A windpost is a structural item used in the design and construction of masonry walls to increase lateral wall stability and protect them against damage from horizontal forces imposed by wind pressure, crowd or handrail loads
Large panels of masonry or panels with openings can often be difficult to justify structurally. The traditional solutions have been to either increase the thickness of the wall or introduce an additional column. Ancon Windposts fit within the wall allowing the existing thickness to be maintained.
Ancon WP1 and WP3 Windposts
Ancon WP1 and WP3 Windposts are channel section windposts which are designed to be installed within the cavity leaving the blockwork undisturbed. The windposts are complete with end connections and ties which fit into the vertical slots in the flanges of the channel section.
Ancon WP2 Windposts
Ancon WP2 Windposts are angle section windposts designed for either small cavities or where wind loads are high. One leg of the angle windpost is built into the blockwork, and the blockwork tied through the leg of the windpost to minimise any possible movement or cracking of internal finishes. If a vertical movement joint is required in place of a tied joint, ties with a plain end on one side can be supplied.
Ancon WP4 Windposts
Ancon WP4 Windposts are generally used in internal blockwork walls that have a ‘fair faced’ finish to both sides and where the windposts cannot protrude beyond either face. Sometimes referred to as ‘spine’ posts they are flat plates designed to fit within the wall. Although the depth of a WP4 post is limited by the width of the masonry (ideally 20mm less than the wall width) the thickness of the post can vary to increase its load capacity. Blockwork is tied through the post. Debonded ties can be used if the post is positioned at a movement joint.
Ancon Windposts are designed to span vertically between floors to provide lateral support for panels of brickwork. The windposts will usually be restrained by the brickwork and designed as ‘simply supported beams’.
Deflection under wind load will often limit the maximum loading. Windposts can be designed as ‘propped cantilevers’ to limit deflection, this however will require a much larger base connection which in many cases may be difficult to accommodate.
Connections to the frame are designed to permit adjustment during installation. Serrated surfaces will be provided where adjustment is in the direction of the load. The top connection allows for shrinkage or vertical movement of the frame to take place. The type of fixing will depend on the nature of the frame. Expansion bolts are normally supplied for concrete frames and set screws will be supplied for steel frames.
Ancon Parapet Posts are restrained by the brickwork and designed as ‘cantilevers’. The base connection will need to be sufficient to resist the ‘bending moment’ and may in some cases be difficult to accommodate within the floor construction. The height of these posts is unlikely to be more than 1.6 metres.
Fixings for Windposts and Parapet Posts
Connections to the frame can be made in a variety of ways and will depend on the type of post, structure and fixing being used.
The choice of fixing and its position is dependant on the type and length of the windpost and the structure to which it is being fixed. Ancon designs fixing details for the top and base of each windpost and a drawing is issued for approval prior to manufacture.
The bolt in the slotted connection at the top of the windpost is positioned so that vertical movement of the frame can take place.