Structural Analysis - Important Concepts

Structure is defined as a system of interconnected members assembled in a stable configuration and used to support a load or combination of loads. We can classify the Structures in many ways. Based on the type; solid, frame, shell, membrane, composite etc. Based on usage; building, bridge, dam, tunnel, retaining wall, railway, road, canals, aqueduct, chimney, offshore plateforms etc. Based on material; timber, steel, concrete, composite, masonry etc. A structure can be one-dimensional (beam, column, cable etc.), two-dimensional (membrane, plate, shell, slab, dome etc.) or a thhree-dimensional solid mass. A structure can be called as low-rise, high-rise, multi-storied, supertall, skyscraper etc.

The load acting on the structure can have vertical or lateral effects on the structural components. The loads acting on the structures can be divided into following categories:

D – Dead loads; L – Live loads; F – Fluid loads: W – Wind loads;
S – Snow loads; E – Earthquake loads; T - Thermal Loads
H – Earth pressure loads;

The structural members are connected together by providing different types of joints or supports. Most common types of supports are pin-jointed or hinged, roller support and fixed support. Every support provide some restraint (reaction) to the structural members connected to it. A pin-jointed support will develop two reactions on the connected member because it does not allow it to translate in any direction (along x and y) whereas the roller support can provide the reaction only in the direction other than movement of roller i.e, perpendicular to the surface on which the rollers are kept. A fixed support provide restraint to translation as well as rotation, therefore it has 3 reactions (2 forces and one moment). 

Structural Analysis is the branch which involves in the determination of behaviour of structures such as Buildings, Bridges, Dams, Towers, Offshore Platforms, Retaining Walls,  Truss, Foundations and Stadiums. The concepts of Statics provide basis for solutions to the structures. Computer software are also being used for the calculation of forces, bending moment,  stress, strain and deformation or deflection for complex structural systems. Sophisticated equipments are also used for investigating the structural response under different types of loading. Basic concepts of applied mechanics are essential before structural analysis. Structural analysis provides the basis for Structural Design.

A structure can be statically determinate or indeterminate.

Statically determinate structures

A structure is termed as statically determinate if all of its unknown forces can be determined by using only the equations of static equilibrium. For example cantilever, simply supported beam etc.

Learn more by watching our Video Lectures on different topics of structural analysis and design

What is statically indeterminate structure