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...
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...
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...
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"...
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...
I have a question concerning "trussed" or "bent" slab rebar. I want to determine the number of top bars I have at each column. I do not have the Typical Details drawing, so I do not know the lengths of the bar bends. The slab schedule indicates that the bent bars extend about 1/3 of the span...
I'm checking the capacity of a reinforced concrete slab from 1944 in Canada. Allowable stress design was used. The steel is specified as "hard grade billet" with a working stress of 20 ksi. f'c is specified as 2500 psi.
I'm trying to figure out the yield strength of the rebar. I've done...
I'm looking for the best way to calculate the wind load on an enclosed material handling gallery. The gallery consists of two 2.75m deep trusses, 4.2m apart. The gallery is about 200m long (spans approx. 30m) with a max height of about 50m (13 degree slope).
Any thoughts on calculating wind...
I have a steel moment frame. The beam in the frame supports steel joists connected to the top flange only. Can I rely on the joists to brace the beam for the axial force it carries, or is my unbraced length the entire length of the beam?
When designing a wall using S-Concrete, my unfactored moment resistance has a value, but the factored resistance is zero. This happens for only certain walls. There is no indication of buckling, and it is a very shallow wall. Using ACI design standard.
Hi, I'm working with hollow tubes for poles (cantilever bending). I'm trying to estimate where the tube will buckle - I'm currently using diameter from the base as an estimate, but I'm having difficulty confirming this anywhere.
