AISC ASD code refers to Allowable Stress Design, AISC LRFD is Load and Resistance factor Design and AISC 360-05 refers to the Unified code or it is a single design code which follows the same design equations but the final design strength is determined by multiplying and diving the nominal strength by some coefficient respectively. For AISC-ASD code, the the Design strength is determined by diving the Nominal strength by 1.67, whereas in case of AISC -LRFD code, the design strength is determined by multiplying with the resistance factor of 0.9...Now, regarding your second part of query, just wondering if you have used the AISC LRFD Load Combination in your second model. If not, then it is very obvious that the design strength determined in case of AISC-ASD will be lesser than that of AISC LRFD as you are scaling down the nominal strength by 1.67 in the former situation and scaling down the Nominal strength by (1/0.9=1.11) in the latter one, which means AISC-ASD model has lesser design strength of a selected member than that of the AISC-LRFD model and hence the structure is failing in the first model.
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