Pages de Calcul de Coffrage6
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7.2.2 Horiz ont al Loa ds Braces sho uld be des ign ed to res ist all for ese eab le hor izo nta l loads, such as seismic forces, wind, cable tension, inclined sup- ports, dumping of concrete, etc. Wall form bracing must be designed to meet the minimum wind load requirements of ANSI A58.1 or the local design building code , whiche ver is more stri ngent . For exp osed wal l, the minimum wind design load should not be less than 15 psf. Bracing for wall forms should be designed for a horizontal load of at least 100 lb per lineal foot of the wall, applied at the top. 7.3 METHOD OF ANALYSIS Step 1: The proc edure for app lying eq uations of Tables 3.15 and 3.16 to the design of a sheathing is to consider a strip of 1 ft depth (consider the lower 1 ft of sheath- ing where concrete lateral pressure is maximum). Determine the maximum allowable span based on the allowable values of bending stress, shear stress, and deflection. The lowest value will determine the maximum spacing of studs. Step 2: Base d on the selected stu d spaci ng, the stud itsel f is ana lyz ed to det ermine its max imu m all owa ble spacing. The studs are subject to uniform pressure resulting from the fresh concrete. This pressure is resisted first by the sheathing which in turn transfer the loads to studs. The selected stud span will be the spacing of the wales. Step 3: Base d on the selected stud spa cing , the maximum wale spacing (distance between horizontal supports or ties) can be determined using the same proce- dur e. For simpl ici ty and eco nomy of des ign , thi s maximum span va lue is usually rounded dow n to the next lower integer or modular value when selecting the spacing.
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Transcript of Pages de Calcul de Coffrage6
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Wall Form Design 191
7.2.2 Horizontal Loads
Braces should be designed to resist all foreseeable horizontalloads, such as seismic forces, wind, cable tension, inclined sup-ports, dumping of concrete, etc.
Wall form bracing must be designed to meet the minimumwind load requirements of ANSI A58.1 or the local design buildingcode, whichever is more stringent. For exposed wall, the minimumwind design load should not be less than 15 psf. Bracing for wallforms should be designed for a horizontal load of at least 100 lbper lineal foot of the wall, applied at the top.
7.3 METHOD OF ANALYSIS
Step 1: The procedure for applying equations of Tables 3.15and 3.16 to the design of a sheathing is to considera strip of 1 ft depth (consider the lower 1 ft of sheath-ing where concrete lateral pressure is maximum).Determine the maximum allowable span based onthe allowable values of bending stress, shear stress,and deection. The lowest value will determine themaximum spacing of studs.
Step 2: Based on the selected stud spacing, the stud itselfis analyzed to determine its maximum allowablespacing. The studs are subject to uniform pressureresulting from the fresh concrete. This pressure isresisted rst by the sheathing which in turn transferthe loads to studs. The selected stud span will bethe spacing of the wales.
Step 3: Based on the selected stud spacing, the maximumwale spacing (distance between horizontal supportsor ties) can be determined using the same proce-dure. For simplicity and economy of design, thismaximum span value is usually rounded down to thenext lower integer or modular value when selectingthe spacing.
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