W. Samuel Easterling

Characterization of shear bond stress for design of composite slabs using an improved partial shear connection method

AbstractEurocode 4 design provisions specify two methods for the design of composite slabs, namely the m-k and the partial shear connection (PSC) methods. Currently, the m-k method includes the concrete thickness and the shear span of the slab as variables while the PSC method does not. This has resulted in a better accuracy for the m-k method when slabs with varying dimensions are considered. It is demonstrated in this paper that the horizontal shear bond stress varies with the ratio of shear span to effective depth of slab, defined as the slenderness. To include such an effect, a linear shear bond-slenderness equation is proposed. Using the proposed relationship, a linear interpolation of shear bond strength based on two configurations, determined from the outcomes of the bending tests for compact and slender slabs, has been satisfactorily performed. The shear bond strength obtained from this interpolation can be used in collaboration with the existing PSC method, such that the accuracy of the predictio...

Partially restrained composite beam–girder connections

Abstract Beams in a typical steel framed floor system are assumed to have rotationally pinned supports for the purpose of design. In reality, the connections between beams and girders are not rotationally pinned. The connection rotational restraint is characterized by the moment–rotation behavior. This restraint may be a beneficial attribute that can be considered in design. However, a method for approximating the moment–rotation behavior of the beam–girder connection is required before the beneficial effects of the true connection rotational restraint can be considered in design. An experimental and analytical study of the moment–rotation behavior of composite beam–girder connections is presented in this paper. Eight full-scale connections (four cruciform test setups) were tested experimentally. This experimental data was used to verify a component model that is used to approximate the moment–rotation behavior of the connections. The component model was then used to analyze a variety of connection parameter combinations. The results from this analysis were used to develop a simpler method of approximating the moment–rotation behavior of composite beam–girder connections. Although beam–girder connections were the focus of the study reported in this paper, much of the material described is applicable to composite and bare steel PR frame connections.

Elemental bending test and modeling of shear bond in composite slabs

This paper discusses a new experimental bending test and shear bond modeling of steel deck reinforced concrete (composite) slabs. The objective of experimental work is to develop a new elemental bending test method for evaluating the performance and behavior of composite slabs, and also for determining the shear interaction property for use in numerical analysis. The analytical study is conducted to determine whether data from the small scale tests can be used in the present shear bond (m-k) and Partial Shear Connection (PSC) methods, to predict the strength of the actual slabs, to use the same test data for input in numerical analysis, and to improve the existing PSC design procedure. The results of the study demonstrate that the elemental bending test of composite slab using trapezoidal shape steel deck is feasible as a replacement for the full-size test utilizing the same steel deck. Data from the elemental bending test can be used not only in the existing analytical methods but also in the numerical analysis, thus eliminating the need for separate push off type tests. The improved PSC design procedure is found to be comparable with the m-k method.

Finite element modeling of partially restrained beam-to-girder connections

Publisher Summary This chapter provides an overview of finite element modeling of partially restrained beam-to-girder connections that is currently being used to model the partially restrained beam-to-girder connections. This chapter focuses on a finite element modeling technique that is being used to predict the moment-rotation behavior of various beam-to-girder connections. This method relies heavily on the behavior models of various connection sub-elements—bolts, welds, etc., which are also discussed in detail. Certain simplifications are adopted so that the finite element models do not become excessively complex. First, the three dimensional connection behavior is reduced to a two dimensional problem by ignoring out-of-plane effects. This is a common assumption made in most research that involves connections. Second, the two dimensional problem is then further simplified by using only one dimensional finite elements placed in two dimensional space. The elements used are beam, truss, and non-linear spring elements. Beam elements are used to represent the beam and rigid links. Truss elements are used to represent reinforcing steel, concrete, and steel plates. Non-linear springs are used to represent shear studs, bolts, and welds. Another important assumption in the finite element modeling is that the ability to predict the behavior of the fundamental elements of the connection. These fundamental elements are referred to as sub-elements. The term “elements” has been reserved for connection parts that are combinations of sub-elements, such as a seat angle connection and a reinforced composite slab.

Closure to Determination of Composite Slab Strength Using a New Elemental Test Method by Redzuan Abdullah and W. Samuel Easterling

The objective of the study was to develop a method to test composite slabs using small-scale specimens instead of the usual full-scale specimens that are recommended in most codes of practice. Test 13 in Series 1 was the first trial in which the straps were placed at 150 mm on center. As large vertical separation between the concrete and the steel was observed during this test, it was assumed that this strap spacing might not be effective in preventing the steel web from curling. For the next tests in the same series, straps were placed at 100 mm. Upon comparing the results with the full-scale data, it was found that the capacity matched that found in the full-scale tests. At this point, because the objective of the test had been met, we concluded that there was no need for carrying out additional tests with strap spacing more or less than 100 mm. The restraining effect reached a plateau, as measured by the comparison with full-scale tests, and hence the shear bond strength will not be increased more than the maximum shear bond capacity with fully restrained webs for a particular configuration. Therefore straps at 100 mm are deemed sufficient and are suggested as a general rule, at least as applicable to the type of deck, dimension of the specimen, steel sheet thickness, and strap stiffness that are within the scope of this study.