Title: Bearing Pads for Precast Concrete Buildings
Date: September-October, 1985
Volume: 30
Issue: 5
Page number: 128-154
Author(s): Donald W. Pfeifer, James K. Iverson
https://doi.org/10.15554/pcij.09011985.128.154
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Abstract
A study of elastomeric bearing pads for use in precast concrete building construction was undertaken. This work included a survey of PCI producers to identify problems and practices, and a review of recent literature. Limited laboratory testing on unreinforced chloroprene (Neoprene) pads, and on random oriented fiber and duck layer reinforced elastomeric pads was undertaken with respect to long-term compressive creep, shear-compression, and uniform and nonuniform compression. Parking structures in five cities were inspected to determine actual field performance of bearing pads under out-of-door conditions. As a result of this work, new design recommendations have been provided for use in PCI literature. Bearing pad thickness design has been modified to allow thinner pads with subsequently larger shape factors, generally based upon allowing the pad thickness to be 1.4 times the anticipated movement of the end of the precast member. Previous design concepts generally required 2.0 times the end-of-member movement for the pad thickness. A design chart, based on laboratory tests, for estimating maximum friction forces on small pads is presented. These values are based on the work that illustrates that at compressive stresses over 400 psi (2.8 MPa), slippage of the unreinforced chloroprene and random fiber reinforced pads will occur at lower shear forces than assumed in design practice in the past. A simple fire test to give a preliminary indication that a Neoprene pad contains only chloroprene as its elastomer has been identified.
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