Believe the info in the link is from Table 11-6 in Foundation Analysis & Design by Bowles, who in turn lifted it from a NAVFAC 1971 manual. Bottom of table listed values for rock on rock, but Bowles equates it to masonry on masonry as well. Friction angle values range from 29 to 35 degrees...
TXBRIDG,
The bridge was built in 2001 and the steel is 50 ksi. The concrete deck is not monolithic, it consists of seven 4 ft wide precast deck planks. Scanned the report you mention and had some questions. So the design practice of the beam being considered braced at the wheel load point for...
miecz
The formula for Sxc is based on the parallel axis theorems for moments of inertia. The term 1/12*b*d^3 is the moment of inertia of the flange about its own centroidal horizontal axis. The term a*D^2 is the moment of inertia of the flange area about horizontal axis of the W18 section.
I did not find in AASHTO how to calculate Sxc, it was done in the report. I have not come across Sxc before, but I do not use AASHTO much. It was calcuted in the report as below, and seems logical to me. I assume the AASHTO ASD method uses this lower value Sxc to account for lower beam...
thanks for everyones input. I found the reason for the discrepancy between the LFD and the ASD results. I guess I will describe it for anyone who may be interested. The ASD equation in Table 10.32.1A gives an allowable bending stress using Sxc, section modulus with respect to the compression...
wiktor, is that std practice to consider a steel beam as least partially braced by a concrete deck bearing on the top flange with no physical connection? seems by that logic no bridge of this type would need bracing, which does not seem to be what you see in practice.
Need some advice from any bridge engineers. Reviewing a bridge load rating report for a single span multi girder bridge for the std AASHTO truck loads. Bridge span is 26 ft and the width is 17 ft, single lane. Bridge consists of five W18x50 beams spaced at 3.96 ft, simple span. Deck consists...
