BELLOWS-ACTIVATED JOINTS SIMULATORS

METAL BELLOWS, FILLED WITH A LIQUID HAVING A HIGH COEFFICIENT OF EXPANSION, ARE BEING USED FOR TESTING SEALING SYSTEMS FOR THE WORKING JOINTS OF STRUCTURES. BELLOWS ARE LESS EXPENSIVE THAN ALTERNATE METHODS, AND THEY REQUIRE NO POWER AND NO MAINTENANCE. A LARGE AMOUNT OF MOTION CAN BE OBTAINED FROM A RELATIVELY SMALL BELLOWS. THE THERMAL EXPANSION AND CONTRACTION OF A 75-FT. STEEL BEAM CAN BE DUPLICATED WITH A BELLOWS ONLY 7 IN. LONG. THE THERMAL MOVEMENT OF A 60-FT SLAB OF CONCRETE IS DUPLICATED IN AN APPARATUS SMALL ENOUGH TO HOLD IN ONE HAND AND PUT INTO A LABORATORY COLD BOX. BELLOWS CAN BE COMPACT BECAUSE THEY UTILIZE FLUIDS WHICH HAVE VERY HIGH COEFFICIENTS OF AND BECAUSE THEY CONVERT VOLUMETRIC EXPANSION TO LINEAR MOTION. BELLOWS GET LONGER AS THE FLUID EXPANDS WITH NO SIGNIFICANT CHANGE IN DIAMETER. TWO BELLOWS-ACTIVATED TEST MACHINES ARE DESCRIBED: A ROOF JOINT SIMULATOR AND A HIGHWAY JOINT SIMULATOR. THE ROOF JOINT SIMULATOR DUPLICATES THE THERMAL MOVEMENT OF AN EXPANSION JOINT IN A ROOF AND IS INSTALLED OUTDOORS TO EVALUATE ELASTOMERIC SHEET ROOFING. IT STRETCHES ROOFING SAMPLES AS TEMPERATURE FALLS AND ALLOWS THE SAMPLES TO RETRACT AS TEMPERATURE RISES. THE COMPONENT PARTS INCLUDE TWO PARALLEL STEEL MOUNTING PLATES, WITH STUDS FOR ATTACHING 10 SPECIMENS. ONE PLATE IS FIXED TO THE FRAME, THE OTHER IS FREE TO MOVE IN A HORIZONTAL PLANE TOWARD OR AWAY FROM THE FIXED MOUNTING PLATE. THE GAP BETWEEN THE MOUNTING PLATES IS THE SIMULATED JOINT. THE TWO STAINLESS STEEL BELLOWS, FILLED WITH ACETONE, ARE PLACED BETWEEN THE MOVEABLE MOUNTING PLATE AND THE FRAME. A SPRING-DRIVEN, 7-DAY CONTINUOUS RECORDER IS USED. THE HIGHWAY JOINT SIMULATOR IS DESIGNED TO COMPRESS RATHER THAN STRETCH THE SPECIMEN AND IT IS SMALL ENOUGH TO FIT IN A COLD BOX OR OVEN. FREON REFRIGERANT, WHICH IS NONFLAMMABLE, IS USED IN THIS BELLOWS. THERMAL RESPONSE OF THIS DEVICE WAS DESIGNED TO EQUAL THAT OF A 60-FT. SLAB OF CONCRETE. SCHEMATIC REPRESENTATIONS OF THE SIMULATORS ARE PRESENTED. THERE ARE MANY WAYS THAT A FLUID-FILLED BELLOWS CAN BE USED TO DUPLICATE THE THERMAL MOTION OF STRUCTURES.

• Supplemental Notes:
  • Vol 9, No 7, PP 20-22, 46, 3 FIG, 1 TAB, 1 PHOT, 16 REF
• Authors:
  • Fetter, E C
• Publication Date: 1969-7

Media Info

• Serial:
  • Materials Research and Standards
  • Publisher: American Society for Testing and Materials (ASTM)

Subject/Index Terms

• TRT Terms: Acetates; Beams; Contraction; Coolants; Joints; Liquids; Metals; Pavements; Roofs; Simulation; Solvents; Steel; Structural analysis; Structural mechanics; Thermal expansion; Training simulators; Transducers
• Uncontrolled Terms: Acetone; Structural behavior
• Old TRIS Terms: Bellows; Freon; Joint
• Subject Areas: Geotechnology; Highways; Materials; Pavements;

Filing Info

• Accession Number: 00216866
• Record Type: Publication
• Files: TRIS
• Created Date: Sep 22 1994 12:00AM