Truss Solver

Results File Format


The Results file is an ASCII (plain text) file which includes all the model, loads, restraints and solution information. The Results file for the built-in example truss is shown below. This file is tab delimited to make it easy to import into a spreadsheet. The file is divided into sections. Each will be discussed separately below.

Note that all of the quantities in this file are nondimensional.

Truss Model

Number of nodes = 3
Number of elems = 3
Number of mpsets = 1

Mpset	Area	Modulus
1	1	206000

Node	x coord	y coord
1	1	1
2	3	1
3	2	4

Elem	node 1	node 2	mpset
1	1	2	1
2	2	3	1
3	1	3	1

Number of loads = 1
Load	node/elem	direction	value
1	3	x direction	1

Number of restraints = 3
Restraint	node	direction	value
1	1	x direction	0
2	1	y direction	0
3	2	y direction	0

Displacements:
Node	u	v
1	0	0
2	4.85437e-006	0
3	7.91815e-005	-8.09062e-007

Reaction Forces:
Node	Dir	force
1	x direction	-1
1	y direction	-1.5
2	y direction	1.5

Element Forces:
Elem	Axial force
1	0.5
2	-1.58114
3	1.58114

The Header Section

Truss Model

Number of nodes = 3
Number of elems = 3
Number of mpsets = 1

This section gives the number of nodes, elements and mpsets in the model.

The MPSET Section

Mpset	Area	Modulus
1	1	206000

There is one line for each MPSET in the model. On each line the first number is the MPSET number. The second is the area (1.0 here) and the third is the Modulus (206000 here).

The Nodes Section

Node	x coord	y coord
1	1	1
2	3	1
3	2	4

There is a line for each node in the model. The first number on the line is the node number. The second and third are the X and Y coordinates of the node, respectively.

The Elements Section

Elem	node 1	node 2	mpset
1	1	2	1
2	2	3	1
3	1	3	1

There is one line for each element. The first number on each line is the element number. The next two numbers are the nodes at end 1 and end 2 of the element, respectively. The last number is the MPSET number for the element (always 1 here because we only have one MPSET).

The four sections above constitute a model file.


The Loads Section

Number of loads = 1
Load	node/elem	direction	value
1	3		x direction	1

This section contains one line for each load applied to the model. The first number is the load number. The second is the node number to which the load is applied. The following text gives the direction of the load and the last number (1 here) is the magnitude of the load.

This section is all that is written to a loads file.


The Restraints Section

Number of restraints = 3
Restraint	node	direction	value
1		1	x direction	0
2		1	y direction	0
3		2	y direction	0

There is one line for each restraint applied to the model. The first number on the line is the restraint number. The next number is the node number to which the restraint is applied. The text gives the direction of the restraint and the last number is the magnitude of the displacement restraint imposed (0 means fixed or rigid restraint).

This section is the contents of a Restraints file.


The Displacement Section

Displacements:
Node	u		v
1	0		0
2	4.85437e-006	0
3	7.91815e-005	-8.09062e-007

This section contains one line for each node in the model. The line contains the node number followed by the X (u) and Y (v) displacement components.

The Reaction Forces Section

Reaction Forces:
Node	Dir		force
1	x direction	-1
1	y direction	-1.5
2	y direction	1.5

This section contains one line for each restraint specified in the Restraints Section. Each line contains the restraint number, the direction of the restraint and last number is the force needed to be applied in the restrain direction to impose the restraint.

The Element Forces Section

Element Forces:
Elem	Axial force
1	0.5
2	-1.58114
3	1.58114

This section contains one line for each element in the elements section. These element forces are the forces (positive is tension) in the bars of the truss.


End of Line Characters

There is one difference between the the Results files written by Unix and Windows versions of Truss, the lack or inclusion of a carriage return (ctrl-M or ^M) at the end of each line. This is because the two systems treat end of lines differently. Unix uses just a linefeed (\n) while Windows/DOS uses carriage-return and linefeed (\r\n), thus Results files transferred from one system to another without change may behave differently on the other system. This is not a concern if you are only using the files with Truss, as both of its versions will translate the files of the other version. This is also the reason that if you use ftp to transfer the files over the net you should transfer them as ASCII files, so that ftp will translate the end of line characters correctly.