• Journal of Korean Society of Steel Construction
• /
• v.24 no.4
• /
• pp.371-382
• /
• 2012

Existing shear wall system may cause ductility fallen to the structure which it is on because relatively weak concrete core would easy to be damaged. In this study, steel hysteresis dampers whose stiffness is higher than existing coupling beam and whose strength is easy to change depending on design load was used in coupling beam. The steel hysteresis damper was proposed for the shape connected in double in series, from this, several static test were conducted to verify structural performance of the damper. FEM analysis was also performed, then design equation were suggested.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.9 no.1
• /
• pp.1-9
• /
• 1985

In-plane tension fatigue tests (R = 0.05) were carried out to investigate the initiation and propagation behaviors of micro-surface-fatigue cracks on smooth surfaces of a mild steel. Also, the investigations of saturated cyclic strain which can be obtained by the fatigue tests have been made via the cyclic strain intensity factor, .DELTA. $K_{\epsilon}$/, for the purpose of unifying two approaches of the study of fatigue; the one approach is based on the fracture mechanics concept and the other on lowcycle fatigue concept. Some of the results are as follows; The growth rate, d(2a)/dN, of small cracks cannot be represented by one straight line as a function of .DELTA.K for various of the nominal stress range, .DELTA..sigma., and is higher than that of a larger through crack. The rearrangement of the d(2a)/dN by .DELTA..epsilon..root..pi.s( = .DELTA. $K_{\epsilon}$/) with the stress range .DELTA..epsilon. in .DELTA.K replaced by .DELTA..epsilon., strain range, gives one straight line of the .DELTA. $K_{\epsilon}$-d(2a)/dN relation for various values of stress range .DELTA.$_{\epsilon}$../.X>../.

• Fire Science and Engineering
• /
• v.21 no.1 s.65
• /
• pp.1-6
• /
• 2007

This paper investigated the fire and smoke behavior in the compounded multiplex theater using FDS with various spacial and boundary conditions to ensure the fire safety of the multiplex. The results showed that more rapid temperature increase and smoke can be induced near the exit door for the lower fire load duo to the horizontal smoke movement. The overuse of fire resistants can generate more smoke while delaying combustion rate, which can give adverse effect to the evacuation. The mal-function of the exhaust fan would obstruct smoke exhaust but also retard the function of sprinkler head.

• Journal of the Society of Disaster Information
• /
• v.11 no.4
• /
• pp.527-533
• /
• 2015

A simplified method for the calculation of dynamic characteristics of initially stressed antisymmetric cross-ply laminated shells is presented in this paper using the natural frequencies under unloading state. The equation of motion of laminated shell with two opposite edges simply supported is investigated on the basis of Rayleigh-Ritz method and Mindlin shell theory with effect of the curvature term. The relationships of the non-dimensional natural frequencies with initial stresses the coeffcients of critical buckling and the boundaries of te dynamic principal instability region can be characterized by the non-dimensional natureal frequencies under unloading state. Numerical examples are presented t verify the simplified equations and to illustrate potential applications of the analysis.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.16 no.1
• /
• pp.87-94
• /
• 2003

A geometric non-linear finite element formulation of CRTS reflector subjected to displacement loads, corresponding to the successional assembly steps of the reflector, is presented in order to determine the initial static equilibrium state based on the displacement incremental method. Parametric analyses of the influence of cables and mechanical properties of the reflector on the shape error between reference and equilibrium surfaces have been studied. These results of the present study are compared with the others using Galerkin mothod and NASS 98 program to demonstrate the feasibility.

• Journal of Sericultural and Entomological Science
• /
• v.14 no.2
• /
• pp.105-112
• /
• 1972

The effects of the stretching speed and the swelling degree of cocoon filaments on load-elongation curve were tested by tensilon with special attachments. The values of breaking strength, elongation at break and initial tensile strength obtained from load elongation curves are summarized as follows; 1. The breaking strength of the swollen cocoon filament appeared to increase at the high stretching speed, while elongation at break decreased. 2. Load-elongation curve became crinkled at the low speed of stretching. It suggests that both slip and break of the macrofibrils may occur in swelling of cocoon bave. 3. Breaking strength appeared to considerably decrease and elongation at break not to increase in swelling test at 9$0^{\circ}C$ for 60 min. 4. The initial tensile strength was influenced by the stretching speed and swelling degree of cocoon filaments.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.24 no.6
• /
• pp.59-66
• /
• 2020

Two octagonal RC bridge columns of small scale model were tested under cyclic lateral load with constant axial load. One in two specimens was solid cross section, the other was hollow cross section. The volumetric ratio of transverse spiral hoop of all specimens is 0.00206. The columns showed flexure-shear failure. Failure behavior and seismic performance were investigated. The test results showed that the structural performance of the hollow specimen such as initial crack pattern, initial stiffness, and energy dissipation performance was comparable to that of the solid specimen, but the lateral strength, ultimate displacement, energy dissipation performance of hollow specimen noticeably decreased after drift ratio of 3%.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.13 no.2 s.54
• /
• pp.153-164
• /
• 2009

In this paper, a method of increasing in load-carrying capacity is shown in two-span steel-concrete composite bridges strengthened by external tendons. An analytic expression for the increment of tendon force under external loads is derived using virtual work method for straight external tendons and a new rating factor equation is proposed. Considering the initial tendon force and its increment under external loads, an analytic procedure has been developed to calculate the number of tendons and the initial tendon force from the proposed rating factor equation. This method is used to verify a validity and rationality for an existing two-span composite steel-concrete bridge.

• Journal of the Korea Concrete Institute
• /
• v.21 no.2
• /
• pp.159-168
• /
• 2009

In this study, strength, stiffness and confinement effect with stress-strain and stress-volumetric strain curves for improved uniaxial compressive behavior of RC circular columns laterally confined with prestressing aramid fiber strap were experimentally investigated. The test variables were the specimens with or without axial reinforcing bar and the number and spacing of strap, prestressing level, the types of reinforcing fiber (CFS, GFS). As a result, the failure type of the columns was very stable and strength increase rate was about 73% comparison with the general RC columns. Moreover, the strain increase rate is very small and the axial displacement confinement effect was very effective compared with existry methods (CFS, GFS), the initial and final lateral confinement effect was excellent.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.10
• /
• pp.1211-1222
• /
• 2011

It is necessary to use prestressed modal analysis to calculate the modal frequencies and mode shapes of a prestressed structure such as a spinning blade, a preloaded structure, or a thermally deformed pipe, because the prestress effect sometimes causes significant changes in the frequencies and mode shapes. When the finite element model under consideration has a very large number of degrees of freedom, repeated prestressed modal analyses for investigating the prestress effects might become too computationally expensive to finish within a reasonable design-process time. To alleviate these computational difficulties, a Krylov subspace-based model order reduction, which reduces the number of degrees of freedom of the original finite element model and speeds up the necessary prestressed modal analysis with the reduced order models (ROMs), is presented. The numerical process for the moment-matching model reduction is performed directly on the full order models (FOMs) (modeled in ANSYS) by the Arnoldi process. To demonstrate the advantages of this approach for performing prestressed modal analysis, the prestressed wheel and the compressor impeller under their high-speed rotation are considered as examples.