GLUED LAMINATED BEAMS
GLUED LAMINATED BRIDGES WERE INTRODUCED TO THE AMERICAN RAILROADS IN 1944 WHEN A PANEL OF GLU-LAM STRINGERS WAS INSTALLED IN A TRESTLE OF THE TEXAS & PACIFIC RAILROAD. SINCE THEN OTHER GLU-LAM TRESTLES HAVE BEEN BUILT AS WELL AS SOME VERY LONG SPAN GLU-LAM BRIDGES. A RECENT INSPECTION OF THE VARIOUS TEST INSTALLATIONS WAS MADE AND AFTER 20 YEARS OF USE THIS TYPE CONSTRUCTION HAS SHOWN AN EXCELLENT PERFORMANCE. THE ABSENCE OF CHECKS AND GLUE LINE SEPARATIONS HAS BEEN MOST APPARENT AS CAN BE OBSERVED IN THE CAPT OF THIS TRESTLE. GLUED-LAMINATED STRINGERS FOR TRESTLE CONSTRUCTION WILL COST MORE THAN SOLIDSAWN STRINGERS, BUT FOR LONGER SPAN BRIDGES SUCH AS 60 FT, THE COST PICTURE IS DIFFERENT. FOR THESE LENGTH SPANS SOLID-SAWN MEMBERS, OF COURSE, ARE OUT OF THE QUESTION AND A CHOICE MUST BE MADE BETWEEN GLU-LAM AND OTHER MATERIALS, SUCH AS STEEL OR CONCRETE. ESTIMATES INDICATE THAT THE COST OF A 60 FT GLUED-LAMINATED SPAN MAY BE SLIGHTLY LESS THAN A SIMILAR LENGTH STEEL SPAN. THE FLEXURAL BEHAVIOR OF LARGE GLUED LAMINATED BEAMS WAS RECENTLY DEMONSTRATED AT THE RESEARCH CENTER WHEN SEVERAL 50 FT LONG SPECIMENS WERE LOAD TESTED TO THEIR ULTIMATE CAPACITY. THESE BEAMS WERE 9 IN WIDE AND 31-1/2 IN DEEP, AND EACH CONTAINED 21-1-1/2 IN THICK DOUGLAS FIR LAMINATIONS. AN ULTIMATE FLEXURAL STRESS OF 8,400 PSI WAS DEVELOPED DURING THIS TEST AND THE TOTAL CENTER LINE DEFLECTION WAS NEARLY 12 IN BEFORE FAILURE. /ARTICLE/
- Publication Date: 1967
Media Info
- Pagination: 19 p.
- Serial:
Subject/Index Terms
- TRT Terms: Bridge construction; Bridge foundations; Bridges; Construction; Economics; Flexural strength; Gluing; Laminated wood; Railroad bridges; Trestles
- Subject Areas: Bridges and other structures; Construction; Economics; Highways;
Filing Info
- Accession Number: 00208953
- Record Type: Publication
- Files: TRIS
- Created Date: Apr 21 1994 12:00AM