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CROSS Safety Report

Failure of prestressed hollowcore units during storage and transport

Report ID: 748 Published: 1 June 2022 Region: CROSS-UK


Overview

A reporter shares their experience of the failure of prestressed hollowcore units during storage and transport.

Key Learning Outcomes

For precast manufacturers and designers:

  • Additional reinforcement may be required in precast concrete units to accommodate forces generated during stripping from the mould, transportation, and final installation

  • Careful consideration should be given to the location of cast-in lifting anchors to ensure excessive cantilevers are not generated during lifting operations

For the construction team:

  • Units should be properly supported on delivery vehicles, when stored on site and for temporary support whilst making adjustments

  • The units should have a prepared level store area of adequate size on site

  • End cantilevers should be minimised and where they do occur they should not be loaded.

Full Report

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Our secure and confidential safety reporting system gives professionals the opportunity to share their experiences to help others. If you would like to know more, please visit the reporting to CROSS-UK page.

A reporter has shared their experience of the failure of prestressed hollowcore units during storage and transport. The units are prestressed on the tension face with none or minimal reinforcement in the compression face.

The reporter states the units must be stored and transported with the whole of the upper surface of the plank in compression i.e. with bearings close to the ends of the units. If the bearings are not close to the ends of the units, a cantilever is developed which generates tension in the top of the units i.e. on the compression surface. If this tensile stress exceeds the tensile capacity of the concrete, the concrete will crack and the unit may fail, with delamination likely.

The reporter makes the following recommendations:

  • Units should be properly supported on delivery vehicles, when stored on site and for temporary support whilst making adjustments

  • The units should have a prepared level store area of adequate size on site

  • End cantilevers should be minimised

  • End cantilevers should not be loaded

  • Follow manufacturer’s instructions for storage and installation.

Expert Panel Comments

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