National Steel Bridge Competition 2013

Portland State University

Weight 125 lbs.Length 194.00 in.Width 38.00 in. Height 25.00 in.Rectangular Stock 2.00 in.Round Stock 1.00 in.Truss Ht. 6.00 in.

Bridge Details

Executive Summary

Portland State University (PSU) is one of the leaders of sustainability in higher education. As an urban campus in the heart of downtown Portland, the school’s motto “Let Knowledge Serve the City,” serves as a reminder to all who attend that what we learn is to be used with an ethic of service and purpose. With approximately 25,000 students and 124 degree options, PSU is a great resource for the Portland Metro area and Southwest Washington. Portland State University’s Steel Bridge Team resides in the Pacific Northwest Conference, home to schools from Oregon, Washington, Idaho and Alaska.

This year’s final design configuration was a group effort. As a group, we discussed several possible design options and, after optimizing member dimensions, used modeling to assess the performance of each individual design. Comparing weight, expected deflection, fabrication time and ease of construction, the 2-D truss standing before you was selected for the final design. Before building, the strength of individual member and connection type were checked and found to be satisfactory.

Aknowledgements:Brad Bart, Greg Glaze, Evan Kristof, Tom Szymoniak

STEEL BRIDGE 2013

Limit State:Variable DefinitionsPn = Nominal Tensile StrengthFy = Yield StrengthAgp = Gross Area for PipeAgr = Gross Area for Rectangular TubeTu = Required Axial Strength

Steel Properties Fy = 36 ksiAgp =[p(1.06252-0.87252)]/4Agp = 0.289 in2

Agr = lwo-lwi = 2*1-1.875*0.875Agr = 0.359 inPu = 4.053 k (from STAAD modeling)

Design for Tensile Yield F.O.S.Pn = FyAg

F.S. = Pn/Tu

F.S. = (FyAg)/Tu

F.S. = (36ksi)(0.289in2)/4.053k = 2.57