Structure Type



Enter the type of and the basic data for structural analysis. 



From the Main Menu select Structure > Type > Structure Type.. 


Structure TypeSelect an option as to whether the analysis is to be carried out in 3D or 2D. 3D: 3D structural analysis XZ Plane: 2D analysis in GCS XZ plane YZ Plane: 2D analysis in GCS YZ plane XY Plane: 2D analysis in GCS XY plane Constraint RZ: 3D analysis constraining rotational degreeoffreedom about GCS Zaxis Note Use the function to exclude unnecessary degreesoffreedom to ensure the efficiency of the analysis. Quite often, only 2D behaviors or behaviors with a particular degreeoffreedom constrained are of interest. 3  D X  Z Plane Y  Z Plane X  Y Plane Constraint RZ Revision of Civil 2011 Mass Control Parameter Define mass type as Lumped Mass or Consistent Mass. The user can consider whether to convert the model selfweight into lumped/consistent masses for dynamic analysis using the Convert Selfweight into Masses option.
Lumped Mass
Convert into lumped masses. The total mass of an element is directly distributed to the nodal points of an element. In general, only the diagonal terms of the lumped mass matrix are considered for mass calculations. Offdiagonal terms are zero.
Consider Offdiagonal Masses
When this option is checked on, all terms including offdiagonal terms in the lumped mass matrix are considered for mass calculations. The accuracy of results increases with a full lumped mass matrix, but the analysis time may increase. When ’r;Consider Offdiagonal Masses’ option is checked off, the matrix is considered as a vector. When a section offset is considered, a node will be generated at the offset location and the loads, boundary conditions, masses, etc. to be applied to the node will be entered to the node at the offset location. However, structural characteristics related to elements (e.g., element stiffness, loads to be applied to the elements, masses converted from selfweight of elements, etc.) have to be entered at the centroid of a section. If this option is checked, masses converted from selfweight of elements are entered at the centroid of a section. Nodal mass and nodal load, which is entered at the node and has no relation to elements, will be entered at the offset node.
Note 1 Offdiagonal Masses can be reflected in the time history analysis.
Note 2 When ’r;Mass Offset’ is used, only Lanczos method will be supported for the Eigenvalue analysis.
Note 3 When ’r;Mass Offset’ is used, the Section Offset of a beam element will be taken into account. ’r;Mass Offset’ will be effective only in beam elements.
Consistent Mass
Convert into distributed masses. Consistent Mass is calculated with the shape function used to derive the stiffness matrix. Offdiagonal mass terms are considered and, unlike the lumped mass, the inertia coupling effect is considered. Therefore, results using the consistent mass is more accurate than the lumped mass, however it takes more time for numerical computation. Consistent masses can be applied only when the "Lanczos" option is selected in the Eigenvalue Analysis Control.
Convert Selfweight into Masses
Convert to X, Y, Z: Convert the selfweight into lumped masses in the GCS X, Y, Zdirections
Convert to X, Y: Convert the selfweight into lumped masses in the GCS X, Ydirections
Convert to Z: Convert the selfweight into lumped masses in the GCS Zdirection Note
1 When dynamic analysis is performed with "Do not convert" option checked, mass effect cannot be reflected in the analysis. If 'Convert to X, Y, Z' is selected, the mass, which is the weight divided by the acceleration of gravity, is automatically considered in the GCS X, Y, Zdirections. The weight itself is automatically obtained by multiplying the volumetric weight (density) entered in Model > Properties > Material by the volume of the element. If 'Convert to X, Y' is selected, the calculated mass is automatically considered in the GCS X, Ydirections. If 'Convert to Z' is selected, the calculated mass is automatically considered in the GCS Zdirection. In most cases of building structures, lateral behaviors are more important than vertical behaviors. Thus, the vertical components of masses are commonly neglected. The condition of 'Convert to X, Y' saves analysis time and lessens the burden of computer memory capacities. Where structures are analyzed considering only the vertical component of the seismic data or dynamic analyses are required to evaluate machine vibrations on floor slabs and other vertical vibrations, 'Convert to Z' may be more appropriate. The notion is identically applied when masses are generated by "Nodal Masses" or "Load to Masses". For line elements (truss element, tension element, compression element, beam element), each element mass is divided by two and distributed to both ends as lumped masses. For plane elements (plane stress element, plate element) and solid elements, each element mass is divided by the number of nodal corners and lumped to each node as lumped masses. Self weight cannot be converted into mass in Load to Mass. It must be converted in Structure Type.
Note 2 Consistent Mass can be reflected in the time history analysis.
Note 3 When ’r;Consistent Mass’ is used, only Lanczos method will be supported for the Eigenvalue analysis. Gravity accelerationEnter the acceleration of gravity considering the unit system in use. Initial TemperatureEnter the initial temperature required for a thermal stress analysis.(Refer to Load > System Temperature or Nodal Temperature) Align Top of Beam Section with Floor (XY Plane) for Panel Zone Effect/DisplayAlign the tops of line elements in the GCS XY plane such that their top elevations line up at the floor level (nodal positions of columns) when reflecting rigid offsets or displaying the elements in the Model Window. (Refer to "Rigid Offset Distance") Note Align Top of Slab (Plate) Section with Floor (XY Plane) for DisplayAlign the tops of plate elements in the GCS XY plane such that their top elevations line up at the floor level (nodal positions of columns) when displaying the elements in the Model Window. Note 
