International Concrete Abstracts Portal

From exploratory research of reinforced fibrous concrete, it has been shown that fibrous concrete is potentially superior and less costly than the conventional reinforced concrete. The testing program consisted of ten beam column joints with half of these joints containing 1.5 percent by volume of concrete of steel hooked end fibers. The beam column joints were constructed with less hoops than a conventional seismic joint would have, ac-cording to design specifications of the American Concrete Institute code ACI 318-77). In studying the behavior of these beam column joints, two failure conditions were found: 1) critical regions whose inelastic behavior is controlled by bending, and 2) critical regions whose inelastic behavior is controlled by high shear existing in the region. The results of the testing will be described. From the analysis of the results, it can safely be concluded that the hooked end steel fibers in the joint region provided: 1) better bond; 2) better confinement of the concrete; 3) a stiffer member; 4) higher moment capacity; 5) higher shear strength; 6) more ductility; and 7) significant improvement in the energy dissipation capacity than did the plain concrete joint.

This report reviews the methods for predicting creep, shrinkage and temperature effects in concrete structures. It presents the designer with a unified and digested approach to the problem of volume changes in concrete. The individual chapters have been written in such a way that they can be used almost independently from the rest of the report. The report is generally consistent with the ACI Building Code (ACI 318-77) and includes material indicated in the Code, but not specifically defined therein.

A reinforced concrete building may be approximately analyzed as a series of crossing plane frames. The beam-column connections can be modeled using either the lateral-torsional member or equivalent beam width techniques. The lateral-torsion-almember definition and associated frame and member modeling rules which comprise the equivalent frame method of ACI 318-77 were calibrated against tests of real structures while methods of computing effective beam widths are based largely on theoretical analyses of elastic plates. Comparisons of the two methods in analyzing a test building for lateral loads are given. Both methods can be forced to produce computed deflections which agree favorably with test data. However, compatibility of lateral de-flections of separately analyzed parallel frames at the same floor level is not assured. Two methods for forcing compatibility of lateral deflections at each floor level of a building are described and shown to produce computed deflections which compare favorably with test data. Limitations of both equivalent frame and equivalent beam width methods are discussed.