Concrete Shear (ACI)- Historical (1950)
Concrete Shear (ACI)- Historical (1950)
(OP)
In looking at many older concrete structures, it seems to be very common to see stirrup spacing on the order of the member depth. I've generally ignored any contribution of these stirrups since they would not intercept the assumed 45 degree failure plane. A couple of questions to anyone who has evaluated similar structures, or is familiar with the ACI code from that era:
1) Was there a different design approach for shear in/around 1950 that allowed these to be included in shear strength calculations?
2) Was there a requirement similar to today's code that required minimum stirrups at d/2 spacing when actual shear exceeds 1/2 of the member shear strength?
Thanks
1) Was there a different design approach for shear in/around 1950 that allowed these to be included in shear strength calculations?
2) Was there a requirement similar to today's code that required minimum stirrups at d/2 spacing when actual shear exceeds 1/2 of the member shear strength?
Thanks






RE: Concrete Shear (ACI)- Historical (1950)
This is the major challenge with renovation projects from this era since it is more difficult to reinforce member for shear than flexure.
RE: Concrete Shear (ACI)- Historical (1950)
I recall seeing an article that had mentioned the unconservative shear values, but wasn't able to put my finger on it.
Thanks,
RE: Concrete Shear (ACI)- Historical (1950)
BA
RE: Concrete Shear (ACI)- Historical (1950)
Was there a minimum steel area stipulated in order to use the increased allowable stress?
In looking through "Structural Renovation of Buildings" by Newman, he mentions the 1947 code allowed a stress .02f'c and allowed a stirrup spacing of d. He goes on to reference a Concrete International Article (Elstner "Concrete Beam Shear Design" Sept 1992 p.70) that states beams with stirrups spaced at greater than d/2 are quite safe; however, there is no mention of how to quantify. I'll try to get my hands on that article.
RE: Concrete Shear (ACI)- Historical (1950)
I could find no mention of a minimum steel area in Sutherland and Reese. If I recall correctly, the method outlined in that book was precisely the same procedure as I used when I began structural design in 1955.
BA
RE: Concrete Shear (ACI)- Historical (1950)
Oops! Guess I better keep my mouth shut...
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Concrete Shear (ACI)- Historical (1950)
BA