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  1. skewl

    Sheet pile wall design with soil springs

    Sorry for the late response, I don't check the forum often. Some more context of the site: - The steel sheet pile wall (300m long) will be a permanent structure retaining an expressway from a river. There are existing steel sheet pile walls in place, but they have deteriorated. A section of...
  2. skewl

    Sheet pile wall design with soil springs

    Thanks for the response MTSOE. It is great information and I did not find it harsh at all. I do agree with what you are saying. I’ve only considered Model B after trying for a while to make Model A work. The other context I have not mentioned is that there was a recent steel sheet pile wall...
  3. skewl

    Sheet pile wall design with soil springs

    I want to preface by saying geotechnical engineering is not my forte. I understand conventional design of steel sheet pile walls would utilize active pressure and passive pressure. At certain depth, the two sides would balance out. I would design the wall to that depth (or more to achieve...
  4. skewl

    Extent of negative moment reinforcement

    @tmalik3156 My thought would be 3 + past the inflection point would apply? Is there any reason why we wouldn't at least consider LL in your negative moment envelope? This is from the CHBDC. The Concrete Design Handbook has Figure N12.12 describing the clause. You would also need to check a...
  5. skewl

    Can anyone explain why these steel highway girders have this uniform deformed-like appearance?

    I believe this issue came up on a thin web girder bridge in Ontario. The attached report has some interesting discussions on weld distortion and tension field theory. I haven't read the report in its entirety but it seems relevant to this discussion. Due to file size (34MB) I can only share via...
  6. skewl

    10th Edition of AASHTO LRFD Bridge Design Specs

    I been taking some AISC courses and there have been a lot of reference to this 10th edition. I imagine it will be released soon.
  7. skewl

    Precast footings construction concerns

    The contractor is proposing to replace cast-in-place footings with precast footings during construction. The original design was to have the cast-in-place footings casted on top of a "leveled" mud slab. Our concern is the precast footing would not have uniform bearing with the mud slab. My...
  8. skewl

    Post-tensioning around bearing pedestal

    Seismic isn't a big deal in my region so I haven't really thought about it. But still worth a look from my end.
  9. skewl

    Post-tensioning around bearing pedestal

    Does anyone have an idea why the below post-tensioning detail was added during construction? We found the post-tensioning strands broken. However, it has been like this since 2017 and as far as I know not much has changed to the bridge. We are going out to take a look tomorrow. Potential...
  10. skewl

    Eng-Tips Salary Survey

    Ontario / Consulting / Structural 3 year EIT, but technically qualify for P.Eng. this year due to pre-grad experience 75-80k (depends on OT), 5-10% bonus I've heard some not so great stories about larger firms in the area in terms of work culture/compensation, but they are just stories.
  11. skewl

    Wide flange with stiffener plates against Torsion?

    I have used the following reference before. The whole book is obviously too big to attach but I have extracted the relevant pages (ignore my handwritten notes). Kollbrunner and Baslar (1969), Torsion in Structures - An Engineering Approach I think KootK's screenshot make reference to this...
  12. skewl

    Grillage vs Shell model

    Hi Dakka, Your question is answered in Section 8.2.3 of the 2019 FHWA Manual for Refined Analysis in Bridge Design and Evaluation. I have attached the relevant section below in case you don't have a copy. Essentially, to make your model account for "effective width", you have to refine your...
  13. skewl

    Pittsburgh bridge collapse

    Someone would have had to completed a structural evaluation (inspection and analysis) to determine the load posting. They would have modelled failed connections, section loss, verified material strengths, etc.
  14. skewl

    Pittsburgh bridge collapse

    While salt/chlorine is bad for bridges, I do think a part of the issue here is lack of maintenance over the year. Relatively speaking the bridge being 50 years old should not be in such a poor condition for so long (since 2011?). We use probably just as much salt here in Toronto and of all the...
  15. skewl

    S16-14 Handbook of Steel Construction CL26 Fatigue

    My understanding of this is a little iffy but I'd like to imagine when the member is in the fully compressed state (at -85 MPa), it experiences 180 MPa of tensile stress to bring it to 95 MPa. If the member never goes into the positive stress range (i.e. always in compression), is okay because...
  16. skewl

    S16-14 Handbook of Steel Construction CL26 Fatigue

    I believe you will have to take your stress range as fsr = 95 - (-85) = 180 MPa if it goes into tension. For your consideration, the Canadian bridge code CSA S6-19 states: 10.17.2.1 Calculation of stress range The stress range for load-induced fatigue shall be calculated using ordinary elastic...
  17. skewl

    Design prestressed bridge beam for long term downward camber

    To me, camber simply means the deflection of a girder and it is not totally related to the stress in the girder. You can cast a girder with a very large positive camber, put on some load which may lead to positive stress (tension) in the bottom fibre, but still be in a positive camber. Is the...
  18. skewl

    Tall Integral Abutment Sample Plans

    Personally I have not seen flared wingwall on integral abutment bridges, but then again I never looked too hard into it. Flared wingwall would take on more earth pressure and cause additional stress in your piles/girders/etc. NYDOT did a survey and it seems more than 50% of the surveyed...
  19. skewl

    Tall Integral Abutment Sample Plans

    Based on the manual we use in my jurisdiction, the abutment height limit is 6.0m (19.6ft). Take a look on page 3 regarding the abutment height and page 22+ for standard details. http://www.bv.transports.gouv.qc.ca/mono/1165637.pdf A rigid frame of these dimensions certainly seems possible, so...
  20. skewl

    Anchor Rod Embedment when using Anchor Rod Reinforcing

    If you extend l_dh to 20", wouldn't that mean your l_d = 0" and your anchor reinforcement no longer qualify as having enough development? So you have to use concrete breakout strength instead of anchor reinforcement strength. Your concrete breakout strength may be higher than the anchor...

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