Investigation of Steel Tunnel Supports.

摘要

A series of 18steel ribs with 10ft-radius arches and 7-ft straight legs were tested to investigate the effect of loading geometry,eccentricity of load,and various section shapes used for making the ribs. It was found that symmetrical loading about the rib center line gives higher rib capacity and that closed section shapes resist eccentrically applied loads much more effectively. Square structural-tube ribs filled with concrete and one square structural tube rib with sleeve connections were tested. The practicality of using ribs made of closed-section telescoping segments is discussed. It is found that the greatest problem with ribs of this type is the tolerances required in the manufacture of sections that must slide within one another. Sleeve connections are evaluated and it is found that tolerances in section sizes are also a problem in making this type of connector practical. A study of steel rib behavior with variation of blocking stiffness and connection stiffness is described,using a computer analysis. These parameters were constant in the test series described above. Finally,results of the tests on ribs are compared with the analysis commonly used for design and is found to predict their behavior with reasonable consistency.