Determination of composite slab strength using a new elemental test method

Composite slabs utilizing cold-formed profiled steel decks are commonly used for floor systems in steel framed buildings. The behavior and strength of composite slabs are normally controlled by the horizontal shear bond between the steel deck and the concrete. The strength of the horizontal shear bond depends on many factors and it is not possible to provide representative design values that can be applied to all slab conditions a priori. Thus, present design standards require that the design parameters be obtained from full-size bending tests, which are typically one or two deck panels wide and a single span. However, because these full-size tests can be expensive and time consuming, smaller size specimens, referred to as elemental tests, are desirable and have been the subject of a great deal of research. Details for a new elemental test method for composite slab specimens under bending are presented. Test results consisting of maximum applied load, end slips, and failure modes are presented and compared with the results of full-size specimens with similar end details, spans, etc. It is shown that the performance of the elemental test developed in this study is in good agreement with the performance of the full-size specimens. Application of test data to current design specifications is also presented

Phase-locked loop with sideband rejecting properties Patent

Phase locked loop with sideband rejecting properties in continuous wave tracking rada

U. S. Air Force Educational Programs: A Study of Success Lifelong Learning Process and Programs

An applied project presented to the graduate faculty of the School of Education at Morehead State University in partial fulfillment of the requirements for the Degree of Specialist in Education by Henry W. Easterling, Jr. in December of 1977

Web Crippling Strength of Multi-web Steel Deck Sections Subjected to End One Flange Loading

Cold-formed steel deck profiles are extensively used in building construction due to their versatility and economical considerations. Web crippling is one of the failure modes for these multi-web profiles. The 1996-AISI Specification for the Design of Cold-Formed Steel Structural Members provisions for web crippling are believed to be conservative for multi-web deck sections. They are based on unfastened specimens and are limited to the use of decks with certain geometric parameters. The unified web crippling equation of the North American Specification for the Design of Cold-Formed Steel Structural Members (AISI 2001) is also limited to certain geometric parameters. Although it has new web crippling coefficients for different load cases and different end conditions, in the End One Flange Loading case, coefficients for the unfastened configuration were used as a conservative solution for the fastened case because there was no directly applicable test data available in the literature. This paper presents the results of an experimental study on web crippling strength of multiple-web cold-formed steel deck sections subjected to End One Flange (EOF) loading. A total of 78 tests were conducted on deck sections at Virginia Tech. Test specimens lying inside and outside of certain geometric parameters of the specifications were tested with both unrestrained and restrained end conditions. Test specimens lying inside the specification parameters have revealed conservative results in the prediction of web crippling strength using both the AISI(1996) and the draft of the North American Specification (AISI 2001.

Behavior of Complex Hat Shapes Used As Truss Chord Members

Cold-formed steel roof truss systems that use complex hat shape members for both top and bottom chord elements are a growing trend in the North America steel framing industry. When designing cold-formed steel sections, a structural engineer typically tries to improve the local buckling behavior of the coldformed steel elements. The complex hat shape has proven to limit the negative influence of local buckling. However, a distortional buckling mode can be the control mode of failure in the design for the chord member with an intermediate un-braced length. The chord member may be subjected to both bending and compressive load because of the continuity of the top and bottom chord members. These members are not typically braced between each panel point in a truss. Numerical analyses using finite strip and finite element procedures were developed to compare with experimental results. A parametric study on geometric imperfection was also conducted to investigate the factors that affect the ultimate strength behavior of a particular complex hat shape. Better understanding of the flexural behavior of these complex hat shapes is necessary to obtain efficient, safe designs of a truss system. The results of these analyses will be presented in the paper

Further Studies of Composite Slab Strength

The results to date of a research program focusing on the strength of composite slabs are described. Full-scale experimental slab tests are compared to strengths calculated using the Steel Deck Institute Composite Deck Design Handbook. Based on the comparisons, recommendations are made for modifications to the calculation procedures

Strength and Stiffness Calculation Procedures for Composite Slabs

Two procedures for calculating the strength and stiffness of composite slabs based on a partial interaction model are introduced. The procedures rely on elemental test results for interfacial and end-anchorage behavior, and thus offer an alternate solution to the m and k method that relies heavily on full scale slab tests. Strength calculations made using the new procedures along with calculations from the Steel Deck Institute procedure are compared to a series of full size composite slab test results