• Earthquakes and Structures
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• v.7 no.5
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• pp.705-718
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• 2014

This paper presents an analytical model for determining the transverse reinforcement required for reinforced concrete exterior beam-column joints subjected to reversed cyclic loading. Although the joint aspect ratio can affect joint shear strength, current design codes do not consider its effects in calculating joint shear strength and the necessary amount of transverse reinforcement. This study re-evaluated previous exterior beam-column joint tests collected from 11 references and showed that the joint shear strength decreases as the joint aspect ratio increases. An analytical model was developed, to quantify the transverse reinforcement required to secure safe load flows in exterior beam-column joints. Comparisons with a database of exterior beam-column joint tests from published literature validated the model. The required sectional ratios of horizontal transverse reinforcement calculated by the proposed model were compared with those specified in ACI 352R-02. More transverse reinforcement is required as the joint aspect ratio increases, or as the ratio of vertical reinforcement decreases; however, ACI 352R-02 specifies a constant transverse reinforcement, regardless of the joint aspect ratio. This reevaluation of test data and the results of the analytical model demonstrate a need for new criteria that take the effects of joint aspect ratio into account in exterior joint design.

• Structural Engineering and Mechanics
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• v.87 no.3
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• pp.255-272
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• 2023

Spatial cable systems can provide more transverse stiffness and torsional stiffness without sacrificing the vertical bearing capacity compared with conventional vertical cable systems, which is quite lucrative for long-span earth-anchored suspension bridges' development. Higher economy highlights the importance of refined form-finding analysis. Meanwhile, the internal connection between the lateral and vertical sags has not yet been specified. Given this, an analytic algorithm of form-finding for the earth-anchored suspension bridge with spatial cables is proposed in this paper. Through the geometric compatibility condition and mechanical equilibrium condition, the expressions for cable segment, the recurrence relationship between catenary parameters and control equations of spatial cable are established. Additionally, the nonlinear general reduced gradient method is introduced into fast and high-precision numerical analysis. Furthermore, the analytic expression of the lateral and vertical sags is deduced and discussed. This is very significant for the space design above the bridge deck and the optimization of the sag-to-span ratio in the preliminary design stage of the bridge. Finally, the proposed method is verified with the aid of two examples, one being an operational self-anchored suspension bridge (with spatial cables and a 260 m main span), and the other being an earth-anchored suspension bridge under design (with spatial cables and a 500 m main span). The necessity of an iterative calculation for hanger tensions on earth-anchored suspension bridges is confirmed. It is further concluded that the main cable and their connected hangers are in very close inclined planes.

• Journal of the Korea Construction Safety Engineering Association
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• s.47
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• pp.56-62
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• 2008

In order to apply the Limit Equilibrium Method generally used for the slope stability analysis to the vertical excavation walls reinforced by soil-nailing, in this study, the Limit Equilibrium Method for the temporary shoring facilities reinforced by soil-nailing was proposed, which is based on the stability for the horizontal displacement. In this study, the relation of the internal friction angles of the ground and the vertical excavation depths was arranged, which is satisfying the stability on the horizontal displacement by using the verification of the Limit Equilibrium Method. And then, the rational reinforcing length of soil-nailing was proposed for the critical areas. In addition, the modified safety ratio satisfying the stability on the horizontal displacement was proposed, when the Limit Equilibrium Method was applied to the vertical excavation walls reinforced by soil-nailing.

• Journal of Korean Association for Spatial Structures
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• v.22 no.1
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• pp.25-32
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• 2022

The seismic behaviors of the arch structure vary according to the rise-span ratio of the arch structure. In this study, the rise-span ratio (H/L) of the example arch structure was set to 1/4, 1/6, and 1/8. And the installation angle of the seismic isolator was set to 15°, 30°, 45°, 60° and 90°. The installation angles of the seismic isolator were set by analyzing the horizontal and vertical reaction forces according to the rise-span ratio of the arch structure. Due to the geometrical and dynamic characteristics of the arch structure, the lower the rise-span ratio, the greater the horizontal reaction force of the static load, but the smaller the horizontal reaction force of the dynamic load. And if the seismic isolator is installed in the direction of the resultant force of the reaction forces caused by the seismic load, the horizontal seismic response becomes small. Also, as the installation angle of the seismic isolator increases, the hysteresis behavior of the seismic isolator shows a plastic behavior, and residual deformation appears even after the seismic load is removed. In the design of seismic isolators for seismic response control of large space structures such as arch structures, horizontal and vertical reaction forces should be considered.

• International Journal of High-Rise Buildings
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• v.9 no.4
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• pp.307-314
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• 2020

High-rise buildings with vertical setback are widely used in practice. From the field investigation of the past earthquakes, it was found that such kind of vertically irregular high-rise building structures easily suffer severe damage during strong earthquakes. This paper presents an extensive study on the earthquake responses of moment-resisting frame structures (MFS) popularly applied in high-rise buildings with vertical setback. Four groups of MFS are designed, including three groups of structures with vertical setback and one group of structures with the lateral stiffness varying along the building height but without vertical setback. The numerical models of the structures are established, and the time history analysis of the structures under different levels of earthquakes is conducted. The earthquake responses of the structures are compared. The influence of the ratio between the horizontal setback dimension and the previous plan dimension, the eccentricity of setback, and the position where the setback occurs on the seismic performance of structures is studied. The rationality of the provisions for the structures with vertical setback specified in the current design codes is checked by the findings from this study.

• Journal of Korean Society of Steel Construction
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• v.20 no.1
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• pp.9-20
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• 2008

It is important to increase the economy and efficiency of the diaphragm of the steel box girder bridge design. In this study, an experimental test is performed in a 4-span steel box girder bridge, which was under constructed according to the dead load of slab concrete and vehicle load. The test result is analyzed to verify the stress distribution of the diaphragm and the middle span. Next, stresses on the vertical stiffener are analyzed according to height. Stresses on the diaphragm with equal height are arranged respectively. Also, the stress distribution of the diaphragm and the middle span. Next, stress on the vertical stiffeners are analyzed according to height. Stresses on the diaphragm with equal height are arranged respectively. Also, the vertical stiffeners in the diaphragm was studied, and using the analyzed results, the proper length of the ratio of vehicle load with curing concrete to vehicle load with asphalt is calculated in each part of the steel box girder bridge. The results provide data that serve as basis for an economical and efficient design for the steel box girder bridge diaphragm.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2A
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• pp.121-129
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• 2010

In this paper, the characteristics of high damping rubber bearing were studied through various prototype test. The characteristics of HDRB were dependent on displacements, repeated cycles, frequencies, vertical pressure, temperature, the capability of shear deformation and the vertical stiffness. The prototype test showed that the displacement was the most governing factor influencing on characteristics of HDRB. The effective stiffness and equivalent damping of HDRB were decreased with displacement, and increased with frequency. The effective stiffness was decreased with high vertical pressure, while the equivalent damping was increased. In which, the equivalent damping was more dependent on the vertical pressure than the effective stiffness. According to the results of this study, more careful examination is required to design the effective stiffness and equivalent damping ratio considering the dependencies of design displacement and exciting velocity.

• Journal of the Korea Concrete Institute
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• v.26 no.4
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• pp.533-543
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• 2014

Currently, composite construction of prestressed Precast Concrete (PC) and Cast-In-Place (CIP) concrete with different concrete strengths are frequently used in the modular construction. However, current design codes do not clearly define shear design methods for such composite beams. In this present study, simply supported prestressed PC-CIP composite beams without vertical shear reinforcement or only with horizontal shear reinforcement were tested to evaluate the effect of prestressing on the shear strength and the shear design method for such composite members. The test variables were the area ratio of PC and CIP concretes, prestressing force, shear span-to-depth ratio, and shear reinforcement ratio. The results showed that the shear strength was increased by the increase of prestressing force and prestressed PC area, and the decrease of shear span-to-depth ratio.

• Journal of the Korean GEO-environmental Society
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• v.24 no.1
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• pp.5-14
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• 2023

In this study, the load transfer characteristics of the base and skin of drilled shafts were analyzed and the load sharing ratio was calculated by performing a load transfer large-scale model test and three-dimensional numerical analysis considering the similarity of drilled shafts, which is the design target. From the linear behavior of drilled shafts shown in the large-scale model test and 3D numerical analysis results, the skin load transition curve for the design conditions of this study was proposed by Baquelin et al., and the base load transition curve was proposed by Baquelin et al. For the horizontal load transition curve, the formula proposed by Reese et al. was confirmed to be appropriate. The test value was slightly larger than the numerical analysis value for the axial load at the rock socketing, but the load sharing ratio at the rock socketing increased, on average, about 27.8% as the vertical load increased. The analysis value of the vertical settlement of the pile head under the vertical load was evaluated to be slightly smaller than the test value, and the maximum vertical settlement of the pile head in the model test and analysis maximum vertical load was 10.6 mm in the test value and 10.0 mm in the analysis value, and the maximum vertical settlement value at the base of the pile was found to be a test value of 2.0 mm and an analysis value of 1.9 mm. The horizontal displacement at the head of the column (ground surface) and the head of the pile during the horizontal load was found to agree relatively well with the test value and the analysis value. As a result of the model soil test, the horizontal load measured at the maximum horizontal displacement of 38.0 mm was evaluated to be 24,713 kN, and the horizontal load in the numerical analysis was evaluated to be 26,073 kN.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.1
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• pp.68-80
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• 2003

The backward extrusion process of titanium alloy with large length to diameter ratio was simulated for different punch and die shape. The process variables such as initial billet shape, interface friction, contacting time and punch velocity were investigated and compared with experimental results. To make more effectively titanium alloy cup shape forging products with vertical wall, a modified die design which can reduce forging load, prevent sticking with punch and minimize material loss was suggested.