Is tension in footing due to the overturning moments not allowed? because as the ratio of Ov.Moment/section Modulus is exceeding Axial Load/Area of footing , the value for P/A-M/Z is negative , if this negative which means tension is developed in the footing , so can we allow tension in the footing? please note that i cannot increase the area of footing (because of other reasons) to eliminate the Tension? so what is the other solution to this problem?please also explain if i can proceed with tension in footing?
Answer Dear Arsalan
In the case of a single footing , overturning may cause damage but in a footing network of a structure overturning may cause a redistribution of loadings and moments and excess displacement. Negative stress or tension is not allowed in footing but this is not the final judgement because when a section cant resist the tension it redistribute the loading so that there is no tension in the section , then usually the effective width of the footing decrease to diminish the moment applied on the footing. In a extreme case the the effective footing reduce to a point and a local failure due to stress concentration occur underneath of the related column. Then you have to perform a try and error process to find the final state of the base stresses with no tension. Then your essential responsibilty is to judge wether you can accept the excess stress due to tension removing from the model or not.
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