Fenrim Moreover since the Wind consultants generally carry out their calculations at the center of the diaphragm of each floor, it is recommended that these points are taken in locations where are as close to the center of mass of diaphragm as possible. Refer to the discussion below for further clarification. However, the results of response spectrum analysis may be scaled to the Equivalent Static Force Method as per Clause Atkinns to Section The self-weight and imposed dead loads shall be defined separately as explained below: The primary objective of this document is to make sure that ETABS is used consistently by the structural engineers in Atkins office in Dubai ettabs terms of:. Best ETABS Manual Selecting this option will mesh the area horizontally and vertically using the selected point at the edge as reference.
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Refer to the discussion below for further clarification. The gross section area based on UBC 97 Clause This may be easily accounted for frame elements by just revising the section modifier for moment of inertia. However, the axial and bending stiffness for shell elements can not be de-coupled, i. This may cause displacement incompatibility with adjacent frame column which in turn may require revising the axial stiffness for vertical frame elements, as opposed to code explicit provisions.
Special care shall be taken when defining these labels to ensure realistic values. A wall pier can consist of a combination of both area objects shell elements and line objects frame elements. If you want to get output forces reported for wall piers, or if you want to design wall piers, you must first define them. If a wall pier is made up of both line and area objects, assign the pier label to the line and area objects separately.
A wall spandrel can consist of a combination of both area objects shell elements and line objects frame elements. If you want to get output forces reported for wall spandrels, or if you want to design wall spandrels, you must first define them. If a wall spandrel is made up of both line and area objects, assign the spandrel label to the line and area objects separately. The smaller areas are three-sided or four-sided and must have beams on all sides.
Select one or multiple lines. If the selected line passes through more than one area, all of the areas will be meshed. Note that this and the Auto Mesh Area option only work in plan view. The angle will be measured in the counter clockwise direction for the x and y-axis. If the point lies in the overlapping region of two areas, both of the areas will be meshed at the given angle.
For example, specifying a meshing of 2 by 8 means that the selected area will be meshed into 2 areas along the x-axis and 8 areas along the y-axis. The size of the meshed areas will be uniform along a given direction. Only quads and triangles can be meshed using this option. Selected Point Objects on Edges: Selecting this option will mesh the area horizontally and vertically using the selected point at the edge as reference. One more points can be selected for this type of meshing.
D Interactions with Selected Line Objects: The areas selected are meshed with the line intersecting the area. More than one line can be selected to mesh a desired area. When this menu item is clicked, all edges of the currently selected area will be split at their mid-points. If clicked again for the same selected area, they will be divided in half again, and so on.
The program does not offer any automatic meshing for walls, however, for slab elements, the automatic meshing option may be done as shown below.
Complex floor systems supporting many walls and columns e. Note In general triangular plate-bending element, with shearing deformations, produces excellent results. However, the triangular membrane element with drilling rotations tends to lock, and great care must be practiced in its application.
Because any geometry can be modelled using quadrilateral elements, the use of the triangular element presented can always be avoided. If the meshes on common edges of adjacent area objects do not match up, automated line constraints are generated along those edges.
These Line Constraints enforce displacement compatibility between the mismatched meshes of adjacent objects and eliminate the need for mesh transition elements. The following figures show the difference in results when applying auto-line constraint to a simple model where slab and wall meshing does not match. The auto-line constraint is the default option in ETABS and needs to be removed manually if required.
MANUAL FOR ANALYSIS & DESIGN USING ETABS
Akisho Etabs Atkins It should be noted that this is a necessary but not sufficient condition to ensure a sound modelling and analysis. These loads are generally calculated by recognized wind tunnel testing laboratories based on the dynamic properties of the structure as modelled during the preliminary or concept design stages. This analysis will be used in arriving at the following results; This may cause displacement incompatibility with adjacent frame column which in turn may require revising the axial stiffness for vertical frame elements, as opposed to code explicit provisions. Local Authority specific requirements are covered in Appendices at the end of this document.
Atkins ETABS Manual
ATKINS Manual for Analysis & Design Using ETABS