Pouring a new mat foundation (supported on piles) right beside an existing mat foundation that is supported on piles. New equipment, with a housekeeping pad, will be added on top of the existing mat slab. We specified to cut out part of the existing mat to accommodate the new construction, but...
Thanks for the responses. It's what I was expecting, just thought I would throw it out there to see if someone could bail me out and save me some design time.
In a multi-storey building, the diaphragm action will be provided by several horizontal trusses in each floor (the floor is grating).
Can this be modelled as a rigid diaphragm? When modelling the trusses individually, horizontal deflections are below 2 x story drift, although one level is...
thread507-496992
Similar to what was discussed in a previous thread, I am looking for guidance related to the overturning capacity of a steel multi-story braced frame. I'm worried I'm being overly conservative, but looking for a sanity check. My initial interpretation is that the overturning...
atrizzy, I have done some preliminary calculations. The length of some braces is long, so the tension capacity is much larger than compression in some cases. For tension-only, the horizontal force can be much larger than that associated with buckling, which results in a large footing. It is...
Thank you TLHS.
Skeletron:
But what about Conventional Construction (CC)? I understand that for LD or MD braced frames that buckling and redistribution is considered in the steel design, so the SFRS capacity would be based on yielding of the tension member (plus a little post-buckling...
Question regarding foundation design for earthquakes. A clause in the Canadian code requires foundations to resist the overturning capacity of the SFRS, not the applied loads only. (The idea is to avoid having the foundation be the yielding element in the event of higher-than-expected seismic...
I am designing web stiffeners for an existing roof beam to accommodate a new rooftop platform. The existing web cannot support the full factored reaction related to the future platform. The intent is to construct the platform prior to welding the web stiffeners. The full factored load will not...
We have concrete columns sitting on a mat foundation. We have designed pyramid-shaped "inverted capitals" at the bottom of the columns to help with punching and slab moments, and the application of waterproofing. Canadian standard A23.1 specifies that capitals are to be poured monolithically...
Any experience with urea containment? We are designing a concrete containment dyke around a urea tank with a 32.5% urea concentration. The concrete will not be continuously exposed to the urea; the dyke will be there in the event of a tank rupture.
What will the urea do to the concrete? I am...
BA: The drawings specify top steel (minimum) at the intersection of middle strips, so I think we'll be alright. From what I can tell, the top steel is there for deflection only; I don't see any way the slab would bend upwards at these locations.
I ignored distributing the moment. I checked...
It is an existing slab. I don't think the anchorage is up to us; i think the jib crane provider designs the connection. We just need to check the slab.
If not, we would likely go with a bunch of long adhesive anchors. We don't have access to the slab underside; there is a large water tank...
Hi,
I'm checking a 10" slab for the installation of jib cranes. The jib cranes will apply a concentrated moment on the slab, near mid-span. The jib cranes will be located in several places; sometimes in column strip, others in the middle strip.
How much of the slab contributes to the...
We have a parking garage that is constructed of precast concrete double tees that are supported by precast beams and columns. A number of joints between the double tees are leaking and must be repaired. There is a 3" traffic topping.
One repair method we want to avoid is to chip away the 3"...
Thanks for the responses everyone.
What we have decided to do: Since the top slab is sloped, we have to pour some concrete anyway to level it for the equipment. So we are going to pour this new concrete about 5" or 6" thick and dowel it into the existing slab, to give us about 13-14" of slab...
I'm checking an existing concrete slab on grade for new equipment loads. The existing 8" slab was poured on top of an older 6" slab-on-grade; only friction connects the two.
I will assume that the two slabs do not act together. How does the lower slab (that is directly on grade) effect the...
This question might be silly, but are all double Tees prestressed concrete? I'm looking at a building from 1968. The drawings I have provide no reinforcement details regarding the double Tees (4 ft wide, 16" deep including 2" slab). There's a 3.5" topping. Spans are 30 ft.
I always thought...
