| Structural Comments |
| Every building has, in addition to supporting the weight of the structure and the loads imposed upon it from it's use (vertical loads), to resist the sideways forces imposed upon it by the wind and by notional horizontal forces which must be considered in the design (lateral forces). In general this can be achieved by one or a combination of the following methods. Each of these methods relies on the presence or use of a suitably rigid roof construction to form a "rigid plate" that is able to transmit the lateral forces to the vertical elements that are designed to resist them, |
| 1) Fixed Base Method |
| Resistance to lateral forces is achieved by designing some or all of the columns as vertical cantilevers. To achieve this the foundations, columns and the base plates to the columns are designed, not only for the vertical loads but for the moments induced by the lateral forces. |
| 2) Pinned Base / Portalised Frame Method |
| This method assumes no resistance at the base other than simple lateral shear, the connections between the columns and the beams are designed to resist the moments induced by the lateral forces. This results in smaller foundations than the fixed base method but more substantial column to beam connections. |
| 3) Braced Frame/Shear Wall Method |
| This method uses either crossed tie bracing, inclined strut bracing or the use of fairly substantial lumps of structure i.e. brick or concrete walls within the building to resist the lateral forces. When considering an existing building it is impossible, without project specific details or substantial on-site investigations, to confidently determine how the overall lateral stability of any particular building was achieved. The safe approach is therefore to ensure by specific design that each panel of cladding removed is replaced by a panel whose material and perimeter fixings provide at least as much lateral resistance as the original panel achieved when first constructed. Whilst this may sound onerous, in regard to a relatively simple form of structure such as the 2M Oxford Method and with the use of brickwork replacement cladding this is likely to be achieved by the details required to ensure individual panel wind stability, which in turn depends on the specific layout of elevation i.e. overall panel size, proportions, number and size of openings and their location within the panel. |
©2004 Oxford Method Royalties Management Group