I posed this question over in the Structural Engineering forum, but it occurred to me that perhaps the retaining wall guys might have had some first hand experience with this. In short we have a contractor proposing to utilize salvaged steel railroad rail as reinforcement for drilled concrete piers in a soldier pile wall application. They have done this on several projects before with what they claim are barely any deflection, and they assume full composite action of the steel rail & concrete working together. The rail is a 132lb per yard section that is 7-1/8" deep, placed near the tension face of 36" diameter drilled piers spaced at 5' c/c. Maximum retained height above bedrock is 25'.
The biggest concern we have is the assumption of composite action, which may very well be the case, but we have not found sufficient evidence or research to support such behavior for encased steel sections with no shear connectors or reinforcement. In fact, AISC has specifically stated that encased sections in beam applications must have shear connectors (though they disclaim any application of their specifications to non-building applications). We have come across some research and some statements in Handbook of Structural Engineering Second Edition by Chen & Lui which seems to back up this practice, but current codes do not seem to bear witness.
Another way to look at it (perhaps more appropriate?) is to consider the steel rail as reinforcing steel in a traditional reinforced concrete section. However, the concern here is with bond and development length of the steel since it is essentially smooth. The contractor claims that in this case that 50% of the bond strength of deformed bars is appropriate, as studies have shown that "bond" is actually about 50/50 chemical bond & mechanical bond.
Has anyone had any experience with such an application? How have you analyzed such a section? See attached photo for a scale drawing of the proposed section.
The biggest concern we have is the assumption of composite action, which may very well be the case, but we have not found sufficient evidence or research to support such behavior for encased steel sections with no shear connectors or reinforcement. In fact, AISC has specifically stated that encased sections in beam applications must have shear connectors (though they disclaim any application of their specifications to non-building applications). We have come across some research and some statements in Handbook of Structural Engineering Second Edition by Chen & Lui which seems to back up this practice, but current codes do not seem to bear witness.
Another way to look at it (perhaps more appropriate?) is to consider the steel rail as reinforcing steel in a traditional reinforced concrete section. However, the concern here is with bond and development length of the steel since it is essentially smooth. The contractor claims that in this case that 50% of the bond strength of deformed bars is appropriate, as studies have shown that "bond" is actually about 50/50 chemical bond & mechanical bond.
Has anyone had any experience with such an application? How have you analyzed such a section? See attached photo for a scale drawing of the proposed section.
