Types of Failures in Steel Structures

The availability, economy, high strength to weight ratio, ductility and elasticity are just a few factors that make steel such a popular building material.  Steel has evolved over the last 100+ years to be a widely used material in structures. However, steel does have several disadvantages that must be taken into consideration when designing a structure.

Types of failure in steel structures are

• Shear failure
• Flexural failure
• Compression failure
• Tensile failure

Shear Failure

Shear failures are occur in connections between members (i.e. Column connection, girder connection, etc.,).  Connections have high shearing forces that an engineer must consider when designing the connection. A failure can occur if the structural engineer underestimates the design force the connection is to withstand. Common connections in steel structures may be made with bolts or welds or a combination of both.

Flexural Failures

Flexural failures occur in flexural members such as members and girders, and, in some cases, compression members such as columns that are subjected to bending stresses.  Flexural members are fail when flexural loadings cause the element to buckle.  Because steel is strong, steel members are designed to be slim and efficient which may put them at risk of buckling. Flexural loadings create tension and compression forces in members. Lateral torsional buckling occurs when the high compression forces causes an unrestrained section of the member to buckle and laterally displace.

Compression Failures

Compression failures typically occur in compression members, such as columns and braces, when the compressive axial force applied to the element caused the element to either buckle or become overstressed. Similar to beams, column and brace members subjected to high compressive stresses may experience buckling.

Tensile Failures

Tensile failures generally occur in brace members or hangers.  This type of failure occurs when the steel member is stretched to a level that exceeds the material strength of the member. Steel is a very strong material and very reliable in structural construction of buildings. Its effectiveness, however, is only guaranteed when the steel is properly designed to withstand the imposed forces. Poor design can lead to the above-mentioned failures of steel structures.