Program Description:

LIVE calculates the live load reaction at a pier for one line of wheels (half a lane) given lengths of the back and ahead spans on the stack. It includes impact and calculates a weighted average impact for the live load reaction.

The display gives the reaction in kips including impact. The status window shows whether lane load or standard truck loads controlled. If truck loads controls, the direction of the truck is shown with an arrow. The impact factor is also shown in the display window.

For the truck load case, one 16 kip load is placed over the bent and an impact value of 1.3 is used. I did this because the controlling span length over a bent would be the beam spacing so the value would always be 1.3. A second 16 kip load is placed 14 feet away on the longer span. The 4 kip load is placed 14 feet away from the bent on the shorter span unless the longer span is more than twice as long as the shorter span in which case the 4 kip load is placed 28 feet from the bent on the longer span. Loads on the spans are given their appropriate impact factor and a weighted average is figured. Therefore, dividing the given reaction by the average impact will give you the reaction without impact. Spans are assumed to greater than 14 feet but may be less than 28 feet. Military loading is also checked with two 12 kip wheels.

Lane load is calculated with 320 pounds per linear foot with the appropriate impact factor of the back and ahead spans. The concentrated load is 13 kips and an impact factor of 1.3 is used for the same reason as above.

The program IMPACT is called by LIVE so it must be present for the program to run. Variables IT, IL, PT, PL, L1, L2 are created and purged. User flag 1 is used for direction of truck but is cleared at the end of the program. The program leaves number readout fixed to 5 decimal places. The program is very slow and could perhaps be speeded up by using the stack or local variables rather than the global variables.