Sliding Resistance

[dherna45]

Hello guys. I am working on seismic retrofit of a soft story and using a steel moment frame as the solution. I am designing the foundation using a grade beam and pad footing at the support. I am trying to find the sliding resistance of the foundation and compare it to the base shear. I have found that the sliding resistance is equal to F+Hp-Ha
F= Frictional Resistance (I know it is the weight x coefficient of friction)
Hp= passive resistance due to horizontal movement
Ha= active pressure due to horizontal movement of the foundation
How do I calculate Hp and Ha. Thanks for your help

 

[MotorCity]

Take a look in any foundation design book and become familiar with the pressure diagrams, it is fairly straight forward. Also, the active pressure does not contribute to the sliding resistance as you state above, it is causing the sliding.

 

[dherna45]

I was told that I am supposed to find the passive resistance for all the surfaces of the grade beam, add them up to the weight of the beam times the tan(angle of friction)

 

[wannabeSE]

I typically rely on a soils report for this information. However, the 2015 IBC section 1806 has some presumptive values for lateral resistance.

 

[Okiryu]

Google "Rankine earth pressure". For example, This link is for Wikipedia:

https://en.m.wikipedia.org/wiki/Lateral_earth_pressure