LESSON 4 & 5 Flashcards
They are structural elements that are subjected to axial tensile forces. They are used in various types of structures and include truss members, bracing for buildings and bridges, cables in suspended roof systems, and cables in suspension and cable stayed bridges.
Tension Members
Types of Tension Members
- Wires and Cables
- Rods and Bars
- Single Structural Shapes and Plates
- Built-Up Members
Types of Failure
- Yielding Failure
- Rupture Failure
It will happen when the axial stress in the section reaches the yield stress, πΉπ¦. To prevent this, the load must be small enough that the stress on the gross section, π΄π, is less than the yield stress, πΉπ¦.
Yielding Failure / Tension Yielding / Excessive Deformation
It will occur when the steel tears or ruptures. In this situation, the tensile strength or rupture stress, πΉπ’, of the steel is reached. To prevent this, the stress on the net section must be less than the tensile strength, πΉπ’.
Rupture Failure
Formula for Yielding Failure
ππ = πΉπ¦π΄π
πΉπ¦ = π ππππππππ ππππππ’π π¦ππππ π π‘πππ π
π΄π = ππππ π ππeπ
Formula for Rupture Failure
ππ = πΉπ’π΄π
πΉπ’ = π ππππππππ ππππππ’π π‘πππ πππ π π‘πππππ‘β
π΄π = ππππππ‘ππ£π πππ‘ ππππ
π΄π = π β π΄π
π = π βπππ πππ ππππ‘ππ
π΄π = πππ‘ ππππ
It occurs when a βblockβ of the member is βtornβ out. ________________ is characterized by a failure that includes both tension (i.e. normal to the force) and shear (i.e. parallel to the force) failure planes
Block Shear
They are structural elements that are subjected only to axial compressive forces; that is, the loads are applied along a longitudinal axis through the centroid of the member cross section, and the stress can be taken as π = π/π΄, where π is considered to be uniform over the entire cross section.
Compressive Members
Types of Failure in Compressive Members
- Compressive Buckling
- Buckling
- Local Buckling
- Flexural Buckling
- Torsional Buckling
- Flexural-Torsional Buckling
It occurs when some part or parts of the cross section of a column are so thin that they buckle locally in compression before the other modes of buckling can occur. The susceptibility of a column to local buckling is measured by the width-thickness ratios of the parts of its cross section.
Local Buckling
Also called Euler Buckling, members are subject to flexure, or bending, when they become unstable. It is a deflection caused by bending, or flexure, about the axis corresponding to the largest slenderness ratio.
Flexural Buckling
This type if failure is caused by twisting about the longitudinal axis of the member.
Torsional Buckling
It may occur in columns that have certain cross-sectional configuration. These columns by twisting (torsion) or by a combination of torsional and flexural buckling. The member bends and twist simultaneously.
Flexural-Torsional Buckling
It can only occur with double symmetrical cross sections with very slender cross-sectional elements.
Torsional Buckling
