Foundation design for high rise building
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Date
2013
Authors
Faisal Mohammad Hassouna
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Abstract
Foundation is the part of structure, which usually placed below the surface of the ground ( sub structure ) and transmit the load to underling soil or rock . all soil compress noticeably when loaded causing the supported structure to settle . the main function of foundation to the ground without causing soil failure or unsafe differential settlement of the supported structure .Design of foundation involves a soil study to establish the most suitable type of foundation and structural design to determine the proportions of the foundation elements.Foundation engineering can be defined as the science and art of applying the principles of soil and structural mechanism together with engineering judgment to solve the inter facing problem.Purpose of foundation:The foundation is a special, important, artificially built constituent part of a structure having its purpose.To receive and transmit structure loads and loads externally applied to the super structure (wind, vibration) to the soil or rock at a given depth below the ground surface which ever is the case.To distribute stress at the base of footing of the foundation to an intensity allowable on the soil or rock .Our work in this project consists of the following:- Study the geotechnical conditions of the site through the soil.- Investigation report prepared for the building under consideration.- Make detailed calculation of loads coming down from the superstructure.- Design two types of foundations.- Compare the two foundations after natives by making analysis of cost for the implementation of each of the alternatives.- Give the recommendation.( 2.1 ) General Requirements of foundationA foundation must be capable satisfying stability and deformation requirements such as:1) Depth must be adequate to avoid lateral explusion of material from beneath the foundation particularly for footings and mats.72) Depth must be below the zone of seasonal volume changes by freezing, thawing, and plant growth.3) System must be safe against over turning, rotation, sliding, or soil rupture (shear-strength failure).4) System must be safe against corrosion or deterioration due harmful material present in the soil. this is a particular concern in reclaiming sanitary land fills and sometimes for marine foundations5) System should be adequate to sustain some changes in later site or construction geometry, and be easily modified should later changes be major is scope.6) The foundation should be economical in terms of the method of installation.7) Total earth movement (generally settlement) and differential movement should be tolerable for both the foundation and super structure element.8) The foundation and its construction, must meet environmental protection standard.Foundation classifications:The type of footing for a particular structure is influence by many factors that may control type of foundation to be used these main factors are :- the strength and compressibility of various soil structure at the site.- The magnitude of the column loads.- The position of water table and the depth of foundation of adjacent buildings .In short we can classify the foundation into many types as following:1) Shallow foundation: its depth is generally (DB), it contains isolated, combined, strap, and raft foundation.2) Deep foundations: with D> (4 or 5) * B, pile foundation is one type of deep.3) Special foundation.Section of type of foundation:If the layer of soil of foundation level suitable for bearing the loads is located at relatively shallow depth, the structure may be supported by shallow foundation. If the upper strata are too weak or compressible, the loads are transferred to more suitable soil layer at greater depth by means of deep foundation.