I am currently designing a concrete bridge that has typical AASHTO girders with a concrete deck. I understand that some state design manuals sometimes add a requirement for the shear stirrups in the beam to be extended into the deck at a certain depth but I cannot seem to find a specific depth...
That might be the piece that I am missing, I appreciate your response. However, I am looking to better understand compression controlled sections in flexure simply to prepare for possible questions on the PE exam. I would never design a reinforced beam that was compression controlled in practice...
I have a bit of confusion when it comes to determining the nominal moment of a simply supported reinforced beam. Personally, I have always stuck to the method of determination being shown in the book (determine the stress in the reinforcement @ concrete failure and plug it into Mn =...
Hello,
This is likely to be a very basic question but as most structural engineers know, AISC calculates the effective length of frames in section C7.2 utilizing stiffness ratios (G). My question is this: why are the stiffness ratios calculated using the beam/girder's moment of inertia about...
Ingenuity- My thought process is that the as-built plans show a working stress that the Contractor has to adhere to. I'd imagine this working stress has to be measurable for the Contractor to confirm that required stresses have been implemented onto the girder. Therefore, wouldn't it make sense...
I am looking at a PS girder bridge from the 50's and trying to perform an analysis on the beams to ensure it can handle an increased load due to a deck modification. The as-builts indicate that 250 ksi high-strength, stress-relieved strands are to be used and state a working stress of 140 ksi...
Thank you both for your replies. I will be designing the interior and exterior girders separately so I planned on conservatively place 100% of the load on the exterior girder (since there is only a 1.5' overhang) and 50% of the load onto the first interior girder which I now know will have to be...
It seems that the distribution for dead load from bridge parapets is constantly changing in the AASHTO Specs. The latest edition (9th/2020) states "heavier concentrated line loads such as parapets, sidewalks, barriers or sound walls should not be distributed equally to the girders. Engineering...
