Tee Members with Large Web Openings

Abstract

RESULTS ARE PRESENTED OF AN EXPERIMENTAL STUDY OF MODEL AND FULL SIZE PRESTRESSED CONCRETE T-BEAMS WITH LARGE WEB OPENINGS. CONSIDERABLE INTEREST WAS GENERATED IN THE POSSIBILITY OF PROVIDING T-BEAMS WITH LARGE WEB OPENING TO ACCOMMODATE COMPLEX MECHANICAL AND AIR-CONDITIONING SYSTEMS WHICH REQUIRE A LARGE NUMBER OF DUCTS AND PIPES. THE DESIGN RESEARCH PROGRAM HAD THE FOLLOWING OBJECTIVES: (1) TO PROVIDE SUFFICIENT EXPERIMENTAL INFORMATION TO PERMIT THE DESIGN OF TEES WITH LARGE WEB OPENINGS, (2) TO CONFIRM THE VALIDITY OF SUCH A DESIGN BY TESTING A FULLSIZE T-BEAM TO FAILURE, (3) TO ASSESS THE SAVINGS IN MATERIAL AND IN WEIGHT (TRANSPORTED AND ERECTED) WHICH MIGHT PARTIALLY OFFSET THE COST OF FORMING THE WEB OPENINGS. TESTS OF MODEL T-BEAMS WERE MADE IN A STRUCTURAL LABORATORY AND THE RESULTS FROM THESE TESTS WERE USED TO DESIGN A FULL-SIZE T-BEAM. ULTIMATE MOMENTS CARRIED BY THE MODEL TEST BEAMS WERE TWO TO THREE TIMES THE MOMENT AT WHICH FLEXURAL CRACKING WAS FIRST OBSERVED. THE ULTIMATE MOMENT CARRIED BY THE FULL-SIZE BEAM (120 FT SPAN) WAS EQUAL TO 1.5 DEAD LOAD PLUS 1.8 DESIGN LIVE LOAD. IT IS CONCLUDED THAT THE DESIRABILITY OF PROVIDING LARGE WEB OPENINGS IN SINGLE-TEE MEMBERS IS OF SUFFICIENT IMPORTANCE TO THE INDUSTRY THAT FURTHER TESTING AND ANALYSIS IS JUSTIFIED.