Introduction

Designers of bridges and other large structures always incorporate bearings which provide for movements and rotations in accordance with the appropriate design codes and Bearing Technologies (BT) have a wide range of products to cater for these requirements.

However, the need to accomodate movements in buildings and slabs is frequently overlooked or underestimated which results in cracking, spalling and sometimes more severe damage to the structure.

Bearing Technologies Strip Bearings are specially designed to avoid the development of cracks and damage to supporting walls, piers and slabs resulting from shrinkage, expansion and eccentric loading effects.

Design

As a leader in the field of Structural Bearing technology, BT has developed this series of bearings to provide simple, cost effective solutions to obviate the problems outlined above.

The provision of some form of ductile element between structural members is not a new concept and dates to Roman times. Traditionally lead sheet, malthoid, timber and other materials have been used to reduce forces and edge loading (eccentricity) at structural interfaces. These materials are, at least, variable in performance and as structural design becomes more sophisticated it becomes increasingly necessary to employ structural bearings whose performance can be predicted with confidence.

By applying sound design principles for Structural Bearings as prescribed in BS5400 9.1:1983, BT can offer products with finite and constant performance characteristics. This enables structural designers to apply reliable values to resistance forces in their structural analyses.

Applications

BT Strip Bearings are intended for use in long buildings, parking decks, large supported slabs, roof structures, reservoirs and anywhere where loads of up to 300kN/m or point loads of up to 100kN need to be supported. Movements of up to 10mm can be accomodated by BT Strip Bearings, beyond this limit and for higher loads other structural bearing types need to be considered (see back page).

Type BKR-For movements up to +/-3mm (see note below) and loads up to 200kN/m

This type comprises a series of synthetic rubber pads set into a continuous strip of compressible expanded polyethylene of various widths. The horizontal force applied by the shear deflection of the pads (Fs) is counterracted by the friction force between the pad and its contact faces with the structure.

Note: The limiting condition for slippage is approximately:

Fs.Δ = 0,25W where W is actual vertical load (kN/m), Fs is from the table below and Δ is actual displacement

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