Zalifornia
Student
- Mar 1, 2025
- 1
*Hello All, first time poster, a student who is floored by what a resource this site is. Thanks for the generousity you may give me and every other clueless kid*
In my Building Structural Systems class we are working through the ASCE7-22 and I am hung up on overturning moments and their use in the load combos.
Consider a frame (4 bays, 5 columns, symmetric) with applied lateral loads (see attached).
Per my instructor, to calculate the factored loads in the columns we sum the moments of lateral loads about the frame's base.
Next, assuming the columns rxn's to be proportional to centroidal distance, we "distribute" the moment over the width. Say,
Exterior Column Rxn = OTM÷(bldg. width, 35'×4)
Interior Column Rxn = (Exterior column)×½
These values are then used as Eh or W values in the load combos.
Question: Is this procedure familiar to you? The values are far from accurate.
My instinct would be to use the Portal Method and Cantilever Method (i.e. zero moment at midpoints, etc) which produces good approximate values.
In my Building Structural Systems class we are working through the ASCE7-22 and I am hung up on overturning moments and their use in the load combos.
Consider a frame (4 bays, 5 columns, symmetric) with applied lateral loads (see attached).
Per my instructor, to calculate the factored loads in the columns we sum the moments of lateral loads about the frame's base.
Next, assuming the columns rxn's to be proportional to centroidal distance, we "distribute" the moment over the width. Say,
Exterior Column Rxn = OTM÷(bldg. width, 35'×4)
Interior Column Rxn = (Exterior column)×½
These values are then used as Eh or W values in the load combos.
Question: Is this procedure familiar to you? The values are far from accurate.
My instinct would be to use the Portal Method and Cantilever Method (i.e. zero moment at midpoints, etc) which produces good approximate values.
Attachments
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