Black Box

Calculations   >   Masonry   >   Masonry Bearing Wall Design

Masonry Bearing Wall Design

The scope of this calculation module is to check the bearing stress for loads acting on the masonry wall. The wall type can be either solid or cavity with or without grout. The bearing stress of the component is computed taking into consideration the specified masonry properties and categories. Spreader beam or pad stone can be provided in order to increase the bearing area and to reduce the stress below.

Standards: British.

Features

  • The design module allows the user to capture the actual site / design requirements via various options such as,
  • Masonry properties
  • Masonry constructions
  • With or without piers
  • With or without spreaders
  • Beam spanning direction
  • In order to better use of the module, selection based material properties are given such as,
  • Type of bricks used and their properties
  • Clay and calcium silicate bricks
  • Autoclaved aerated concrete blocks
  • Aggregate concrete blocks (of various porosity)
  • Solid aggregate concrete blocks laid flat
  • Solid aggregate concrete blocks collar jointed
  • Masonry unit category (as defined in code provision)
  • Construction control category (as defined in code provision)
  • Wall type
  • Solid
  • Cavity non-grouted
  • Cavity grouted

Design Considerations

  • The ratio of masonry unit height to least horizontal dimension of masonry unit and the ratio of masonry unit height to effective thickness of masonry wall has been limited to a definite range for different wall types.
  • The stress concentration which occur underneath the beam or spreader disperses throughout the masonry and it is assumed that the dispersal occurs at an angle of 45°.
  • The distribution of stress under the spreader beam is derived from an acceptable elastic theory, either simple elastic theory assuming a triangular stress block with zero tension or 'Timoshenko’s analysis for elastic foundations'.
  • The beam that imparts load to the masonry wall underneath is assumed to be relatively stiff, thus the allowable bearing stress is enhanced to 25%, 50% and 100% based on the beam to masonry wall interaction area.
  • Based on beam spanning direction the beam may be considered as in-plane or out plane.
  • The calculation of design bearing stress is based on the position of beam placed on spreader beam, i.e. load acting at midpoint of spreader, load acting at middle third of the spreader and load acting outside the middle third of the spreader.
  • The design bearing stress and allowable bearing stress at 0.4 * h (height of masonry wall) underneath the beam bearing level is checked.

National Standards Available

British Standard

References

  • British standard: BS 5628-1:2005 Code of practise for the use of masonry.
  • “Design of structural elements” - W.M.C.McKenzie.

Revision

  • Ver 1.0 - Original version