Over-straining the reinforcing can occasionally be an issue for more typical steels when assuming the maximum allowable concrete strain. For instance a deep section with a wide compression face (e.g. single or double tee) with light reinforcing. The depth in compression to the neutral axis is...
I had thought the main difference in efficacy between the two is that N95 use head straps while KN95 uses ear loops. Bushy faces aside and with proper sizing, head straps are better even if the filter material is the same. Is that correct?
If you're running into a problem with a low rebar ratio then you have the option of adding more reinforcing instead of concrete, which may also reduce the size effect.
ACI318-19 just refers you to the Handbook for further discussion of alternate models. I believe AcK1 was a catch-all term for modes of shear resistance, other than friction, on the interface (Ac) such as mechanical interlock, dowel action, and maybe cohesion. K1 was an empirically derived shear...
It means that there is no need to add shear tension at sections where the flexural/axial/torsion tension force is at a peak. For instance midspan for positive flexure, or over a continuous support for negative flexure. In figure 8.2.8.3 this situation is shown as the flattening of curve B near...
Those terms are specific to ACI's shear failure model for prestressed beams, using the more detailed method. HTURKAK's diagram illustrates where each may be critical, though you generally check both at each section.
Koot, both of your figures look like a web shear failure to me. Cracking above...
Bridges usually use a variable depth haunch between the girder and the deck. It allows for the camber and the difference between the girder profile and the final deck/roadway profile. The camber and profile difference often counteract each other to some extent.
Have you accounted for the camber reduction from the weight of the topping itself? If not, it could account for a large chunk of what you are trying to remove.
You should talk to some of the eligible hollowcore providers in your area for guidance on specifying their product. They will probably do the detailed design themselves based on your requirements (e.g. layout and loading).
For your own education you can obtain a copy of the PCI Hollowcore...
In an interview I saw with Robert Mitchell he mentioned by when flying in formation you have to pull away from the other aircraft when there is a problem. I imagine that really complicated the situation for him in terms of trying to stay near level in a climb. He also speculated, from a dot on...
The calculation of Act is intended to be an approximation to avoid the need for a cracked section analysis. The Canadian codes simply defines it as the area of concrete on the flexural tension side of the member (as in AS3600-2018). FIB is referring to the middle of the effective shear depth...
https://www.google.com/maps/@44.1741427,9.9250294,408m/data=!3m1!1e3
https://www.google.com/maps/@44.1731868,9.9264993,3a,44.4y,309.43h,86.15t/data=!3m6!1e1!3m4!1sfQxb81kyhULIctFpPvsLUQ!2e0!7i13312!8i6656
Concrete arches with open spandrel. This Guardian article...