• Proceedings of the Korea Concrete Institute Conference
• /
• 1995.04a
• /
• pp.293-298
• /
• 1995

The strength of shear connectors embedded in lightweight concrete slab with deck plate is influenced by various factors of deck plate, shear conncetor and concrete. Generally, it is reported that the strength of shear connector in lightweight concrete decreases in comparison with that in normal concrete. So this paper is to use compressive strength of lilghtweight concrete, width-height ratio of deck plate, and cross sectional area of shear conncetor as variables, to evaluate the strength of shear conncetors in composite beam of steel and lilghtweight concrete slabs with deck plate, and then to suggest the reasonable strength equation by comparing the push-out test results with establixhed strength formula. As the result of 24 specimens test, in case of lightweight concrete slab with deck plate, it has showed that in the same strength, the strength of shear connector decreased about 10~20% in comparison with that in normal concrete. In spite of lightweight concrete, the test results were closely approached the established strength formula of shear connector using Fisher's reduction coefficient.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.449-450
• /
• 2009

In this study, the characteristics of initial shear strength of hollow sectional columns were investigated by experiments with parameters of the aspect ratios, void ratios, web area ratios and load patterns. The test results were analyzed with comparison of the values expected by the empirical equations. The empirical equation was newly proposed on the basis of mechanical characteristics and test results, and its validity was evaluated.

• Steel and Composite Structures
• /
• v.19 no.6
• /
• pp.1599-1610
• /
• 2015

Cold Formed Steel members are widely used in today's construction industry. However the structural behavior of light gauge high strength cold formed steel sections characterized by various buckling modes are not yet fully understood. Because of their simple forming and easy connections, the commonly used cold formed sections for beams are C and Z. However both these sections suffer from certain buckling modes. To achieve much improved structural performance of cold formed sections for beams both in terms of strength and stiffness, it is important to either delay or completely eliminate their various modes of buckling. This paper presents various innovative sectional profiles and stiffening arrangements for cold formed steel beams which would successfully contribute in delaying or eliminating various modes of premature buckling, thus considerably improving the load carrying capacity as well as stiffness characteristics of such innovative cold formed sections compared to conventional cold formed steel sections commonly used for beams.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.17 no.1
• /
• pp.11-18
• /
• 1980

In the conventional ship's structures, the stiffeners with asymmetric sections have been widely used, in spite of the disadvantage on the point of strength, compared to those with symmetric sections. So far, the stiffened plating was usually analyzed not considering the geometric unsymmetry characteristics of the section, including only the cross sectional area and moment of inertia. In this paper, the stiffened plating is devided into the strips having a thin-walled open cross section by using the concept of the effective width. The geometric characteristics of the sections are also included. The governing equations are derived, which can be applied to the arbitrary cross section beams, and the symmetric and the asymmetric section beams which have the same cross sectional areas are analyzed by using the finite element method. From that result, we obtain the allowable load of the two sections, and compared them.

• Journal of Korean Society of Steel Construction
• /
• v.10 no.2 s.35
• /
• pp.153-160
• /
• 1998

The sectional dimensions and initial crookedness of the RHS(rectangular hollow section, ${\boxe}-75{\times}75{\times}3.2,\;{\boxe}-100{\times}100{\times}4.2,\;{\boxe}-125{\times}125{\times}6.0$) were measured. The axial compressive strength tests for columns with slenderness $46{\sim}84$ were performed as well as stub tests and tensile tests. FEM analysis was also used. The measurement shows that the errors of sectional dimensions are negligible. For the column length corresponding to ${\lambda}=100$, the initial crookedness with the 2.5% probability estimated from the measured results is 1/490, 1/1121 1/1395 for each section respectively. The yield strengths obtained from tensile test are higher than the specified minimum value by more than 30%. The column test shows that the maximum axial resistances are almost same as, or a little higher than the FEM results and the specified strength curves of AISC Specification and Eurocode, when the maximum strengths from the stub tests are used as the yield strength of the steel. But the test results show much higher column strength than those specified in the Standard and Code, when the specified minimum yield strength of the steel is used.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2009.05b
• /
• pp.65-68
• /
• 2009

Recently, as architectural concrete structures become high-rise and megastructured, concrete become high-strengthened and, by ensuring products of more stability, and rationalization of construction are required.large cross-sectional precast concrete members such as columns show large temperature increase in manufacturing process not only by external heating but also by concrete itself's hydration heating. Therefore, it is expected that specimen for management to predict strength and compression strength of precast concrete member shows different strength characteristics. Concerning this, in order to suggest strength characteristics of high strength mass concrete suitable for precast concrete application, this study comprises the inclusive investigations on the relations between core strength and the strength characteristics per member cross-section dimensional value and per water-bonding material ratio value.

• Journal of the Korean Society for Heat Treatment
• /
• v.26 no.2
• /
• pp.59-65
• /
• 2013

The microstructures and hardness distributions of a large-sized high strength H-sectional steel with both V and Nb were systematically examined. The outer surface of the flange part was composed of martensite and bainite due to faster cooling, and had a high hardness value of approximately 310 Hv. However, the amounts of ferrite and pearlite increased and the hardness decreased with increasing the distance from the outer surface at the flange part, except the inner surface. High hardness value of about 290 Hv was measured at the upper surface of the web part having martensite and bainite. The hardness drastically decreased with increasing the web thickness, and then greatly rose again at the lower surface due to bainite formation caused by fast air cooling. The hardness of the flange part was higher than that of the web part due to the larger amount of low-temperature transformed phases, except for the lower surface of the web part. Nb-rich precipitates of 30 to 50 nm and V-rich precipitates less than 20 nm were observed at both flange and web parts. However, the particle size was smaller at the flange part than the web part, resulting in the higher strength of the flange part.

• Steel and Composite Structures
• /
• v.34 no.3
• /
• pp.333-345
• /
• 2020

In the past, many efficient profiles have been developed for cold-formed steel (CFS) members by judicious intermediate stiffening of the cross-sections, and they have shown improved structural performance over conventional CFS sections. Most of this research work was based on numerical modelling, thus lacking any experimental evidence of the efficiency of these sections. To fulfill this requirement, experimental studies were conducted in this study, on efficient intermediately stiffened CFS sections in flexure, which will result in easy and simple fabrication. Two series of built-up sections, open sections (OS) and box sections (BS), were fabricated and tested under four-point loading with same cross-sectional area. Test strengths, modes of failure, deformed shapes, load vs. mid-span displacements and geometric imperfections were measured and reported. The design strengths were quantified using North American Standards and Indian Standards for cold-formed steel structures. This study confirmed that efficient profiling of CFS sections can improve both the strength and stiffness performance by up to 90%. Closed sections showed better strength performance whereas open sections showed better stiffness performance.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.11a
• /
• pp.517-520
• /
• 2004

Concrete Filled steel Tube pipe structure is a rational type of structure that maximizes performance by combining the strong points of steel frame and concrete. In the structure, the confining effect of steel pipes increases the bearing power of infilled concrete and the strengthening of local bucking of steel pipes by infilled concrete increases the bearing power of members. and these result in the reduction of cross-sectional area and high transformation capacity. Moreover. the structure is economically efficient and widely applicable that it is used from super-high buildings to residential, business and apartment buildings. It enables the construction of multi-story buildings with long spans using columns of small cross-sectional area. In case of diaphragm, however, it is difficult to confirm the compactness of the closed inside of steel pipes. The present study examined the properties of super-high strength concrete over 80MPa by comparing it with 40MPa concrete through heat conductivity and length change tests based on a mixture ratio satisfying the mixture goal presented in the guideline for the design and construction of concrete-filled steel pipe structure. and evaluated the performance of super-high strength concrete according to the shape and size of the aperture ratio of diaphragm.

• Computers and Concrete
• /
• v.32 no.4
• /
• pp.351-363
• /
• 2023

Reducing the self-weight of reinforced concrete structures problem is discussed in this paper by using two types of self-weight reduction, the first is by using lightweight coarse aggregate (crushed brick) and the second is by using styropor block. Experimental and Numerical studies are conducted on (LWAC) lightweight aggregate reinforced concrete slabs, having styropor blocks with various sizes of blocks and the ratio of shear span to the effective depth (a/d). The experimental part included testing eleven lightweight concrete one-way simply supported slabs, comprising three as reference slabs (solid slabs) and eight as styropor block slabs (SBS) with a total reduction in cross-sectional area of (43.3% and 49.7%) were considered. The holes were formed by placing styropor at the ineffective concrete zones in resisting the tensile stresses. The length, width, and thickness of specimen dimensions were 1.1 m, 0.6 m, and 0.12 m respectively, except one specimen had a depth of 85 mm (which has a cross-sectional area equal to styropor block slab with a weight reduction of 49.7%). Two shear spans to effective depth ratios (a/d) of (3.125) for load case (A) and (a/d) of (2) for load case (B), (two-line monotonic loads) are considered. The test results showed under loading cases A and B (using minimum shear reinforcement and the reduction in cross-sectional area of styropor block slab by 29.1%) caused an increase in strength capacity by 60.4% and 54.6 % compared to the lightweight reference slab. Also, the best percentage of reduction in cross-sectional area is found to be 49.7%. Numerically, the computer program named (ANSYS) was used to study the behavior of these reinforced concrete slabs by using the finite element method. The results show acceptable agreement with the experimental test results. The average difference between experimental and numerical results is found to be (11.06%) in ultimate strength and (5.33%) in ultimate deflection.