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TR.41 Section Specification

This command is used to specify sections along the length of frame member for which forces and moments are required.

This command specifies the sections, in terms of fractional member lengths, at which the forces and moments are considered for further processing.

General Format

SECTION f1( f2) ( f3) { MEMBER memb-list | (ALL) }


f1, f2 , f3 Section (in terms of the fraction of the member length) provided for the members. The maximum number of sections is three, and only values between 0.0 and 1.0 will be considered. In other words, no more than three intermediate sections are permissible per SECTION command.


SECTION 0.17 0.48 0.72 MEMB 1 2
SECTION 0.25 0.75 MEMB 3 TO 7

In the above example, first, section locations of 0.17, 0.48, and 0.72 are set for members 1 and 2. In the next SECTION command, sections 0.25 and 0.75 are set for members 3 to 7. In the third SECTION command, member 8 has its section specified at 0.6. The remainder of the members will have no sections provided for them. As mentioned earlier, no more than three intermediate sections are allowed per SECTION command. However, if more than three intermediate sections are desired, they can be examined by repeating the SECTION command after completing the required calculations. The following example will clarify.


SECTION  0.2  0.4  0.5  ALL
SECTION  0.6  0.75  0.9  ALL

In this example, forces at three intermediate sections (namely 0.2, 0.4 and 0.5) are printed. Then forces at an additional 3 sections (namely 0.6, 0.75 and 0.9) are printed. This gives the user the ability to obtain section forces at more than three intermediate sections.


  1. The SECTION command just specifies the sections. Use the PRINT SECTION FORCES command after this command to print out the forces and moments at the specified sections.

  2. This is a secondary analysis command. The analysis must be performed before this command may be used.

  3. To obtain values at member ends (START and END), use the PRINT MEMBER FORCES command.

  4. If this command is specified before a steel design operation and if the BEAM parameter is set to zero, the section locations specified by this command will also be designed for, in addition to the BEAM ends. This can be used to specify three locations along the beam for design when the default sections are not sufficient. See Note 9 in AISC 360 Design Parameters.