of the frame was increased when vertical loads are applied and the force-drift relationship in positive load direction was not same as in negative load direction. And push-over analysis are performed by using macro model in which the rotational and shear springs which were derived from the another experiments of subassemblies were used. The numerical analysis with macro model showed a good correspondence with the experiment within 2% story drift.

• Journal of Korean Society of Steel Construction
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• v.12 no.4 s.47
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• pp.407-416
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• 2000

This paper presents the dynamical responses of the plate girder bridge subjected to moving load by experimental method. The upper slab of the plate girder bridges is modelled to the plate element and the girder to the beam element. The small-scaled vehicle model is manufactured as moving load and the acryl-bridge model as the plate-girder bridge. The dynamic responses of the plate-girder bridges under the moving load are obtained by the strain gauges, displacement measurements, accelerometer, and dynamic strain measurement. The maximum dynamic responses from the measured data are compared with those from the finite element method. The experimental model test can be used to obtain to the dynamic responses of the plate-girder bridges.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.2
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• pp.177-184
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• 2011

In this paper the nonlinear analysis that include time-dependent characteristics of materials and geometric nonlinearity of elements for the cable-stayed PSC bridges is presented. Analysis models for finite element method were developed based on the flexibility based fiber beam-column model originally proposed by Spacone et al.(1996). The developed analysis model implemented in general purpose object-oriented finite element analysis program named HFC(Cho 2009). The performance of proposed analysis models is evaluated by comparing with the former results of the design data. The deflection of time dependent analysis is larger than time ignored analysis on construction sequences, and the bridge is destructed at a smaller deflection than the time ignored analysis on failure behavior.

• Structural Engineering and Mechanics
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• v.84 no.4
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• pp.547-560
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• 2022

By presetting various reinforcement diameters in topology optimization with the discrete model finite element analysis, an algorithm of bidirectional evolutionary structural optimization of multi-level reinforcement diameter is presented to obtain the optimal reinforcement topologies which describe the degree of stress of different parts. The results of a comparative study on different reinforcement feasible domain demonstrate that the more angle types of reinforcement are arranged in the initial domain, the higher utilization rate of reinforcement of the optimal topology becomes. According to the nonlinear finite element analysis of some deep beam examples, the ones designed with the optimization results have a certain advantage in ultimate bearing capacity, although their failure modes are greatly affected by the reinforcement feasible domain. Furthermore, the bearing capacity can be improved when constructional reinforcements are added in the subsequent design. However the adding would change the relative magnitude of the bearing capacity between the normal and inclined section, or the relative magnitude between the flexural and shear capacity within the inclined section, which affects the failure modes of components. Meanwhile, the adding would reduce the deformation capacity of the components as well. It is suggested that the inclined reinforcement and the constructional reinforcement should be added properly to ensure a desired ductile failure mode for components.

• Steel and Composite Structures
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• v.34 no.5
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• pp.715-732
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• 2020

High-strength steel composite Y-eccentrically braced frame (Y-HSS-EBF) is a novel structural system. In this study, the spatial substructure hybrid simulation test (SHST) method is used to further study the seismic performance of Y-HSS-EBF. Firstly, based on the cyclic loading tests of two single-story single-span Y-HSS-EBF planar specimens, a finite element model in OpenSees was verified to provide a reference for the numerical substructure analysis model for the later SHST. Then, the SHST was carried out on the OpenFresco test platform. A three-story spatial Y-HSS-EBF model was taken as the prototype, the top story was taken as the experimental substructure, and the remaining two stories were taken as the numerical substructure to be simulated in OpenSees. According to the test results, the validity of the SHST was verified, and the main seismic performance indexes of the SHST model were analyzed. The results show that, the SHST based on the OpenFresco platform has good stability and accuracy, and the results of the SHST agree well with the global numerical model of the structure. Under strong seismic action, the plastic deformation of Y-HSS-EBF mainly occurs in the shear link, and the beam, beam-columns and braces can basically remain in the elastic state, which is conducive to post-earthquake repair.

• Steel and Composite Structures
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• v.29 no.2
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• pp.231-242
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• 2018

As a lateral load resisting component, buckling restrained steel plate shear walls (BRW) have excellent energy dissipating capacity. Similar to thin steel plate shear walls, the mechanical behavior of BRWs depends on the boundary elements (adjacent beams and columns) which need adequate strength and stiffness to ensure the complete yielding of BRWs and the emergence of expected plastic collapse mechanism of frame. This paper presents a theoretical approach to estimate the design forces for boundary elements of beam-connected BRW (i.e., The BRW is only connected to beams at its top and bottom, without connections to columns) using a fundamental plastic collapse mechanism of frame, a force transferring model of beam-connected BRW and linear beam and column analysis. Furthermore, the design method of boundary beams and columns is presented. The proposed approach does not involve nonlinear analyses, which can be easily and efficiently used to estimate the design forces of beams and columns in a frame with BRWs. The predicted design forces of boundary elements are compared with those from nonlinear finite element analyses, and a good agreement is achieved.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.10
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• pp.120-129
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• 2002

An integrated structure and controller design approach for rotating cantilever beam is presented. An optimization method is developed for improving positioning performance considering the elastic deformations during high speed rotation and adopting the beam shape and the control gains as design variables. For this end, a dynamic model is setup by the finite element method according to the shape of the beam. The mass and stiffness of the beam are distributed in such a way that the closed-loop poles of the control system should be located leftmost in the complex s-plane. For optimization method, the simulated annealing method is employed which has higher probability to find the global minimum than the gradient-based down-hill methods. Sequential design and simultaneous design methods are proposed to obtain the optimal shape and controller. Simulations are performed with new designs by the two methods to verify the effectiveness of the approach and the results show that the settling time is improved for point-to-point position controls.

• Steel and Composite Structures
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• v.29 no.5
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• pp.635-645
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• 2018

Beam-column joints play a significant role in static and dynamic performances of reinforced concrete frame structures. This study contributes a numerical approach of topologically optimal design of carbon fiber reinforced plastics (CFRP) to retrofit existing beam-column connections with crack patterns. In recent, CFRP is used commonly in the rehabilitation and strengthening of concrete members due to the remarkable properties, such as lightweight, anti-corrosion and simplicity to execute construction. With the target to provide an optimal CFRP configuration to effectively retrofit the beam-column connection under semi-failure situation such as given cracks, extended finite element method (X-FEM) is used by combining with multi-material topology optimization (MTO) as a mechanical description approach for strong discontinuity state to mechanically model cracked structures. The well founded mathematical formulation of topology optimization problem for cracked structures by using multiple materials is described in detail in this study. In addition, moved and regularized Heaviside functions (MRHF), that have the role of a filter in multiple materials case, is also considered. The numerical example results illustrated in two cases of beam-column joints with stationary cracks verify the validity, benefit and supremacy of the proposed method.

• Structural Engineering and Mechanics
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• v.92 no.2
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• pp.133-147
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• 2024

Composite beams of steel and concrete strengthened with fiber-reinforced polymers (FRP) may exhibit considerably enhanced flexural behaviour, but the combination of three materials with different characteristics and the various possible failure mechanisms that may govern performance make their analysis quite demanding. Previous studies provided significant insights into this problem and several methods were proposed for calculating flexural stiffness and strength, but these studies are restricted to the single member level of a simply supported composite beam section. However, the problem considerably changes when the beam is part of a frame system due to the degree of continuity provided by the surrounding structure, which represents the most common situation in practice. This paper explores the behaviour of semi-continuous FRP-strengthened composite beams, by considering the response characteristics of their end connections and their effects on overall performance. A novel analytical model is derived, which enables a step-by-step representation of the nonlinear relationship between an incremental mid-span design bending moment and corresponding connection rotations. After verification against finite element analyses, a parametric study is conducted which shows that the substantially increased bending moment resistance of FRP-strengthened composite beams can hardly be fully utilized due to a deficiency of corresponding large deformation capacity available in the connections. The extent to which the presence FRP strengthening can be exploited to enhance the beam flexural response depends on the interplay between various structural parameters, including the connection rotation capacity, the beam span, and the FRP modulus of elasticity and ultimate strength.

• Steel and Composite Structures
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• v.44 no.1
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• pp.33-47
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• 2022

This paper presents a finite element model for predicting the monotonic behaviour of bolted endplate joints connecting steel-concrete composite walls and steel beams. The demountable Hollo-bolts are utilised to facilitate the quick installation and dismantling for replacement and reuse. In the developed model, material and geometric nonlinearities were included. The accuracy of the developed model was assessed by comparing the numerical results with previous experimental tests on hollow/composite column-to-steel beam joints that incorporated endplates and Hollo-bolts. In particular, the Hollo-bolts were modelled with the expanded sleeves involved, and different material properties of the Hollo-bolt shank and sleeves were considered based on the information provided by the manufacture. The developed models, therefore, can be applied in the present study to simulate the wall-to-beam joints with similar structural components and characteristics. Based on the validated model, the authors herein compared the behaviour of wall-to-beam joints of two commonly utilised composite walling systems (Case 1: flat steel plates with headed studs; Case 2: lipped channel section with partition plates). Considering the ease of manufacturing, onsite erection and the pertinent costs, composite walling system with flat steel plates and conventional headed studs (Case 1) was the focus of present study. Specifically, additional headed studs were pre-welded inside the front wall plates to enhance the joint performance. On this basis, a series of parametric studies were conducted to assess the influences of five design parameters on the behaviour of bolted endplate wall-to-beam joints. The initial stiffness, plastic moment capacity, as well as the rotational capacity of the composite wall-to-beam joints based on the numerical analysis were further compared with the current design provision.