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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 13 Abstracts search results
Document:
SP161-12
Date:
April 1, 1996
Author(s):
T. S. Lok and J. S. Pei
Publication:
Symposium Papers
Volume:
161
Abstract:
Load-deflection responses of simply-supported (SS) and simply-supported all-round (SSAR) steel fiber reinforced (SFR) concrete square slabs subjected to a central point load have been obtained. The slabs measured 810 mm x 810 mm x 50 mm. The elastic response alone is of particular interest and presented here because this has a major influence on the durability of SFR concrete. Results for each SFR concrete slab are compared with theoretical elastic solutions for both boundary conditions and also with the behavior of identical plain concrete and weldmesh reinforced slabs in each case. A modified depth instead of the full slab thickness is proposed for estimating the elastic response of SFR slabs for the two boundary conditions; the depth effectively reduces the elastic stiffness of the cross section. The limiting load level at which the initial response may be considered as linear is established, but the limiting load is dependent on the behavior of the slab. This limiting load level is compared with results calculated from a modified empirical expression for predicting the load at which first crack is perceived to occur. In the empirical expression, a triangular linear stress block with the modified depth is used. On average, the modified depth is about 0.7 times the overall SFR concrete slab thickness for both the SS and SSAR boundary cases. The influence of fiber type, fiber concentration, and boundary condition on the modified depth is not significant.
DOI:
10.14359/1507
SP161-05
Y. L. Mo and H. C. Lai
Although structures with elastic response are fairly well understood, structures with inelastic response are more difficult to analyze. Furthermore, in studies of inelastic response, attention has generally been paid to the response of reinforced concrete structures with relatively little attention being given to pounding of reinforced concrete buildings. Generally, the mutual collisions, or pounding, result from excessive deflections of adjacent buildings. In this paper, an algorithm is described for computing the pounding response of reinforced concrete buildings. In this situation, the buildings are idealized as two-dimensional multi-degree-of-freedom systems with nonlinear force-deformation characteristics. Collision between adjacent masses can occur at any level and are simulated by means of impact elements. Using real earthquake motions, the effect of deflection is investigated. In this study, the following conclusions are found. 1. Pounding can cause high overstresses, mainly when the colliding buildings have excessive deflections. 2. The code-specified separation distance is adequate to prevent pounding. 3. Pounding problems of adjacent buildings with large difference in mass are common.
10.14359/1443
SP161
Editors: Edward G. Nawy and Debrethann R. Cagley
SP-161 All the papers presented in this publication were reviewed by recognized experts in accordance with the ACI review procedures. It is hoped that designers, constructors, and codifying bodies will be able to draw on the material presented in this volume in conjunction with the ACI 435 Committee Report "Control of Deflection in Concrete Structures", in improving the long-term deflection behavior and performance of concrete constructed facilities.
10.14359/14201
SP161-10
P. R. Chakrabarti
In this project, an attempt is made to study the instantaneous load- deflection behavior of partially prestressed beams with unbonded post- tensioning tendons. Thirty-three beams with the following variables were tested: different mixes of reinforcing and prestressing steel, T-beams and rectangular beams, normal and high-strength concrete, low and high ratios of span/depth, and different effective stresses in tendons. Cracking was observed and deflections measured at precracking and postcracking stages. A suitable method for deflection calculation at precracking and postcracking stages is proposed. The proposed deflections and the deflections obtained by current ACI 318-89/92 code equations are compared with the measured deflections.
10.14359/1503
SP161-11
R. Ganeswaran and B. V. Rangan
Presents the results of a study on long-term deformations of high-strength concrete. Shrinkage and creep deformations of high-strength concretes, as well as deflections of beams and one-way slabs made of high- strength concrete are reported. The measured deformations are compared with the values predicted by the ACI method, the CEB-FIP Model Code, and the Australian Practice. The comparison shows several discrepancies between measured and predicted values.
10.14359/1505
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