A computer implemented method for crashworthiness simulation of a car or truck, by initializing bolt pretension independent of axial strain in a finite element analysis for simulating structural responses of a car or truck with bolted joints included therein, the method comprising: defining one or more bolts, each as a beam element in a finite element analysis model of the finite element analysis having a plurality of solution steps in time; defining at least one pretension-versus-time curve for specifying desired pretension of said each of the one or more bolts, wherein the at least one pretension-versus-time curve comprises a ramp portion, a desired pretension portion and an optional unloading portion; conducting a first series of quasi-static analyses at first solution steps covering the ramp portion of the pretension-versus-time curve; conducting a second series of quasi-static analyses at second solution steps covering the desired pretension portion of the pretension-versus-time curve, at each of said second solution steps, incrementing current time in the finite element analysis by a time step, dt, identifying a group of bolts to be excluded by detecting and determining which one of the one or more bolts are to become unloaded and performing one of said second series of quasi-static analyses without the group of bolts to be excluded until the current time exceeds the desired pretension portion's end time; and achieving of the initializing bolt pretension by terminating the second series of quasi-static analyses when either of first and second bolt pretension termination conditions has been detected and determined, wherein the first bolt pretension initialization termination condition comprises global structural energy equilibrium and wherein the second bolt pretension initialization termination condition comprises that all of said one or more bolts have been detected and determined to become unloaded. defining one or more bolts, each as a beam element in a finite element analysis model of the finite element analysis having a plurality of solution steps in time; defining at least one pretension-versus-time curve for specifying desired pretension of said each of the one or more bolts, wherein the at least one pretension-versus-time curve comprises a ramp portion, a desired pretension portion and an optional unloading portion; conducting a first series of quasi-static analyses at first solution steps covering the ramp portion of the pretension-versus-time curve; conducting a second series of quasi-static analyses at second solution steps covering the desired pretension portion of the pretension-versus-time curve, at each of said second solution steps, incrementing current time in the finite element analysis by a time step, dt, identifying a group of bolts to be excluded by detecting and determining which one of the one or more bolts are to become unloaded and performing one of said second series of quasi-static analyses without the group of bolts to be excluded until the current time exceeds the desired pretension portion's end time; and achieving of the initializing bolt pretension by terminating the second series of quasi-static analyses when either of first and second bolt pretension termination conditions has been detected and determined, wherein the first bolt pretension initialization termination condition comprises global structural energy equilibrium and wherein the second bolt pretension initialization termination condition comprises that all of said one or more bolts have been detected and determined to become unloaded.