I am looking to see if anyone has experience with replacing individual steel truss members (eyebars, pins, chords) due to extensive corrosion. The two-span steel truss bridge will be closed to traffic so I am looking to find a way to relieve the load off of the member being replaced. Temporary...
Does anybody know of any studies done or publications that show the cost/benefit of Accelerated Bridge Construction? I'm looking to see the cost of the project vs. the time saved when using this method of construction. I often get questions about how much time is saved vs. how much more will...
Does anyone have experience in replacing a deteriorated timber dolphin cluster with a concrete pipe pile cluster? Due to geometric constraints, we need to replace in the exact same location as the existing timber dolphin cluster. I'm expecting the timber piles to snap when they try to extract...
Hello, I'm designing a standard reinforced concrete slab bridge and was wondering if there's any published criteria on calculating short/long term deflections of the slab? It seems that you'd still want to incorporate some sort of camber into the slab in order to provide a net long term...
Does anyone know of any requirements or specifications in AASHTO or ACI regarding the minimum spacing between legs of double vertical stirrups in a cap or beam for shear design? I'm referring to the spacing across the width of the member, not the longitudinal spacing. For wide beams, it seems...
Looking for other interpretations of AASHTO LRFD 10.6.1.3 "Effective Footing Dimensions"...
It appears AASHTO allows a reduced footing for geotechnical purposes, but this will eliminate any uplift calculation...(since the concentrated force is now centered on the footing in the effective area)...
Hello all,
How have you all distinguished between the FR and TU force calculation for a steel Fixed or Expansion Bearing? In my experience, I have applied 10% of the DL as the Friction Force for Expansion Bearings. However, AASHTO is vague on how to calculate the Thermal Force TU for a Fixed...
Hello All,
I am designing my first cross-frame (K-type) for a straight, two-span continuous bridge under LRFD specs. I am looking at a typical intermediate cross-frame, and a pier cross-frame. I have several questions regarding each:
Intermediate: Per AASHTO LRFD, it says that wind loading...
Anyone know the equivalent grade of A-7 steel? 33 ksi steel seems to be the best guess but I can never understand why they didn't associate a grade with this steel back in the day.
Bridge was built in 1952....
The bearing stiffener on a steel plate girder has been misconstructed and is offset ~ 1 3/8" closer to the center of the span from the line of bearing. Therefore the line of bearing is not acting directly on the bearing stiffener.
What kind of check should be performed? There is now an...
I will be finishing my Masters in Civil Engineering degree (MEng) with structural emphasis in 6 months through an evening program for professionals. Any idea about what sort of salary increase I should ask my employer for? I currently have 6 years experience doing structural design work for a...
I am designing a prestressed concrete bridge, and have a question regarding the haunch thickness. The haunch should account for cross slope and vertical curve camber, but what Dead Load Deflection should be used?
It seems that non-composite and composite deflections should be accounted for to...
Hi all,
AASHTO LRFD Specs indicate various Design Forces for Traffic Railings for TL-1, TL-2, TL-3 etc. in A13.2.
If you have a standard parapet attached to a wing wall, does the Transverse Force in Table A13.2-1 get transferred entirely to the wing wall? (assuming there is no moment slab.)...
If a Fatigue element passes Fatigue 1 but not Fatigue 2, is it OK? It seems possible for this to happen just based on the formula for Fatigue 2 with the ADTT, but by definition it seems that if the CAFT is reached and Fatigue 1 passes, Fatigue 2 doesn't matter.
Thoughts?
When determining the length of a dowel in a retaining wall, it appears the dowel will be in tension due to the lateral force of soil. Per ACI 12.2.2, the development length for a bar in tension results in 59" for an epoxy coated #6 bar with 3000psi concrete! Am I missing something? From other...
Since AASHTO LRFD's design load is a combination of the HL-93 Truck and Lane, do you use both the truck and lane when computing the lever rule, or do you only consider the Truck Wheel Loads?
Are the LRFD Live Load Distribution Factors applied to the HL-93 Truck Shear/Moment, the HL-93 Lane Shear/Moment, or both?
Does anyone have a reference in AASHTO where it says this? It is confusing because the LL DF tables indicate using the lever rule in some instances, which is obviously...
