permissible stress การใช้

• Limit state design has replaced the older concept of permissible stress design in most forms of civil engineering.
• The value of the safety factor generally ranges from 0.75 to 0.85 in Permissible stress design.
• Therefore, it is inappropriate to refer to the procedure or philosophy as either Allowable Stress or Permissible Stress Design.
• The bar can be articulated at its extremities and work at its permissible stress, but this requires close end sockets or attachment mechanisms whose volume is far from negligible, especially if the bar is short or highly stressed.
• The permissible stress design approach has generally been replaced internationally by limit state design ( also known as ultimate stress design, or in USA, Load and Resistance Factor Design, LRFD ) as far as structural engineering is considered, except for some isolated cases.
• This situation is magnified when the number of profiles available is restricted, which may explain the use of forms which are not theoretically optimal but which tend to subject the available profiles to the permissible stress " ? " ( such as, for example, pylons for high-voltage electric lines or variable height truss bridges ).