Realistically assessing load severity on concrete foundations and mountingsystems for large reciprocating compressors

This paper addresses the loads generated and transmitted by large reciproca ting compressors to their concrete foundations. It emphasizes the need to q uantify (realistically) the loads that must be transmitted across the tie-d owns connecting a compressor to its foundation, and it identifies the signi ficance of these loads to the integrity of tie-downs and concrete. It consi ders gas forces induced by the compression process, unbalanced inertia forc es induced by reciprocating and rotating motion of compressor components, a nd shows the importance of considering forces from individual throws and cy linders. The paper documents the assumptions regarding compressor frame fle xibility strongly influence predictions of tie-down forces, and that the mo st common assumption (zero flexibility) can grossly underestimate these for ces. The alternative assumption of a fully flexible frame provides conserva tive (high) force values. finite element analysis of the combined compresso r frame and concrete foundation system provides the most accurate load valu es but requires a significant increase in computational complexity. The pap er quantitatively compares these alternative assumptions, provides a basis for making a choice, and shows how predicted loads influence tie-down desig n parameters and concrete stresses.