Y.Z.Totoev1 and G. Simundic2
- Senior Lecturer, School of Engineering, University of Newcastle, University Drive, Callaghan, NSW, 2308, ceyuri@civeng.newcastle.edu.au
- Professional Officer, School of Engineering, University of Newcastle, goran.simundic@newcastle.edu.au
ABSTRACT
Masonry structures in Australia contain slip joints between concrete slabs and their supporting masonry walls to accommodate differential movements due to concrete slab shrinkage, thermal effects and masonry moisture expansion. Traditionally slip joints consist of one or two layers of membrane type material placed between the masonry and concrete.
According to Australian Standards, all structures must be designed for earthquake loading. Therefore, the slip joints must satisfy two apparently conflicting requirements – slip under long term loads and transmit short term dynamic load through the structure. Tests at the Universities of Newcastle and Adelaide have indicated that these types of joints do exhibit substantial shear capacity under short term load. There is an urgent need to establish their behaviour under long duration induced strains (i.e. differential movement effects) to clarify their potential to behave as slip joints for the serviceability limit state.
Long term drying shrinkage tests have been performed at the University of Newcastle. In these tests the frictional load in the joint between a shrinking concrete slab and a masonry wall was recorded over a three month period. It was found that the low tensile strength of concrete slabs and long test duration limit the applicability of these tests. A new low velocity slip test has been developed. In this test method the concrete slab on the slip joint is pushed at a constant speed by controlled thermal expansion of the calibrated metal rod. Each test takes about ten days. This paper presents a description of the new test and preliminary tests results.
KEYWORDS: slip joint, membrane, shear transfer, differential movement
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