Analysis of typical pallet racks under seismic conditions

The present graduation thesis deals with two different steel pallet racks Trimo VRS 2 and Trimo VRS 3. Pallet racks are not typical structures, as their variable load presents the most significant part of the gravity load. During an earthquake that variable load proves to have an advantageous influence on the racks' seismic load. We considered this with various factors. These factors are defined in the recommendations of pr FEM 10.2.08. A modal response spectrum analysis and a non-linear time history analysis were performed for both racks. We used the computer programme SAP 2000 and found out that SAP2000 is not exactly good for time history analysis, because of problems with convergence. The VRS 3 rack was modelled as a spatial model and the VRS 2 rack, due to its symmetry, as a planar model. We made use of seven different earthquake records, and standardized them at the peak ground acceleration. The tension diagonals were modelled as non-linear plastic springs. We used Takeda modes as a hysteretic loop with zero compression strength. We also tested the influence of the reduced section of the tension diagonals on internal forces and displacements. Both racks already exist, which is the reason why we only made checkings of sections, stability and displacements. Results of time history analysis are less advantageous than results of modal analysis. Time history analysis with reduced section of tension diagonals contribute smaller internal forces but bigger displacements than constant sections of tension diagonals.