I am investigating a proposal by a European supplier to use shrinkage compensating agents in a slab on-grade. Their claim is that by countering the shrinkage of the concrete together with the use of steel fibre-reinforcement, much thinner slabs can be used. While the savings all-round are very...
We are looking to advise a client regarding a largish (10,000m2) slab on grade. While we have investigated a slab with saw-cut joints at regular (close) centers, the client has also had us investigate SFRC (steel fibre reinforced concrete). One of the contractors is proposing the use of a...
I am working in South Africa and at a local project have proposed "clamping" on in-situ cast concrete “corbels” on both sides of an existing bridge pier in order to allow temporary jacks to lift the bridge beams for bearing replacement. My concept is for the contractor to cast the new corbels...
I am working in South Africa and struggling to reconcile the difference in shear force capacity that I get when i run 2 different calculation streams. Our SA code doesn't have a section on shear friction, but I have a copy of the shear friction section from an old ACI code which, with minor...
I'm helping a geotechnical colleague in South Africa to calculate the shear capacity for different piles. The SA code doesn't give guidance on the calculation of Vc for circular columnns. My understanding is that ACI does. Can someone please help by posting the appropriate formula. Thanks in...
We are designing a 7 storye building that is approx 70m long. the floor plates will be post-tensioned prestress concrete. to avoid shrinkage and other problems, we have called for a joint in the building. most rule of thumb guides recommend that the joint be 40mm wide, but I can't make out...
When designing RC columns that start at foundation level, do you increase the cover for the reinforcing below ground? And then change it higer up only? Is it an option to investigate the the cost effectivenes of using some specialist cover enhancer to the sections of reinf below ground and in...
My concept design for a future parking deck over an existing roof is to use a system of structural steel beams with permanent metal formwork (sold here in South Africa under the brandname Bond-Dek). In this way the columns for the future deck can pierce the roof and the beams and concrete can...
Are there any "old timers" out there who could help by telling me what the code specified live load for an office building built in 1951 would have been. (I'm under the impression that the code governing then was CP3, but can't get my hands on a copy.)
Does anyone have an opinion on responsibilities for dimensions on shop drawings?
While we do the structural design and provide general layout drawings of structural steel members, we always ask for shop drawings for structural steel buildings from the manufacturer. We then look over the...
At the start of a project we're involved in, we made up an estimate of the masses of reinforcing that were going to be required in the building. We never summed the total estimated mass, but rather gave the quantity survyeor masses of reinforcing per cubic meter of concrete for all the elements...
I have a temporary situation where a concrete plug has to be cast into a caisson below the water table under tremie conditions. The water then gets pumped out resulting in a head of approx 4m between the invert of the caisson and the surrounding water table. (the final situation sees a seond...
We're planning to recommend the sinking of a concrete caisson for a large sewerage manhole. During winter, it is likely that the water table could rise 8 meter above the bottom of the caisson. Two questions:
1. In the equilibrium calculations, when comparing gravity stabilising forces...
Its standard practice to create joints in the cement render at the junctions of brickwork and reinf conc. But I have a project where the Architects are insisting, for aesthetic reasons, on not having a joint. I'm investigating reinforcing the render over the joint in order to accomodate the...
