Investigation of Balanced Non-linear Behavior of Tie Foundations in Comparison with the Regulations of Iran and NEHRP

Ties are designed and executed in order to prevent foundation mutual movements. According to the regulations of Iran and NEHRP, ties are designed for 10 and 25 percent of the greatest axial force (tensile and pressure) in either columns of two ends of ties, respectively. The question arising here is that how can ties be designed according to Iran and NEHRP regulation for a percentage of maximum axial loads of surrounding columns. To what stage of loading is their function effective to prevent relative settlement? When will plastic joints be formed? And finally for which forces should tie be designed in order to prevent formation of plastic joints? In this research 8 individual footings models together with linking tie were analyzed under nonlinear analysis in ANSYS software. For a better perception of effective parameters in tie designing, the changes of axial forces maximally between two columns (column bases) to the force of tie designing as well as relative settlement of tie were investigated in the following three conditions: 1-Studying horizontal distance of two Individual footings. 2- Studying the effect of type of soil in analysis of individual footing. 3- Studying the effect of gravity load in analysis of individual footing. It is obvious that by analysis of finite element models and studying their relative settlement we can evaluate the function of tie and answer the issues raised to some extent.