Project info:
We are modeling an 8 story building that will have concrete columns & core walls for vertical support at the first 2 levels. After the first 2 floors, the columns stop and CFS bearing walls and masonry core walls carry vertical loads at the 3-8 floors. The 2nd & 3rd floors will use 2-way concrete slabs with the 3rd floor slab serving as a hefty ~22" transfer slab that is to be designed in Ram Concept. The upper floors (4-roof) utilize one-way decking that bear on the CFS bearing walls & core walls. The upper floors bearing walls all align so the load should pass down through the walls with minimal distribution to the surrounding slabs or members.
Typical floor loading: 87.5 psf DL + 40 psf LL
Roof terrace loading: 137.5 psf DL + 150 psf LL
The problem:
When we import the model into Ram Concept we noticed several strange things with the imported loads:
-The loads applied to the slab are less than what is expected when calculated by hand based on tributary areas (specifically dead load and LL)
~when trying to figure out this issue we looked at the ram Concrete module vertical reactions and compared the DL reactions at the transfer slab level with the total applied DL as presented in the "view gravity loads" viewer. We noticed the sum of reactions was always less, as much as 25% less, than the total applied loading for a given wall.
Question- WHERE ARE OUR DEAD LOADS GOING?
-Despite the walls being mostly evenly spaced and applied loading is uniform, the applied linear loading at the slab from the walls varies pretty highly from the wall start to end. In most cases the applied loading is less than what is expected, in some areas the line loading is an order of magnitude greater than expected.
Question- WHY MIGHT OUR LOADS BE IMPORTED STRANGELY IN CONCEPT WHEN ALL APPLIED LOADING SETTINGS IN THE MODELER APPEAR CORRECT?
- APPLIED DEAD LOADS IN RAM CONCRETE (TOTAL = 201 K)
- DL REACTIONS AT SLAB LEVEL FROM RAM CONCRETE (TOTAL = 151.5K)
Thanks!