TR.32.2 Member Load Specification
This set of commands may be used to specify member loads on frame members
General Format
MEMBER LOAD
member-list { { UNI | UMOM } dir-spec f1 f2 f3 f4| { CON | CMOM } dir-spec f5 f6 f4| LIN dir-spec f7 f8 f9 | TRAP dir-spec f10 f11 f12 f13 }
Where:
dir-spec = { X | Y | Z | GX | GY | GZ | PX | PY | PZ }
- X, Y, & Z specify the direction of the load in the local (member) x, y and z-axes.
- GX, GY, & GZ specify the direction of the load in the global X, Y, and Z-axes.
- PX, PY, & PZ may be used if the load is to be along the projected length of the member in the corresponding global direction.
| Parameter | Description |
|---|---|
| f1 | value of uniformly distributed load (UNI) or moment (UMOM). |
| f2, f3 | distance of from the start of the member to the start of the load, and distance from the start of the member to the end of the load, respectively. The load is assumed to cover the full member length if f2 and f3 are omitted. 
|
| f4 | Perpendicular distance from the member shear center to the local plane of loading. The value is positive in the general direction of the parallel (or close to parallel) local axis. If global or projected load is selected, then the local Y component of load is offset the f4 distance; the local Z component is offset the f4 distance; and the local X component is not offset. 
|
| f5 | value of concentrated force (CON) or moment (CMOM) |
| f6 | distance of from the start of the member to concentrated force or moment. f6 will default to half the member length if omitted. |
| f7, f8 | LIN specifies a linearly decreasing or increasing, or a triangular load. If the load is linearly increasing or decreasing then f7 is the value at the start of the member and f8 is the value at the end. |
| f9 | If the load is triangular, then f7 and f8 are input as zero and f9 is the value of the load in the middle of the member. |
| f10, f11 | The starting and ending load value for a trapezoidal linearly varying load (TRAP), respectively. The trapezoidal load may act over the full or partial length of a member and in a local, global or projected direction. |
| f12, f13 | the loading starting point and stopping point, respectively. Both are measured from the start of the member. If f12 and f13 are not given, the load is assumed to cover the full member length. |
Notes
- If the member being loaded has offset distances (refer to TR.25.1 Member Offset Specification), the location of the load is measured from the initial end offset distance instead of the coordinates of the starting node .
- Trapezoidal loads are converted into a uniform load and 8 or more concentrated loads.
- A UNIT command may be on lines in between member-list lines.
- If a load location is less than zero (i.e., occurs off the starting end of the member), then it is reset to 0.0.
- If a load location is greater than the length, then it is reset to the length.
Example
MEMBER LOAD 619 CON GY -2.35 5.827 68 TO 72 UNI GX -0.088 3.17 10.0 186 TRAP GY -0.24 -0.35 0.0 7.96 3212 LIN X -5.431 -3.335 41016 UNI PZ -0.075 3724 LIN GY -6.2 -7.8
Projected Loads
If a projected load direction is specified, then the length of the member considered is that projected on the plane perpendicular to the load direction. This is always less than or equal to the actual member length. Projected loads reduce the scale of the load proportional to the projected length.
For example, if an inclined beam of total length, L, with a uniform load, w, is given the GY (global Y) load direction, then the resulting reactions are R = 1/2×L×w. However, if the PY (projected Y) load direction is used, then the projected component of the length, Lx, is used as the member length. The resulting reactions are R = 1/2 ×Lx×w in this case.
Example inclined beam parallel to the XY plane
The projected load direction, PY, uses the component length in the XZ plane for the load effect.
JOINT COORDINATES
1 0 0 0; 2 12 3 0;
MEMBER INCIDENCES
1 1 2;
…
SUPPORTS
1 3 PINNED
…
LOAD 1
MEMBER LOAD
1 UNI PY -1