Document Ew1JmaYBZdaMg5Kxb12JxYjL

17--Building Construction and Maintenance Fic 17-2 --Wall bracing must be adequate for anticipated wind loads This shows the result of not sup plying bracing for a partially constructed wall Lateral bracing Incomplete buildings for which designed lateral support is not yet in place, and all free standing walls should be adequately braced against the maximum anticipated wind pres sures Extenor masonry walls, especially of either load-beanng or nonload-beanng type what ever their height, are subject to wind loads be yond their designed capacity pnor to the final set of the mortar or final be into the structure These wind loads have caused walls or secbons of walls to break off and fall, causing both personal injury (somebmes fatal) and property damage See Figure 17-2 Masonry walls should follow the erection of permanently installed structural members so that adequate lateral stability is provided If this is impossible or impractical, temporary bracing should be placed until structural mem bers can be installed Usually the architect will include in his de sign pilasters as well as the requirements for anchors and ties Also local building codes 406 require that during erecbon of walls the proper bracing and supporting shall be pro vided The quesbon is, what is proper During construction of exterior masonry, two external forces should be considered--the weight (vertical) and the wind load (hori zontal) Because the vertical load is sup ported by spandrels and relieving angles, the cnbcal considerabon is the horizontal load Protecbon or bracing for this load must be pro vided either by screening or by simple shoring Codes and other engineering data indicate the thickness and height of walls which will withstand specific wind loads while unsup ported These specifications should be checked against the local wind conditions and bracing provided when required (See R W Armstrong citabon m "References ") The Nabonal Building Code (1967 Edibon) requires the following During erection, masonry walls shall not be built higher than 10 times their thickness unless adequately braced or unbl provision is made for the prompt installation of permanent bracing at