Elastomeric Bearing Pads Under Combined Loading

According to current American Association of State Highway and Transportation Officials (AASHTO) specification the bearing capacity of a pad subjected to rotation drops very rapidly as the bearing dimension B increases and as the angle of rotation increases. The capacity obtained by the AASHTO equation was found to be much less than what was observed to be working in the field. The objective of this project is to formulate a new design criteria for steel reinforced elastomeric bridge bearing pads subjected to axial loading and rotation. In this study a number of bearing pads were subjected to a combination of axial loading followed by cyclic rotational loading up to million cycles. The shear modulus, G, of the material plays an important role in determining the bearing capacity. In order to determine the G value for the pads used in the tests, a nondestructive technique was developed for that purpose. In addition, analytical modeling of the pads was conducted using finite element techniques. ANSYS, a commercially available finite element analysis software package, was used to conduct the analytical study. From the analytical studies and pressure sensor reading in the testing it was evident that there is a core at the middle where the stresses are the highest. Moreover, the elastomer layers reveals bulging in the lower end of the rotation just as was evidenced in the test samples. From these results one can observe the fact that the high compressive stress core moves toward the end subjected to the most compression. This behavior is in agreement with the experimental results, i.e., failure that was limited to the lower end of the rotation. Based on these experimental and analytical studies a new design equation for cases involving rotation was developed. The new equation or design procedure was formulated under the assumption that the lower side of the rotation, the end subjected to the most compression, will fail and can be eliminated. The resulting capacity of the pad will be that of a reduced pad.

Language

  • English

Media Info

  • Media Type: Print
  • Edition: Final Report
  • Features: Photos; References; Tables;
  • Pagination: 110p

Subject/Index Terms

Filing Info

  • Accession Number: 01053569
  • Record Type: Publication
  • Report/Paper Numbers: BC352-16, FSU PRJ. No. 00944
  • Contract Numbers: BC352-16
  • Files: TRIS, STATEDOT
  • Created Date: Jul 10 2007 8:06PM