What is Structural Design?

It is a method or tool by which we find out safe and economical specifications of a structure or a member of the structure sufficient to carry the load.

In other words finding out cross-sectional dimension, grade of material, amount of reinforcement etc. necessary to withstand the internal forces that we have got from structural analysis.

What is Structural Analysis?

It is a method or tool by which we find out how a structure or a member of a structure behaves when subjected to certain excitation.

In other words finding out internal forces (axial force, shear force, moment), stress, strain, deflection etc in a structure under applied load conditions.

What is Structural Engineering?

It is a field of engineering dealing with the analysis and design of structures that support or resist loads.

Structural engineering theory is based upon physical laws and empirical knowledge of the structural performance of different materials and geometries. Structural engineering design utilizes a number of simple structural elements to build complex structural systems.

Structural engineering depends upon a detailed knowledge of applied mechanics, materials science and applied mathematics to understand and predict how structures support and resist self-weight and imposed loads. To apply the knowledge successfully a Structural engineering generally requires detailed knowledge of relevant empirical and theoretical design codes, the techniques of structural analysis, as well as some knowledge of the corrosion resistance of the materials and structures, especially when those structures are exposed to the external environment. Since the 1990s, specialist software has become available to aid in the design of structures, with the functionality to assist in the drawing, analyzing and designing of structures with maximum precision; examples include AutoCAD, StaadPro, ETABS, Prokon, Revit Structure etc. Such software may also take into consideration environmental loads, such as from earthquakes and winds.

What is Live Load?

Refers to loads that do, or can, change over time, such as people walking around a building (occupancy) or movable objects such as furniture.

Live loads are variable as they depend on usage and capacity. However, design codes can provide equivalent loads for various structures.

Loads prescribed by codes are empirical and conservative based on experience and accepted practice.

What is Dead Load?

Deal load refers to loads that relatively don’t change over time, such as the weight of

All permanent components of a building including walls, Beam, columns, flooring material etc)

Fixed permanent equipment and fitting that are an integral part of the structure.(like plumbing, HVAC, etc.)

The dead loads are calculated from the member sizes and estimated material densities.

What is Bearing Capacity of Soil?

All civil engineering structures whether they are buildings, dams, bridges etc. are built on soils. A foundation is required to transmit the load of the structure on a large area of soil. The foundation of the structure should be so designed that the soil below does not fail in shear nor there is the excessive settlement of the structure. The conventional method of foundation design is based on the concept of bearing capacity.

Soil when stressed due to loading, tend to deform. The resistance to deformation of the soil depends upon factors like water content, bulk density, angle of internal friction and the manner in which load is applied on the soil. The maximum load per unit area which the soil or rock can carry without yielding or displacement is termed as the bearing capacity of soils.

Soil properties like shear strength, density, permeability etc., affect the bearing capacity of soil. Dense sand will have more bearing capacity than loose sand as unit weight of dense sand is more than loose sand.

If the bearing capacity of soil at shallow depth is sufficient to safely take the load of the structure, a shallow foundation is provided. Isolated footing, combined footing or strip footing are the option for the shallow foundation. Deep foundations are provided when soil immediately below the structure does not have the adequate bearing capacity. Pile, piers or well are the options for deep foundations. Mat or raft foundations are useful for soil which is subjected to differential settlement or where there is a wide variation in loading between adjacent columns.

Methods of determining bearing capacity

The various methods of computing the bearing capacity can be listed as follows:

Presumptive Analysis

Analytical Methods

Plate Bearing Test

Penetration Test

Modern Testing Methods

Centrifuge Test

What are Shear Walls?

Shear wall is a structural member used to resist lateral forces i.e. parallel to the plane of the wall. For slender walls where the bending deformation is more, Shear wall resists the loads due to Cantilever Action. In other words, Shear walls are vertical elements of the horizontal force resisting system.

In building construction, a rigid vertical diaphragm capable of transferring lateral forces from exterior walls, floors, and roofs to the ground foundation in a direction parallel to their planes. Examples are the reinforced-concrete wall. Lateral forces caused by wind, earthquake, and uneven settlement loads, in addition to the weight of structure and occupants, create powerful twisting (torsional) forces. This leads to the failure of the structures by shear.

Shear walls are especially important in high-rise buildings subject to lateral wind and seismic forces. Generally, shear walls are either plane or flanged in section, while core walls consist of channel sections. They also provide adequate strength and stiffness to control lateral displacements.

The shape and plan position of the shear wall influences the behaviour of the structure considerably. Structurally, the best position for the shear walls is in the centre of each half of the building. This is rarely practical, since it also utilises the space a lot, so they are positioned at the ends. It is better to use walls with no openings in them. So, usually, the walls around lift shafts and stairwells are used. Also, walls on the sides of buildings that have no windows can be used.

What is Pre-Stressed Concrete?

Pre-stressing is generally a way to overcome concrete weakness in tension. Generally, the concrete undergoes compression on top flange and tension at bottom flange. In pre-stressing the tendons are stretched along the axis and cement is poured, later when the tendons are released the compression is generated at the bottom which tries to counter-balance the compression due to loading at the top part of the beam. The upward force along the length of the beam counteracts the service loads applied to the member. The unique characteristics of pre-stressed concrete allow predetermined, engineering stresses to be placed in members to counteract stresses that occur when the unit is subjected to service loads.

Pre-stressing removes a number of design limitations conventional concrete faces on span and load and also permits the building of roofs, floors, bridges, and walls with longer unsupported spans. This allows architects and engineers to design and build lighter and shallower concrete structures without sacrificing strength. This also helps in the construction of longer spans thereby reducing the intermediate pier construction and making bridge construction economical.

Pre-stressed concrete has experienced the greatest growth in the field of commercial buildings. For buildings such as shopping centers, pre-stressed concrete is an ideal choice because it provides the span length necessary for flexibility and alteration of the internal structure. Pre-stressed concrete is also used in school auditoriums, gymnasiums, and cafeterias because of its acoustical properties and its ability to provide long, open spaces. One of the most widespread uses of pre-stressed concrete is parking garages.