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  1. cooperDBM

    Mailing address in email signature

    I would need a company name and address in order to invoice them, for tax purposes if nothing else.
  2. cooperDBM

    Baltimore Bridge collapse after ship collision

    I'm surprised not to see a bumper system around the piers given the traffic under it. The power-line towers before the bridge look better protected.
  3. cooperDBM

    Linear concrete stress-strain relationship: when is it valid

    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...
  4. cooperDBM

    Excess camber growth

    If there was a net tension at the top cracking of the odd girder could see a sudden increase in the camber growth.
  5. cooperDBM

    Allowable concrete tensile stress across unreinforced plane?

    Are you accounting for any weight, including some self-weight, bearing on the top of the beam as a clamping stress?
  6. cooperDBM

    KN-95 vs N-95

    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?
  7. cooperDBM

    ACI 318-19, Table 22.5.5.1, Reduced Shear Capacity

    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.
  8. cooperDBM

    ACI dowel action in shear transfer

    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...
  9. cooperDBM

    AS3600-2018 (amdt 2) CL8.2.8.2

    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...
  10. cooperDBM

    Dwarka Expressway collapse

    Possible torsion failure in left span? Is the bridge curved?
  11. cooperDBM

    Difference between web-shear and flexure shear

    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...
  12. cooperDBM

    How is class defined?

    http://www.cplusplus.com/ https://www.w3schools.com/cpp/default.asp
  13. cooperDBM

    Largest steel span?

    Would cable-stayed be an option for you?
  14. cooperDBM

    How to Reduce Precast Double Tee Cambers

    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.
  15. cooperDBM

    How to Reduce Precast Double Tee Cambers

    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.
  16. cooperDBM

    Pre-Stress hollow core slab panel design

    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...
  17. cooperDBM

    SnowBird crash in Canada.

    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...
  18. cooperDBM

    Pretension Shear Equation

    There's a newer edition of the Hollowcore Manual available for free at Link
  19. cooperDBM

    AS3600-2018 Shear: Calculating 'A_ct'

    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...
  20. cooperDBM

    Another bridge collapse in Italy

    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...

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