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  • Users: umrce
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  1. umrce

    Skewed Slab Span Bridge

    AASHTO very explicitly outlines the criteria when the transverse deck reinforcement can be skewed up to a certain angle. My understanding since this is in Chapter 9, is that it only applies to decks on beams. So my question is what's everyone's opinion on skewing transverse reinforcement slab...
  2. umrce

    Continuous Reinforcement Requirements

    This is an incredibly tedious question so bear with me. I'm trying to terminate some negative moment reinforcement and AASHTO Section 5.10.8.1.2c states that At least one third of the total tension reinforcement provided for negative moment at a support shall have an embedment length beyond the...
  3. umrce

    Sounding Bridge Deck for Repairs

    I sounded a bridge deck a few years ago (we dragged it with chain to look for delamination's) and while visually it appeared to be in good condition it sounded terrible. I probably had 80% of the surface indicating repairs. We later found our from the transportation agency that owned/maintained...
  4. umrce

    Bonding Strength of Concrete in Tension

    I'm evaluating a demo for a contractor and we're investigating whether or not they could lift a non-composite slab off a precast beam in sections. One concern I have is that the flanges of the PCB are fairly thin so I was going to check for an uplift condition as they "pop-off" the slab. My...
  5. umrce

    Desperately Need a Sketching Program!

    I do structural engineering and we regularly use a program called Tedds (by Tekla) that lets you perform calculations in Microsoft Word. My biggest complaint is that it doesn't have the ability to do digital sketches to support the calculations and drawing in Word is exhausting. If I really...
  6. umrce

    Bend Rebar for a Large Radius?

    I primarily design bridges where I often run into a very large radius on a curved bridge deck. I've never specified pre-bending the deck reinforcing that runs longitudinally along the length of the bridge. I've always assuming that since these bars are typically no larger than a #6, that they...
  7. umrce

    Interpretation of LRFD Bridge Design Spec

    I'm looking for other's opinion on how to interpret Section 5.7.4.2 regarding the use of a reduced effective area for design in Seismic Zone 1. The code requires the percentage of steel in the reduced effective area to be the greater of either 1% or the value obtained from the following...
  8. umrce

    Cover Plate Thickness

    I recently had a fabricator request increasing a cover plate thickness, here are the parameters of the situation. Flange thickness = 1.34" Cover Plate thickness = 1.5" Requested CP Thickness by contractor = 1.75" Normally I wouldn't hesitate to approve the request but AASHTO LRFD limits the...
  9. umrce

    Waler Detail for Tieback Anchored Sheet Pile Wall

    We're designing a sheetpile wall that is tall enough that it will require a waler with angle tiebacks. Would anyone like to provide there opinions on, and maybe an example of how to detail the waler and tieback. The last project we did the waler was a double channels welded horizontally to the...
  10. umrce

    A Discussion on Efflorescence

    I've recently had a client claim that the efflorescence from a beam was dripping onto cars in their parking garage and removing the paint on the tenants cars. I've never heard that before and as a young structural engineer was under the impression that other than helping me locate cracks, these...
  11. umrce

    Pile Bent Design

    I recently designed a pile bent and had a very difficult time getting a design to work. Scour combined with the longitudinal temperature forces killed the pile design due to bending. My supervisor, a well respected bridge engineer in our state has since told me that in the good 'ole days they...
  12. umrce

    A709-50W Steel Plate Availability

    I'm having a disagreement with a coworker and I'd like to hash it out on the forum. I have several references that conflict each other on the availability of A709-50W steel plate thicknesses. Two references (National Steel Bridge Alliance and the FHWA) both recommend thickness intervals of 1/8"...
  13. umrce

    Scales for Plan Details - For Structural Drawings!

    I know this is a structural forum but my question is directed to structural/civil engineers. My supervisor talks has told me in vertical structures such as buildings, the plan details are commonly drawn in various scales: 1/2", 3/4" etc. and that these scales are specific to the detail being...
  14. umrce

    2-D Lateral Earth Pressures on Stepped/Tiered Sheet Pile Walls

    Please see the attached sketch as this may get confusing... I have a sheetpile wall (SP-1) behind an existing bridge abutment wing and beyond. Behind the wing, I'm relying on the the wing to act as a waler for SP-1 per my very experienced bosses recommendation). Beyond the wing SP-1 is a 15ft...
  15. umrce

    Various Types of Bearing in Bridge

    I have a bridge rehab project where we are widening the bridge and adding beam lines. Typically on projects like this if the existing bridge is in good shape, the DOT requests we replace the deck and reuse the old I-beam superstructure making repairs as necessary. Our bearing assemblies for the...
  16. umrce

    Shear Friction with Mechanical Rebar Couplers

    I have a phased project where I will have a cold joint in a beam so I am checking it for shear friction. Because of clearance issues at the joint we have to use mechanical couplers at the face where I'm checking shear friction. Will the couplers being present affect my capacity? I would assume...
  17. umrce

    Axial Member Reduction in Area for Shear Analysis

    I'm analyzing a wall per AASHTO that does not meet the min. 1% requirements of section 5.7.4.2 so, per the code, I am using a reduced area (or width, b) for modelling. The wall is for a RCB so it has some significant shear due to the lateral earth pressure. Should I follow thru using a reduced...
  18. umrce

    Old Paper - Davisson and Robinson (1965)

    Anyone know where I could get a copy of Davisson and Robinson. 1965. "Bending and Buckling of Partially Embedded Piles." It was originally from the Sixth International Conference of Soil Mechanics and Foundation Engineering.
  19. umrce

    Confused by new AASHTO (5th Ed.) crack control equations

    We were having a discussion in my office about AASHTO's (LRFD 5th Ed.) new method regarding crack control 5.7.3.4. Many people here believe it is counter intuitive (and thus incorrect) for you to have a tighter max bar spacing for more concrete cover (or a lower allowable stress in the bars). I...
  20. umrce

    Need Help! - Antiterrorism Design for Military Facility

    I will be very vague as I'm sure they're listening... (joking) I am currently working on an military installation and we are adding some ventilation openings in existing masonry walls (that are NOT designed for blast resistance) however, the design team has been reinforced several times by the...

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