Design of base plate with axial load and bending moment
Design of base plate with axial load and bending moment
(OP)
Hi All,
I am trying to design a base plate with axial load and bending moment. I have different cases of eccentricity: L/6 < e < L/2, L/2 < e < L and e > L.
I found that different references have different methods of designing it:
1) Blodgett uses the assumption of plane section remains plane and solves a cubic equation of forces and strains to get: concrete bearing stress, bearing length and anchor bolt tension.
2) AISC Design Guide 1 says that the above assumption may not be correct as the base plate and concrete may not be in contact everywhere. The anchor bolt tension and concrete bearing stress are independent of each other. The Design guide assumes that the bearing stress will reach max allowable value. The guide then finds the bearing length from summation of moments, and then the anchor bolt tension from summation of forces.
Each of the above methods yield different results. I want your suggestion as to what method is generally used in the industry practices for designing base plate with axial load and bending moment.
Thanks for your time.
I am trying to design a base plate with axial load and bending moment. I have different cases of eccentricity: L/6 < e < L/2, L/2 < e < L and e > L.
I found that different references have different methods of designing it:
1) Blodgett uses the assumption of plane section remains plane and solves a cubic equation of forces and strains to get: concrete bearing stress, bearing length and anchor bolt tension.
2) AISC Design Guide 1 says that the above assumption may not be correct as the base plate and concrete may not be in contact everywhere. The anchor bolt tension and concrete bearing stress are independent of each other. The Design guide assumes that the bearing stress will reach max allowable value. The guide then finds the bearing length from summation of moments, and then the anchor bolt tension from summation of forces.
Each of the above methods yield different results. I want your suggestion as to what method is generally used in the industry practices for designing base plate with axial load and bending moment.
Thanks for your time.






RE: Design of base plate with axial load and bending moment
Timing has a lot to do with the outcome of a rain dance.
RE: Design of base plate with axial load and bending moment
You can get a free base plate program from Hilti called Profis that will do a FE analysis of a plate and bolts but there is little documentation of what it is doing. GTSTRUDL has developed a Base Plate Wizard that creates a FE mesh and boundary conditions that you run in GTStrudl with tons of documentation.
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RE: Design of base plate with axial load and bending moment
Dik
RE: Design of base plate with axial load and bending moment
All of you have essentially used the Blodgett method. But AISC Design guide 1 says:
The plate and the concrete may not be in contact everywhere. So, there is no reason that we can assume plane sections remain plane. Also, the strain diagram may not be linear in the tensile part. So, the strain in the anchor bolt may not be dependent on the concrete strain. So, the anchor bolt force is assumed independent of the concrete stress.
What is you opinion on this.
Thanks for your time.
RE: Design of base plate with axial load and bending moment
RE: Design of base plate with axial load and bending moment
Thanks
RE: Design of base plate with axial load and bending moment
RE: Design of base plate with axial load and bending moment