With shear friction, no dowel action should be considered. The shear resistance is equal to the clamping force times a coefficient of friction, which depends on whether the shear surface was cast monolithically, separate but intentionally roughened, etc. At ultimate, the clamping force is the...
I agree with Hilti. Shear friction means that shear across a joint causes the concrete surfaces to move relative to each other, and surface roughness forces the surfaces apart putting the bars in tension. You generally don’t count the bars that are already in tension from flexure.
Another tragedy is the lack of failure modes analysis, surveillance and monitoring, and emergency planning. There are plenty of dams around the world that have vulnerabilities. But the potential failure modes need to be recognized, continuously monitored, and planned for. Every dam whose failure...
One issue is that that everything is painted black so people don’t notice the light posts or bollards when they back up. Protective bollards are meant to be sacrificial. They will deform when hit, but are positioned far enough away so as not to damage the equipment they are protecting. But to...
Why not do the calculations with unfactored loads and determine a single factor of safety. That’s how we do it in the dam world with requirements for safety factors based on the extremeness of the loading. Also, for example, Con-Edison specifies a single 1.2 safety factor for their manholes for...
Generally Yes. You need to design the slab to span between the grade beams, and the grade beams to span between the drilled shafts. You can pour the concrete against the soil, but over time the soil will settle relative to the shaft supported grade beams.
Not sure if this could be an issue, but the in situ bedrock in this area is highly compressed. It heaves elastically when excavated then creeps significantly once the structure is built. There’s also expansive shale in the area.
I wonder if the building was originally designed as a garage that was expected to have every floor loaded to the max. Did they use live load reduction factors back in the 1920s?
When you get old like me you get used to being surpassed career-wise by others. Someone I worked with back in the 80s when we were junior engineers is now CEO of a multi-national engineering company. Why not me? It’s just not my skill set or my desire! People at your level should be able to run...
May be ok as long as there is a suitable cross member framed in at the post location. Totally wrong if not. An inexperienced engineer can overlook this. I have seen this kind of mistake with microwave antenna attachments to buildings. You can’t just bolt to a flange. There needs to be some kind...
Can you make the PT slab thickness uniform and add topping with some minimum thickness that is sloped to drain? This is what I’ve usually seen. The topping could be lightweight.
Even 1/100 inch of water would generate the same pressure as a lake. Is there anyway you can drain the area? The Schoellkopf power plant disaster is a good example. They grouted up a bunch of pesky leaks on a rock face not appreciating there was a vertical joint in the rock parallel to and a few...
For a circular footing, wouldn’t you just calculate P/A +/- M/S? For M, you could calculate a single resultant. S=Pi*d^3/32. Not easy to construct, but easy to analyze, no?
