• Proceedings of the Korea Concrete Institute Conference
• /
• 1991.04a
• /
• pp.121-128
• /
• 1991

The changes of stuctural systems in constructing prestressed concrete bridges are investigated according to several construction methods. Based on these investigation, structurally meaningful works are summarized and defined as "Construction Commands". And time-dependent characteristics of concrete and prestressing steels are fully considered. For the static and/or dynamic analysis of three dimensional prestressed concrete bridges at ant construction stages, it is propoesd to use "Comstruction Commands" directly as user's input data. A example of cable syayed bridges is presented by the computer program developed by the present simulation method.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2008.05a
• /
• pp.79-82
• /
• 2008

It has been reported that destruction test by core collection is the most reliable of the structural concrete strength in present building construction field. But it causes low efficiency by damage and cutting in structure due to the core collection. It also has some problems in repairing. Additionally in case of strength test with management specimen, different environment compared to the structure environment cause problems about estimation precise structure strength. Therefore, it is required to develop structure direct strength test that has test values and credibility above the ones obtained by core specimen collection strength test and seasonal specimen test to suggest a reasonable and practical management method of structural concrete.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2009.05b
• /
• pp.49-52
• /
• 2009

This paper aims to evaluate hydration and intensity property of different kind of members and intensity in order to evaluate compressive strength of structural concrete using Joint Separation Test Body(JSTB). In fact it is difficult to test and evaluate already have constructed member. In this case, common method used by construction engineer is that ; Schmidt rebound hammer test, Ultrasonic pulse test, Method of using test specimen previously cast. However, these method to control the structural intensity involve many problem and impossibility to adapt construction. 80, this paper proposes advance an opinion which have proper to examine intensity. has also aims to examine its validity and the plan to make similar environment with structural concrete and joint separation test body in order to verify efficiency assessment and on-site application.

• Journal of the Korea Concrete Institute
• /
• v.29 no.4
• /
• pp.345-351
• /
• 2017

This study evaluated the effectiveness of V-shaped ties as an alternative to the supplementary crossties specified in ACI 318-14 on the flexural ductility of reinforced concrete columns. From column specimens tested under constant axial loads and reversed cyclic lateral loads, the mode of failure and lateral load-lateral displacement relationship were measured according to the variation of the applied axial load levels. After the columns reached the peak lateral load capacity, the $90^{\circ}$ hooks of the crossties gradually opened, which eventually caused premature buckling of the longitudinal reinforcement and severe crushing of the core concrete, whereas no V-ties were extracted from the core concrete until the column failure. As a result, the cumulative work damage indicators up to 80% of the peak lateral load for V-tie columns under the axial load level of 0.2, 0.4, and 0.55 was as much as 2.4, 2.3, and 5.2 times higher, respectively, than those of the companion crosstie columns. The superiority of the V-ties to the conventional crossties in enhancing the flexural ductility of columns became more prominent as the axial load level increases.