Structure Lift Analysis using SACS ProgramPosted by SynClaire in Sunday, May 18th 2008   Topics: Civil EngineeringTags: Lift Analysis, Padeye, SACS, Shackle, Sling

1. CREATE STRUCTURE MODEL FOR LIFTING

a) Determine padeye location (4 padeye for commonly use): this padeye’s location usually determining by suitable location on field.b) Determine rigging point location (for dragging structure during lifting), usually use 1 – 2 point of rigging. Because of this rigging will make the structure to move along x or y direction (by dragging use rope or something), so use fixity: 110 000 and/or 100 000 and/or 010 000 (by try and error). Note: after run this SACS you may encounter the warning on message area because of this fixity (by try and error), it’s still acceptable if this warning “MAX iterations below 6”.

 

c) Determine hook point location, this locations determining by searching the CoG (Centre of Gravity) of the structure with some height so that the minimum angle to horizontal would be 60 degrees or more.

d) Determine the Sling Properties, because of this sling would be considering as dummy member we can make the sling as a box and skip the stress analysis (skip using data generator).e) As per API RP2A WSD for those members directly connected to padeyes, a dynamic load factor of 2.0 will be applied, while the factor of 1.35 will be for the remaining member.

LCOMB 1000 = 1.200 DEAD + 1.200 MISCLCOMB 1350 = 1.350 WGHTLCOMB 2000 = 2.000 WGHT

2. CHECK LIFTING STRUCTURE STABILITY

a) Check Point of CoGFind word “RELATIVE TO STRUCTURAL ORIGIN” on SACLST (SACS Output), make sure the Hook Point in the same coordinate as CoG on SACLST (SACS Output).b) Check Reaction Force on Rigging Point Near/Close to ZeroFind word “FIXED JOINTS REACTION FORCES AND MOMENTS” on SACLST (SACS Output)Make sure the reaction on Rigging Point near/close zero, which is Fx, Fy, Fz 0. This reaction near/close zero means the rigging hook can be easily pointing or dragging by human force.c) Check Sling Degree Min 60Make sure the sling angle is more than 60 degree which is as API requirement meet.

3. DESIGN SLING, SHACKLE, PADEYE, AND MAX UC STRESS

Check sling, shackle, and padeye manually as per API requirement.