Good morning. I have a new stair to connect two floors in a waffle slab concrete building and I have a few questions that we are hoping to clarify.
1) The stair is a 'convenience stair' as being told by the architect as it is not a 'means of egress' from the floor or building. This allows them to have some exceptions to the way they have to detail the requirements but it does not seem to change our design requirements structurally. For example, ASCE 7 has "Stairs and Exit ways" as 100 psf. Even though this building floor was designed at 60psf LL + 20 Partition LL, it does not seem we can design for less than the 100. Anyone know of any way to reduce the stair LL requirement? We are trying to limit the impact to the floor below where the stair lands and reduce the possible reinforcement required due to the tenant occupancy below.
2) Another engineer in this building had an opening cut into the slab and required the contractors to chip away the concrete to install plates with slots for the rebar to pass thru, so that they could weld the rebar fully to the plate before cutting the rebar away and demoing the waffle for the opening. I see no reason to do this as the building is mild reinforced and does not contain prestressing strands or post tensioning. The argument was that they didn't want the rebar to pull back into the slab and risk cracking the waffle rib. This has come up because that was the only other opening cut into this building and the way the owner was told it had to be, which we aren't showing on our documents at this time. We have evaluated the loss of continuity as this continuous action is no longer present and we are essentially creating an end bay in the slab direction, changing the moment distribution. Any idea why the prior designer would have required that?
1) The stair is a 'convenience stair' as being told by the architect as it is not a 'means of egress' from the floor or building. This allows them to have some exceptions to the way they have to detail the requirements but it does not seem to change our design requirements structurally. For example, ASCE 7 has "Stairs and Exit ways" as 100 psf. Even though this building floor was designed at 60psf LL + 20 Partition LL, it does not seem we can design for less than the 100. Anyone know of any way to reduce the stair LL requirement? We are trying to limit the impact to the floor below where the stair lands and reduce the possible reinforcement required due to the tenant occupancy below.
2) Another engineer in this building had an opening cut into the slab and required the contractors to chip away the concrete to install plates with slots for the rebar to pass thru, so that they could weld the rebar fully to the plate before cutting the rebar away and demoing the waffle for the opening. I see no reason to do this as the building is mild reinforced and does not contain prestressing strands or post tensioning. The argument was that they didn't want the rebar to pull back into the slab and risk cracking the waffle rib. This has come up because that was the only other opening cut into this building and the way the owner was told it had to be, which we aren't showing on our documents at this time. We have evaluated the loss of continuity as this continuous action is no longer present and we are essentially creating an end bay in the slab direction, changing the moment distribution. Any idea why the prior designer would have required that?