please check the code attached. I'm trying to design a purlin section on staad pro using various indian codes. in steed design result is800 and is800 2007 WSD failed the section BUT IS800 2007 LSD passed the section. should I consider this section passed or failed. please help me understand.
STAAD SPACE START JOB INFORMATION ENGINEER DATE 03-Apr-19 END JOB INFORMATION INPUT WIDTH 79 UNIT METER KN JOINT COORDINATES 1 0 0 0; 2 3.7 0 0; MEMBER INCIDENCES 1 1 2; DEFINE MATERIAL START ISOTROPIC STEEL E 2.05e+08 POISSON 0.3 DENSITY 76.8195 ALPHA 1.2e-05 DAMP 0.03 TYPE STEEL STRENGTH RY 1.5 RT 1.2 END DEFINE MATERIAL MEMBER PROPERTY INDIAN 1 TABLE ST ISMC75 CONSTANTS MATERIAL STEEL ALL SUPPORTS 1 2 FIXED BUT MY MZ UNIT METER NEWTON LOAD 1 LOADTYPE Dead TITLE DL SELFWEIGHT Y -1 MEMBER LOAD 1 UNI GY -152 LOAD 2 LOADTYPE Dead TITLE LL MEMBER LOAD 1 UNI GY -497 LOAD 3 LOADTYPE Dead TITLE WL MEMBER LOAD 1 UNI GY 1000 LOAD COMB 4 COMBINATION LOAD CASE 4 1 1.0 2 1.0 LOAD COMB 5 COMBINATION LOAD CASE 5 1 0.9 3 1.5 PERFORM ANALYSIS PRINT ALL LOAD LIST 4 5 PARAMETER 1 CODE INDIAN CHECK CODE ALL PARAMETER 2 CODE IS800 LSD CHECK CODE ALL PARAMETER 3 CODE IS800 WSD CHECK CODE ALL FINISH
Dear User,
You have used 3 codes in the file. Every code has some design philosophy and methods. They are different from each other. IS 800 & IS 800 2007 Wsd are based on working stress method. IS 800 2007 LSD is based on limit state method. Now there are differences in design methodology for WSD & LSD. In WSD we work with a stress within elastic limit. In limit state we can go beyond elastic limit. Please refer some standard book to know about this. Also, the load combinations used here is not okay for IS 800 1984 code. So, the results will not be same for all codes and they are passed or failed as per that particular code prohibitions.
thanks for your reply sir, also can u tell me what should be the load combinations in this particular case(for is800 2007 LSD and WSD), and which approach should be preferred( LSD or WSD). what is preferred by the designers for better practicality, safety and economy.