Can I specify different values of stiffness for compression and tension at the same support for example 1200 K/in in compression but 800 K/in in tension ?
Yes. You may use the multilinear springs which allows one to specify different spring stiffness values corresponding to the support displacements. So one can specify the value for spring stiffness as 1200 K/in for all negative displacements ( support in compression ) and specify spring stiffness as 800 K/in for all positive displacements ( support in tension ). For details on how to specify multilinear springs, please refer to section
Technical Reference of STAAD Commands > TR.27 Support Specifications > TR.27.4 Multilinear Spring Support Specification in the STAAD Help manual in CONNECT Edition. In older V8i version refer section 5.27.4 of the technical reference manual, titled Multilinear Spring Support Specification.