BEHAVIOUR OF THE "CAZALY HANGER" SUBJECTED TO VERTICAL LOADING

Abstract

This paper describes the initial results of a continuing program of research and testing of precast concrete connections conducted at the University of Toronto in co-operation with the Canadian Prestressed Concrete Institute. The purpose of the project was to study the full range of behaviour of the Cazaly hanger connection. A typical beam to column connection is shown in Fig. 1. The Cazaly hanger consists of three components: a cantilevered top bar which supports the unit containing the hanger; a strap which transfers the vertical load to the bottom of the unit and which, in prestressed members, also serves as anchorage zone reinforcement; and top and bottom anchorage dowels. The basic function of the top dowels is to transfer any horizontal force that acts on the connection. Since this first phase of the program considered the effect of vertical loads only, 40 of the 52 hangers tested did not have top dowels. The hangers may be divided into three groups according to the purpose of the tests: 1. A pilot series of eight hangers tested to obtain an insight into the probable modes of failure and the variables which might affect hanger capacity. 2. A series of 38 hangers tested to determine the effects of hanger properties on capacity and to observe the behaviour of hangers under load. 3. Tests of six hangers to study the effects of prestressing on hanger strength. The variables considered in the tests were number and size of bottom dowels, depth of strap, size of strap, concrete strength, ratio of shear span to beam depth, effect of prestress, and position of hanger reaction.