• Journal of Korean Association for Spatial Structures
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• v.17 no.3
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• pp.91-98
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• 2017

Most of the cultural assets in Korea are wooden structures. Due to the material characteristics of wood, the preservation of traditional wooden structure is impossible by simple maintenance. Damaged member is replaced with new member or completely dissolve and restore them. But member has a cultural value, so that it is impossible to arbitrarily replace each member. Although the preservation treatment method using synthetic resin is emphasized, there is no exact standard for proper reinforcement ratio. This paper is experimental study for reinforcement ratio of wooden flexural member with synthetic resins, Reinforced ratio on section area of flexural member. As a result, synthetic resin reinforcement are selected as experimental variables by proper ratio enhanced flexural capacity of reinforced wooden member than new wooden member.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.3
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• pp.194-201
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• 2003

This study presents the comparative filtration performance evaluation of automotive fuel filters based on the theory of Beta ratio. For the experiments, the fuel component's test stand incorporating the multi-pass filtration test circuit was developed. A mathematical description of filtration process in general was derived. And the theoretical basis of multi-pass test and the test procedure were described in detail. Experimental results revealed that domestic fuel filter tested could not maintain consistent Beta ratio, that is filtration efficiency, although it had the holding capacity of contaminants close to the specification at maximum pressure drop across the filter assembly. The results of experiments and simulations also showed that filtration system model could be refined including desorption ratio to estimate the variable Beta ratio in service life.

• Steel and Composite Structures
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• v.42 no.2
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• pp.265-275
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• 2022

A new type of precast steel reinforced concrete (PSRC) column was put forward in this paper. In order to study the static performance of PSRC column and hollow precast steel reinforced concrete (HPSRC) column subjected to combined compression and shear loading, a parametric test was carried out and effects of axial compression ratio, concrete strength and shear ratio on the mechanical behavior of composite PSRC column and HPSRC column were explored. In addition, the cracks development, load-span displacement relationship, strain distribution and shear bearing strength of column specimens were emphatically focused. Test results implied that shear failure of all specimens occurred during the test, and higher strength of cast-in-place concrete, smaller shear ratio and larger axial compression ratio could lead to greater shear resistance, but when the axial compression ratio was larger than 0.36, the shear capacity began to decrease gradually. Furthermore, truss-arch model for determining the shear strength of PSRC column and HPSRC column was proposed and the calculated results obtained from proposed method were verified to be valid.

• Steel and Composite Structures
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• v.22 no.2
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• pp.217-234
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• 2016

In order to investigate mechanical properties and load-bearing capacity of T-shaped Concrete-Filled Square Steel Tubular (TCFST) composite columns under eccentric axial load, three T-shaped composite columns were tested under eccentric compression. Experimental results show that failure mode of the columns under eccentric compression was bending buckling of the whole specimen, and mono column performs flexural buckling. Specimens behaved good ductility and load-bearing capacity. Nonlinear finite element analysis was also employed in this investigation. The failure mode, the load-displacement curve and the ultimate bearing capacity of the finite element analysis are in good agreement with the experimental ones. Based on eccentric compression test and parametric finite element analysis, the calculation formula for the equivalent slenderness ratio was proposed and the bearing capacity of TCFST composite columns under eccentric compression was calculated. Results of theoretical calculation, parametric finite element analysis and eccentric compression experiment accord well with each other, which indicates that the theoretical calculation method of the bearing capacity is advisable.

• Earthquakes and Structures
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• v.14 no.3
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• pp.261-271
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• 2018

Fiber reinforced cementitious composites (FRCC) materials that exhibit strain-hardening and multiple cracking properties under tension were recently developed as innovative building materials for construction. This study aims at exploring the use of FRCC on the seismic performance of coupling beams with conventional reinforcement. Experimental tests were conducted on seven FRCC precast coupling beams with small span-to-depth ratios and one ordinary concrete coupling beam for comparison. The crack and failure modes of the specimens under the low cycle reversed loading were observed, and the hysteretic characteristics, deformation capacity, energy dissipation capacity and stiffness degradation were also investigated. The results show that the FRCC coupling beams have good ductility and energy dissipation capacities compared with the ordinary concrete coupling beam. As the confinement stirrups and span-to-depth ratio increase, the deformation capacity and energy dissipation capacity of coupling beams can be improved significantly. Finally, based on the experimental analysis and shear mechanism, a formula for the shear capacity of the coupling beams with small span-to-depth ratios was also presented, and the calculated results agreed well with the experimental results.

• Structural Engineering and Mechanics
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• v.37 no.1
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• pp.39-59
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• 2011

Results of an experimental investigation on the behavior and ultimate shear capacity of 27 reinforced concrete Transfer (deep) beams are summarized. The main variables were percent longitudinal(tension) steel (0.28 to 0.60%), percent horizontal web steel (0.60 to 2.40%), percent vertical steel (0.50to 2.25%), percent orthogonal web steel, shear span-to-depth ratio (1.10 to 3.20) and cube concrete compressive strength (32 MPa to 48 MPa).The span of the beam has been kept constant at 1000 mm with100 mm overhang on either side of the supports. The result of this study shows that the load transfer capacity of transfer (deep) beam with distributed longitudinal reinforcement is increased significantly. Also, the vertical shear reinforcement is more effective than the horizontal reinforcement in increasing the shear capacity as well as to transform the brittle mode of failure in to the ductile mode of failure. It has been observed that the orthogonal web reinforcement is highly influencing parameter to generate the shear capacity of transfer beams as well as its failure modes. Moreover, the results from the experiments have been processed suitably and presented an analytical model for design of transfer beams in high-rise buildings for estimating the shear capacity of beams.

• Earthquakes and Structures
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• v.22 no.6
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• pp.597-608
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• 2022

One of the most important parameters affecting nonlinearsoil-structure interaction, especially rocking foundation, is the vertical factor of safety (F.S_v). In this research, the effect of F.S_v on the behavior of rocking foundations was experimentally investigated. A set of slow, cyclic, horizontal loading tests was conducted on elastic SDOF structures with different shallow foundations. Vertical bearing capacity tests also were conducted to determine the F.S_v more precisely. Furthermore, 10% silt was mixed with the dry sand at a 5% moisture content to reach the minimum apparent cohesion. The results of the vertical bearing capacity tests showed that the bearing capacity coefficients (N_c and N_γ) were influenced by the scaling effect. The results of horizontal cyclic loading tests showed that the trend of increase in capacity was substantially related to the source of nonlinearity and it varied by changing F.S_v. Stiffness degradation was found to occur in the final cycles of loading. The results indicated that the moment capacity and damping ratio of the system in models with lower F.S_v values depended on soil specifications such cohesiveness or non-cohesiveness and were not just a function of F.S_v.

• Steel and Composite Structures
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• v.13 no.1
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• pp.15-33
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• 2012

For an axially loaded box-shaped member, the width-to-thickness ratio of the plate elements preferably should not be greater than 40 for Q235 steel grades in accordance with the Chinese code GB50017-2003. However, in practical engineering the plate width-to-thickness ratio is up to 120, much more than the limiting value. In this paper, a 3D nonlinear finite element model is developed that accounts for both geometrical imperfections and residual stresses and the ultimate capacity of welded built-up box columns, with larger width-to-thickness ratios of 60, 70, 80, and 100, is simulated. At the same time, the interaction buckling strength of these members is determined using the effective width method recommended in the Chinese code GB50018-2002, Eurocode 3 EN1993-1 and American standard ANSI/AISC 360-10 and the direct strength method developed in recent years. The studies show that the finite element model proposed can simulate the behavior of nonlinear buckling of axially loaded box-shaped members very well. The width-to-thickness ratio of the plate elements in welded box section columns can be enlarged up to 100 for Q235 steel grades. Good agreements are observed between the results obtained from the FEM and direct strength method. The modified direct strength method provides a better estimation of the column strength compared to the direct strength method over the full range of plate width-to-thickness ratio. The Chinese code and Eurocode 3 are overly conservative prediction of column capacity while the American standard provides a better prediction and is slightly conservative for b/t = 60. Therefore, it is suggested that the modified direct strength method should be adopted when revising the Chinese code.

• Earthquakes and Structures
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• v.3 no.6
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• pp.821-838
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• 2012

This paper proposes a new three-layer pillar-type hysteretic damper system for residential houses. The proposed vibration control system has braces, upper and lower frames and a damper unit including hysteretic dampers. The proposed vibration control system supplements the weaknesses of the previously proposed post-tensioning vibration control system in the damping efficiency and cumbersomeness of introducing a post-tension. The structural variables employed in the damper design are the stiffness ratio ${\kappa}$, the ductility ratio ${\mu}_a$, and the ratio ${\beta}$ of the damper's shear force to the maximum resistance. The hysteretic dampers are designed so that they exhibit the targeted damping capacity at a specified response amplitude. Element tests of hysteretic dampers are carried out to examine the mechanical property and to compare its restoring-force characteristic with that of the analytical model. Analytical studies using an equivalent linearization method and time-history response analysis are performed to investigate the damping performance of the proposed vibration control system. Free vibration tests using a full-scale model are conducted in order to verify the damping capacity and reliability of the proposed vibration control system. In this paper, the damping capacity of the proposed system is estimated by the logarithmic decrement method for the response amplitudes. The accuracy of the analytical models is evaluated through the comparison of the test results with those of analytical studies.

• Steel and Composite Structures
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• v.38 no.1
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• pp.103-120
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• 2021

This research examines the eccentric compression performance of composite columns composed of recycled aggregate concrete (RAC)-filled square steel tube and profile steel. A total of 17 specimens on the composite columns with different recycled coarse aggregate (RCA) replacement percentage, RAC strength, width to thickness ratio of square steel tube, profile steel ratio, eccentricity and slenderness ratio were subjected to eccentric compression tests. The failure process and characteristic of specimens under eccentric compression loading were observed in detail. The load-lateral deflection curves, load-train curves and strain distribution on the cross section of the composite columns were also obtained and described on the basis of test data. Results corroborate that the failure characteristics and modes of the specimens with different design parameters were basically similar under eccentric compression loads. The compression side of square steel tube yields first, followed by the compression side of profile steel. Finally, the RAC in the columns was crushed and the apparent local bulging of square steel tube was also observed, which meant that the composite column was damaged and failed. The composite columns under eccentric compression loading suffered from typical bending failure. Moreover, the eccentric bearing capacity and deformation of the specimens decreased as the RCA replacement percentage and width to thickness ratio of square steel tube increased, respectively. Slenderness ratio and eccentricity had a significantly adverse effect on the eccentric compression performance of composite columns. But overall, the composite columns generally had high-bearing capacity and good deformation. Meanwhile, the mechanism of the composite columns under eccentric compression loads was also analysed in detail, and the calculation formulas on the eccentric compression capacity of composite columns were proposed via the limit equilibrium analysis method. The calculation results of the eccentric compression capacity of columns are consistent with the test results, which verify the validity of the formulas, and the conclusions can serve as references for the engineering application of this kind of composite columns.