The most significant expectation for ages has been building structures which are as high as possible, without column and wide-spanned in architecture. Also it is vital to cover these structures as spatial trusses. Similarly; economic, rapid, safe and aesthetical solutions in space systems are possible by spatial steel structures. In last decades, ATC 40, FEMA 273, 274, 356 and recently 440 are the most commonly used resources for seismic analysis procedures enduring with computing in civil engineering. These procedures are defined as displacement based performance analysis. On the other hand, nonlinear static procedures as basic step of these methodologies still have some problems in theoretical background. Some of the researchers are not satisfied with the accuracy of current performance based design methodologies. There are some question marks on how accurate capacity and demand spectrums demonstrate the structural capacity and earthquake demand respectively. In this study, comparison of improved nonlinear static procedures in FEMA- 440 has been made for spatial steel trusses supported on steel columns. For this, numerical models which are set up by taking structural properties of evaluable structures are investigated by using improved nonlinear static procedures which are given in FEMA- 440. Differences and harmonies of methods are still been determined.