Reasons for collapsing of foundation

There are several reasons for collapsing of foundation which range from poor soil condition, structural faults etc. Given below, some of the major causes for collapsing of foundation :-

1. Collapsing of Foundation because of surpassing the bearing strength of soil
2. Collapsing of Foundation because of withdrawn of moisture from Soil all of a sudden
3. Collapsing of Foundation because of differential or unequal settlement
4. Collapsing of Foundation because of uneven progress and pattern of construction
5. Collapsing of Foundation because of movement of adjacent soil.

Collapsing of Foundation because of surpassing the bearing strength of soil:-

Ultimate bearing strength means ultimate load intensity that a soil can bear devoid of any shear failure of the Soil. The size of the footing with regard to length, breadth and diameter, is primarily based on the bearing strength.

A foundation/ footing of a structure must contain adequate size in order that the intensity of load directing via that footing from the structure to the soil below should not raise the bearing strength of that soil. If the bearing strength of soil is low or load operating is heavy and the size of the footing is relatively small than actual requirement then the load intensity (i.e. load per unit area say KN/sq.m. etc.) conveyed on the soil may be greater as compared to the bearing strength of the soil, for this reason a shear failure of soil will occur.

To provide perfect footing size, the safe bearing strength rather than ultimate bearing strength should be applied to obtain margin of safety against any accidental loading as well as abnormal behavior of the soil due divergence in its bearing strength. Safe bearing strength is nothing but ultimate bearing strength divided by a appropriate factor of safety usually varying from 2 to 4.

Collapsing of Foundation because of withdrawn of moisture from Soil all of a sudden :

It is one of the most crucial factors that should not be neglected. Moisture withdrawn occurs in the following ways :-

a) By draining water from the adjacent well through pump
b) By dewatering adjacent Pond
c) Reduction of ground water table close to the ground previously.

Since the soil usually comprises of soil solid, water and air and super structural load on soil is carried by the both soil solid and pore water, as soon as the pore water is withdrawn, it will produce voids inside the soil system around and at the bottom of the foundation soil that leads to subsidence of the soil together with supporting structure. As a result, the collapsing of foundation happens.

To get more details about other reasons for failure, go through the following link www.mycivil.engineer



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Published By
Rajib Dey
www.constructioncost.co
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Brief explanation of welded connection of single angle section with gusset connection

In this construction video tutorial, one can learn how to follow IS 800-2007 limit state method for developing the welded connection of the single angle section that contains gusset connection.

You will learn what exactly a welded connection is in tension members. When two members in a structure are associated using the welds, such a connection is defined as welded connection.

The elementary types of welded connections are categorized on the basis of the types of welds, position of welds and type of joint.

Depending on the type of weld, welds are categorized into fillet weld, groove weld (or butt weld), plug weld, slot weld, spot weld etc.

Welding facilitates transmission of stress directly among members removing gusset and splice plates which are essential for bolted structures. Therefore, the weight of the joint is lowest. Toward tension members, the nonexistence of holes enhances the effectiveness of the section. It includes fewer fabrication cost with regard to other methods because of execution of fewer parts and removal of operations like drilling, punching etc. and subsequently fewer labor resulting in cost reduction.

Single-angle compression members belong to simple structural components. It is very complicated to make analysis and design of these members. These members are generally associated with other members through one leg only. Therefore, the load is employed eccentrically.

A gusset plate is made of a thick sheet of steel used for linking various structural steel elements like beams and girders to columns as well as uniting truss members. The gusset plate is set up at the juncture of two or more adjoining beams, chords, or columns. It is tied to each steel framing member with bolts, rivets or welding or an amalgamation of the three. The objective of the gusset plates is to connect the steel together as well as provide strength and support to each joint. These are mostly found in bridges and buildings as well as other structures.

Watch the online demonstration.

Read more

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Published By
Rajib Dey
www.constructioncost.co

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