Error Percentage in Finite Element Analysis and Solutions

No structural element should have its length, thickness, or modulus of elasticity set to zero. Setting these values to zero causes the element to demand infinite displacement.

If the mass of elements is given as zero, the system cannot be solved in the modal analysis option using finite elements that operate with a mass matrix, or the mode values come out as undefined.

If there are walls resting on the slab of an upper storey, drawing beams at the lower storey ceiling with a height equal to the slab thickness and a width equal to the width of the wall above, or solving with an irregular triangular mesh as described at Partial Error in Load Transfer and Slab Finite Element Mesh Option, increases the accuracy of the analysis.

If one wall is connected to another wall at a mid-region point rather than at its end nodes, it is not necessary to split the intersected wall. StatiCAD performs automatic corrections during analysis.

As is the case with a soft storey, wall segments of 1–2 cm remaining between doors and windows must be deleted (or the FEM sensitivity value must be reduced so that the start and end points of the small wall segment do not connect to the same node). After deletion, the beam above the door and window can be made into a single piece.

Balcony parapet walls should not be included in the model. Because they are not connected to the diaphragm, it is more accurate to enter them into the system only as loads rather than having them take a share of the storey earthquake shear force. If they must be included in the system (in V7 and later versions), a solution without a rigid diaphragm can be performed.

Extra beams should not be drawn on walls in the direction of the wall.

If an element in the finite element model is unsupported/disconnected and floating in the air, it corrupts the finite element system matrix and may cause all values in the system to come out as zero or infinity.

When the FEM sensitivity value is changed in the project general settings, the program merges nodes within the specified distance. If the start and end nodes of an element become the same, it will cause an error in the analysis; therefore, in buildings with very small elements, the FEM sensitivity value can be reduced.

For users of V8 and later versions, element definitions must be made from defined axes as described at Option to Consider Grid Line Eccentricities in Modeling with StatiCAD V8.

For V7 and earlier version users:

Slabs must be connected to walls and beams from the centre axis. In cases where they are not connected from the centre axis, the program may consider the relevant edge of the slab as disconnected (depending on the FEM sensitivity value in the project general settings as well).

Element intersections must be made from the centre axis. The centre axes of elements must be used for wall-to-wall and beam-to-wall connections. Beam-to-vertical bond beam connections do not need to be made from the centre axis (for V5.3.7.5 and later); the program automatically creates link elements. For V7 and earlier versions, you can access the related video by clicking here.

Before sending your project as a support request, please install the latest version of the program and try to solve it.