In the LRFD code the fatigue shear resistance (Zr) is computed by
Zr = alpha * d^2 >= 5.5*d^2/2.
Where
alpha = 34.5-4.28 * log N
and N = number of cycles over a 75 year design life.
Rearranging, when N > 115,000,000 alpha = 0
So...
When the design N > 115,000,000 do you just use...
A question has arisen regarding the proper way to determine the shear in girder webs based upon finite element modeling.
We developed a 3D model with plate elements modeling an offset deck which is connected to the top flange via rigid links. The girders are modeled using a plate element for...
Good morning -
I am currently designing a bridge that, due to the skew of the bridge, experiences significant WEAK axis bending moments.
I interpret the LRFD code requirements to be that the section must satisfy the interaction equation and not a particular moment capacity.
Is this correct...
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When performing a grillage analysis on a composite steel I-girder bridge (plate elements with beam elements; beam ends offset to represent the "depth" of the superstructure), do you just add the plate moments to the moments in the beam to obtain your design moment.
I tried to...
The AASHTO LRFD Specifications provide for shear capacity in the "interior" and "end" panels of girder webs.
My question is:
What is the definition of the "end" panel. I assume it is a function of the web depth "D".
Thanks.
Good morning -
When designing a pier for a two span continuous structure, the controlling load for the vertical reaction is a lane load with TWO design trucks (one in each span).
When computing the BRAKING FORCE, do you use the axles for a SINGLE truck or the TWO trucks?
It is my...
Good morning-
I have a question regarding soldier pile design.
In the 17th Ed of AASHTO (ASD) Fig 5.6.2A provides an equation for active earth pressure below the dredge line with a factor of 1.5.
In the LRFD Code (Fig. 3.11.5.6-1), the 1.5 has been replaced with a factor of 0.5 for this...
I seem to recall several years ago, a supervisor had a chart from an old Army TM or NAVFAC pub that helped compute wind loads on screens or netting.
Does anyone recall this design aid or know of where I can find information on computig wind loads on screens/netting?
Thanks
