Element action effects

Depending on the type of elements employed in the structural model, there can be up to ten kinds of Element action effects results, which are described in detail hereafter.

Frame element results

Frame Deformations
The deformations incurred by inelastic (infrmFB, infrmFBPH, infrmDBPH, infrmDB) and elastic (elfrm) frame elements, as computed in their local co-rotational system of reference, are provided. The values refer to the chord rotations at the end-nodes of each element (referred to as A and B, as indicated in here), the axial deformation and the torsional rotation. Note that elastic frame elements are always listed after their inelastic counterparts, even if the former alphabetically precedes the latter.  

Frame Forces
The internal forces developed by inelastic (infrmFB, infrmFBPH, infrmDBPH, infrmDB) and elastic (elfrm) frame elements, as computed in their local co-rotational system of reference, are provided. The values refer to the internal forces (axial and shear) and moments (flexure and torsion) developed at the end-nodes of each element, referred to as A and B (look in here). The possibility of obtaining the cumulative, rather than the distinct, results of each element can be very handy when a user is interested in adding the response of a number of elements (e.g. obtain the shear at a particular storey, given as the sum of the internal shear forces of the elements at that same level). Note that elastic frame elements are always listed after their inelastic counterparts, even if the former alphabetically precedes the latter.

Frame Hysteretic Curves
Hysteretic plots of deformation vs. internal forces developed by inelastic (infrmFB, infrmFBPH, infrmDBPH, infrmDB) and elastic (elfrm) frame elements, as computed in their local co-rotational system of reference, are provided.

Truss element results

Truss Forces and Deformations
The axial deformations incurred and axial forces developed by truss elements are provided here, including also the hysteretic plots.

Rack element results

Rack Forces
The internal forces developed by rack elements, as computed in their local co-rotational system of reference, are provided. The values refer to the internal forces (axial and shear), moments (flexure and torsion) and bi-moments developed at the end-nodes of each element, referred to as A and B (see in Appendix A). The possibility of obtaining the cumulative, rather than the distinct, results of each element can be very handy when a user is interested in adding the response of a number of elements (e.g. obtain the shear at a particular storey, given as the sum of the internal shear forces of the elements at that same level).

Masonry element results

Masonry Deformations
The deformations incurred by masonry elements, as computed in their local co-rotational system of reference, are provided. The values refer to the chord rotations and shear deformation at the end-nodes of each element (referred to as A and B, as indicated in Appendix A), the axial deformation and the torsional rotation.

Masonry Forces
The internal forces developed by masonry elements, as computed in their local co-rotational system of reference, are provided. The values refer to the internal forces (axial and shear) and moments (flexure and torsion) developed at the end-nodes of each element, referred to as A and B (see in Appendix A). The possibility of obtaining the cumulative, rather than the distinct, results of each element can be very handy when a user is interested in adding the response of a number of elements (e.g. obtain the shear at a particular storey, given as the sum of the internal shear forces of the elements at that same level).

Masonry Hysteretic Curves
Hysteretic plots of deformation vs. internal forces developed by masonry elements, as computed in their local co-rotational system of reference, are provided.

Link element results

Link Deformations
The deformations computed in link elements can be obtained. These consist of three displacements and three rotations, each of which defined with regards to the three local degrees-of-freedom of the link, the definition of which is described in here.

Link Forces
The internal forces developed in link elements can be obtained. These consist of three forces and three moments, each of which defined with regards to the three local degrees-of-freedom of the link, the definition of which is described in here.

Link Hysteretic Curves
Hysteretic plots of deformation vs. internal forces developed in link elements, as defined with regards to the three local degrees-of-freedom of the link, the definition of which is described in here, can be obtained.

Infill element results

Infill Deformations
The axial (i.e. diagonal) deformations computed in struts 1 to 4 of the infill element, as well as the shear (i.e. horizontal) displacements measured in struts 5 to 6, are provided here. It is noted that struts 1, 2 and 5 refer to those that connect the first and third nodes of the infill panel (defined in here), whilst struts 3, 4 and 6 connect the second and the fourth panel corners.

Infill Forces
The axial forces computed in struts 1 to 4 of the infill element, as well as the shears measured in struts 5 to 6, are provided here. It is recalled that, as discussed in here, the shear struts work only when a given diagonal is in a state of compression, hence the shear forces developed in a strut will always be single-signed (i.e. either always negative or always positive, never both).

Infill Hysteretic Curves
Hysteretic plots of deformation vs. internal forces developed in infill elements are provided here, recalling once again that struts 1, 2 and 5 refer to those that connect the first and third nodes of the infill panel (defined in here), whilst struts 3, 4 and 6 connect the second and the fourth panel corners.

Shell element results

Shell Deformations
The deformations computed in shell elements can be obtained. These consist of three displacements and three rotations, each of which defined with regards to the three local degrees-of-freedom of the shell, the definition of which is described in here. When utilising a meshed shell element the full stiffness matrix with participation of the degrees of freedom of the internal nodes (nodes of the mesh) is factorised using a static condensation procedure. As a result only the deformations of the external four nodes are output.

Shell Forces
The internal forces developed in shell elements can be obtained. These consist of three forces and three moments, each of which defined with regards to the three local degrees-of-freedom of the link, the definition of which is described in here. As noted in the case of shell deformations, when using a meshed shell only the forces of the external four nodes of the element are output.

Notes

1. Rotational degrees-of-freedom defined with regards to a particular axis, refer always to the rotation around, not along, that same axis. Hence, this is the convention that should be applied in the interpretation of all rotation/moment results obtained in this module.
2. Note that element chord-rotations output in this module correspond to structural member chord-rotations only if one frame element has been employed to represent a given column or beam, that is, only if there is a one-to-one correspondence between the model and the structure (or some of its elements). Such approach is  possible when infrmFB are used, thus allowing the direct employment of element chord rotations in seismic code verifications (see e.g. Eurocode 8, NTC-18, KANEPE, FEMA-356, ATC-40, etc). When the structural member has had to be discretised in two or more frame elements, then users need to post-process nodal displacements/rotation in order to estimate the members chord-rotations [e.g. Mpampatsikos et al. 2008].
3. Under large displacements, shear forces at base elements might well be different from the corresponding reaction forces at the supports to which such base elements are connected to, since the former are defined in the (heavily rotated) local axis system of the element whilst the latter are defined with respect to the fixed global reference system.
4. In principle, the internal forces developed by frame elements during dynamic analysis should not exceed their static capacity, derived through a pushover analysis or hand-calculations. However, some factors may actually lead to differences:
   i) if cyclic strain hardening of the rebars takes place, then this may lead to higher "dynamic flexural capacities", in particularly for what concerns the comparison with hand-calculations (where strain hardening is normally not accounted for).
   ii) if equivalent viscous damping is introduced, then the structure/elements may deform less, hence elongate less, developing higher axial load, and thus, again, higher "dynamic flexural capacity".
   iii) if the elements feature distributed mass, then their bending moment diagram developed during dynamic analysis will differ from its static analysis counterpart, and hence the shear forces cannot really be compared. (however, moments still can).
5. SeismoStruct does not automatically output dissipated energy values. However, users should be able to readily obtain such quantities through the product/integral of the force-displacement response.
6. Since in the modeling of infill panel in SeismoStruct two internal struts are used in each direction, in order to get the total strut infill panel force users need to add the values in two struts.