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Structural Research Series 369PDF


Title:Flexural Strength Of Reinforced Concrete Slabs With Externally Applied In-Plane Forces;
Strength Of Slabs Subjected To Multiaxial Bending And Compression
Author(s):Girolami, A.G.; Sozen, M.A.; Gamble, W.L.; Gamble, W.L.; Flug, H.; Sozen, M.A.
Subject(s):Concrete slabs --Testing
Reinforced concrete --Testing
Abstract:Summary of Flexural Strength Of Reinforced Concrete Slabs With Externally Applied In-Plane Forces by Girolaml, A.G.: Reinforced concrete slabs, bounded by elements which can develop horizontal reactions, have flexural capacities considerably in excess of the load calculated by an orthodox application of the yield-line analysis. The additional capacity results primarily from changes in geometry of the slab which generates in-plane forces reacting against the bounding element. Calculation of the effect of the in-plane forces on slab flexural strength is essential for a realistic evaluation of the slab capacity because the increase in load caused by the in-plane forces is not negligible, especially for short-time loading. The investigation described in this report was concerned with the development of a simple method of calculation for the flexural strength of reinforced concrete slabs with in-plane forces and to check the applicability of the method by experiments. Six reinforced concrete slabs with spandrel beams were built, instrumented, and tested. The test slabs, which were six-ft square and 1.75 in. deep, were reinforced with intermediate grade steel ( yield stress was approximately 48,000 psl ) and the concrete strength was approximately 4500:psl.. The slab and the spandrel beams had both negative and positive moment reinforcement to stimulate an interior panel in a two-way slab designed to carry 150 psf. Three of the test slabs were supported only at the corners while three were supported at several points along the spandrel beams to investigate the effects of nonyielding beams... Summary of Strength Of Slabs Subjected To Multiaxial Bending And Compression by Gamble, W.L.: Reinforced concrete slab panels which are supported so that horizontal displacement of the edges of the panels are prevented are often capable of supporting considerably more load than would be indicated by simple yield-line analysis methods because of in-plane compression forces developed during deflection. The purpose of the series of tests and analysis described in this report was to demonstrate that the basic principles used in predicting the strength of reinforced concrete elements subjected to bending moments and thrusts in one direction, as in the case of columns, can also be used satisfactorily to predict the strength and behavior of slabs subjected to bending and in-plane forces acting in several directions at once. The importance of the in-plane forces can perhaps be best illustrated by reference to a set of tests conducted by Ockleston on a large reinforced concrete building. A single interior beam-supported panel carried a uniformly distributed load of 753 psf. While the computed capacity, using the yield-line analysis technique, was 295 psf. The very high load capacity is attributable to the presence of –in-plane compression forces generated when the surrounding panels restrained the lateral movements of the edges of the load panel. Six hexagonal reinforced concrete slabs were constructed and tested in order to investigate the effects of the reinforcement ratio and magnitude of in-plane forces on the strength and behavior of slabs. The slabs were reinforced with steel having a yield stress of about 50 kips/in. ² and the average concrete strength was about 6,300 1b/in.² The slabs were four in. thick, and the basic hexagon measure about 6 ft 2 in. across flats. The edges of the hexagon were slotted to form loading wings, and the load was applied so as to produce constant bending moments in all directions within a three ft diam. Central portion of the slab...
Issue Date:1970-10
Publisher:University of Illinois Engineering Experiment Station. College of Engineering. University of Illinois at Urbana-Champaign.
Series/Report:Civil Engineering Studies SRS-369
Genre:Technical Report
Description:Flexural strength of reinforced concrete slabs with externally applied in-plane forces, by A. G. Girolami, M. A. Sozen [and] W. L. Gamble; and Strength of slabs subjected to multiaxial bending and compression, by W. L. Gamble, H. Flug [and] M. A. Sozen.
Sponsor:The Departmeent Of Defense Office Of The Secretary Of The Army, Office Of Civil Defense. Contract DAHC 20-67-C-0136, Subcontract 12472 (6300 A-030) US, OCD Work Unit 1127D
Date Available in IDEALS:2010-01-08
Identifier in Online Catalog:668141

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