Elements

Herein some settings related to the analysis of frame elements can be defined.

Carry out Stress Recovery
Some beam element formulations, such as those currently employed in SeismoBuild for the inelastic frame elements, feature the disadvantage that, if the nodal displacement is zero, one then gets also nil strains, stresses, and internal forces (e.g. if one models a fully-clamped beam with a single element, and applies a distributed load, the end moments will come out as zero, which is clearly wrong). To overcome this limitation, it is common for Finite Element programs to use so-called stress-recovery algorithms, which allow one to retrieve the correct internal forces of an element subjected to distributed loading even if its nodes do not displace. It is noted, however, that (i) such algorithms do not cater for the retrieval of the correct values of strains and stresses, given that these are characterised by a nonlinear history response, and (ii) will slow down considerably the analyses of large models.

Do not consider the axial force contribution in the shear capacity of beams
By activating this option the ability to carry out shear checks ignoring the actual axial force applied on the beam member is provided. This feature is particularly important to the shear capacity checks of beams, when the interaction between fibre modelled RC beams and the rigid diaphragm adopted to simulate the concrete slab (a very common configuration in RC buildings) may cause the development of unintended fictitious axial forces in them.

Consider re-bar stresses form analyses rather than yielding stresses for the calculation of horizontal shear force demand in Joints Checks
This is an option employed only in the nonlinear methods of analysis. If this option is checked, the calculationsfor the horizontal shear force demand in the Joints Checks are carried out employing the actual stresses of the re-bars(as calculated from the nonlinear analyses), rather than the stresses at yield, which are considered in the typical calculations for linear analyses that employ the capacity design philosophy.