# Shear Tests on Polyurethane Flexible Joints

## TL;DR

This study examines how polyurethane flexible joints behave under shear stress, finding that higher precompression increases their strength.

## Contribution

The paper provides new empirical data on PM-type polyurethane joints under shear loading and identifies failure mechanisms.

## Key findings

- Increasing precompression increases the ultimate shear load of the joints.
- Failure occurs at the interface between the masonry unit and the flexible joint.
- The initial shear strength was determined to be 0.729 N/mm² with a friction coefficient of 0.14.

## Abstract

This paper investigates the behavior of PM-type polyurethane flexible joints connecting structural components. Although flexible polyurethanes are known for their energy dissipation capacity and ability to accommodate large deformations—particularly under seismic actions—research addressing their performance under shear loading remains limited. The primary objective of this work was to characterize these joints under varying levels of normal stress, identify failure modes, and estimate key mechanical parameters. Nine masonry triplet specimens, composed of concrete units and PM-type polyurethane, were subjected to shear testing using a procedure adapted from EN 1052-3. Tests were carried out at three precompression levels: 0.2, 0.6, and 1.0 N/mm2. Tensile tests were further performed to calibrate material models. The results showed that increasing precompression led to higher ultimate shear loads. All specimens failed due to shear failure at the unit–flexible joint interface, with no damage observed in the masonry units. Based on linear regression following EN 1052-3, the initial shear strength was determined to be 0.729 N/mm2, corresponding to a friction coefficient of 0.14.