SAP2000 tutorial course for beginners - 2: Materials definition and assigning loads

Introduction:

This is the second SAP2000 tutorial, at the end of this tutorial you'll be able to define the materials and the properties of them (Steel, concrete, etc ..), and you will be able to assign the loads at any beam (point load, distributed trapizoidal, etc ..). Moreover, the section properties and materials will be taken into consideration because they affect the deflection and the structural elements self weight.

Materials definition:

Sections built on SAP must have an ID; materials are defined so program can calculate the self-weight of the members, and to design them in advance stage. To learn how to define materials follow these steps:

1- create a new project using blank template, do not forget to determine units before creating your new project.

2- From “Define option” choose: “Materials” (see figure 1).

[Fig.1] - Define- Materials selection

3- First material to be defined will be concrete. To define a new material choose first option “Add new Material Quick” (See figure 2).

[Fig.2] - Add new quick material option

3- From the drop window “material type” Choose concrete. Now click ok. Specifications option will be kept as default in this stage.

4- A new material “4000psi-1” is now defined. Highlight this new material and choose “Modify/show system” option to modify specifications. In this stage user will only change the name of material to be concrete instead of “psi4000-1”. Other options will be discussed later.

Now click ok to finish the definition of concrete material.

[Fig.3] - Material property data

Frame sections Definition:

Lines created in SAP must have section. Thus while viewing member with extrusion option you will see a 3d view of a section.

To define a frame section follow these steps:

1- From define option choose option 2 “section proprieties” (see figure 1).

2- Choose “Frame Sections” option ➥ add new property ➥ select concrete instead of steel (see figure 4) ➥ Choose the geometry of the section (let us choose the simplest section [rectangular].

[Fig.4]

3- Change section name; usually section name includes dimensions: Rb×h.

Example: Rectangular section 50×60 is defined as R50×60.

[Fig.5] - Rectangular section definition

4- To view section properties click at “Section Properties”. See figure 6.

[Fig.6] - Property data

Creating simple 2D structural system:

A simple 2D structural system consists of line elements (beams as an example), supports (pin supports as an example), loads.

First stage will be learning how to create systems consisting of lines and supports, adding loads will be covered later.

Example 1: Use SAP2000 to create the simply supported beam shown in figure7.

[Fig.7]

Steps for building this simple structural system:

1- Determine the view you are going to work in. in this example user will work in the XZ view.

2- Build a Cartesian system consists of one spacing in the x direction. Indeed Cartesian system generates XY plane. No problem, user will only uses what he needs from grid system.

3- Cartesian system in this example will consist of 1 spacing in x, and 1 spacing in y. grid system must be as shown in figure 8.

[Fig.8] - Grid system

4- Define concrete material, and section R50×60 (already defined).

5- Keep one window open and choose the XZ view.

6- Choose “Draw Frame/Cable Element “. Besides section option choose the section you want to use (see figure 9), then drag your mouse to point A and click then drag it again at point B and click to finish.

[Fig.9] - Drawing a line in SAP2000

7- If previous steps are done in a correct way, you must get the same result as shown in figure 10.

[Fig.10] - Line R50×60

8- The final step is assigning supports. Since support at A is pin and support at B is roller (not the same support) we must select them separately. If they have common support multi selection is available.

9- After selecting point A ➥ Assign ➥ Joints ➥ Restraints ➥ Choose pin support (see figure 11).

[Fig.11] - Assigning a joint in SAP2000

10- Repeat same procedure to assign joint B.

Exercise 1: Draw structural system shown in figure 12. Distances are increasing from 1 to 6 (1,2,3,4,5,6).

[Fig.12] - Structural system for exercise

Definition of loads on SAP2000:

Before assigning loads on structural system user must define load patterns. Load patterns expression stands for defining load families (Dead, Live, wind …etc). So the first step is defining the load patterns user want to apply to the structural system. Usually users are interested in defining load patterns like: Dead, Live, Wind. Following steps are done to define these three loads patterns.

1- Define ➥ Load patterns ➥ Define load pattern window will appear (see Fig.12).

[Fig.13] - Definition of load patterns

By default SAP2000 defines a load pattern with “self-weight multiplier”=1; this to include self-weight of the section in the analysis. If user modifies the self-weight multiplier to 0 then SAP will not include self-weight in analysis.

2- To define live load pattern set the mouse cursor in the space under load pattern name and delete DEAD and write LIVE, then from Type select live instead of dead. After doing these steps just click at: Add new load pattern (see figure 14).