|
Title |
Evaluation of Flexural Performance of Truss Encased Slab with Compression Elements Composed of U-shaped Steel and Filling Concrete under Permanent Load
|
|
Authors |
김문길(Mun-Gil Kim) ; 천성철(Sung-Chul Chun) ; 김영호(Young Ho Kim) |
|
DOI |
https://doi.org/10.4334/JKCI.2020.32.3.233 |
|
Keywords |
지하주차장; 합성구조; 부분 PC; 영구하중 underground parking lot; composite structure; half PC; permanent load |
|
Abstract |
A design procedure for truss encased slab was developed that doesn’t require slab formwork or shoring system and can be applied to parking lots. Truss encased slab is composed of half PC, tension rebar, truss rebar, U-shaped channels, filling concrete, and topping concrete. In the construction stage, the half PC and tension bars resist the tensile force of the lower part, and the U-shaped channels and filling concrete resist the compression force of the upper part. In a service load state, topping concrete and Half PC are combined to act like reinforced concrete beams. Among the flexural, shear and horizontal shear strengths, the smallest strength is determined as the design strength against the factored design load. The flexural tests were conducted to evaluate the performance of the truss encased slab in the service state. The test variables were the presence or absence of voids. Test results show that both specimens showed sufficient ductility behavior and both specimens developed higher strength than expected flexural strength. The average of [actual flexural strength]/[expected flexural strength] ratio is 1.26, and it can be evaluated safely even if the current flexural strength design equations is used. The deflection under the service load is 79 % of the expected deflection, indicating that the serviceability of truss encased slab is excellent. The moment-curvature relations of tests and prediction were compared to investigate the composite behavior of the truss encased slab. Fully composite behavior of the truss encased slab was confirmed by the moment-curvature relations and the location of the neutral axis with varying the load. The developed truss encased slab is believed to secure proper flexural performance for the design load.
|