BRIDGE VIBRATION STUDY

THIS REPORT EXAMINES THE CONDITIONS UNDER WHICH THE PHENOMENON OF RESONANCE MAY OCCUR BETWEEN CONTINUOUS HIGHWAY BRIDGES AND HEAVY VEHICLES IN GENERAL USE AT THE PRESENT TIME. IT SUGGESTS THAT THE FREQUENCY ASSOCIATED WITH THE FIRST NATURAL MODE OF VIBRATION OF THE BRIDGE SHOULD PREFERABLY NOT BE LESS THAN 5.0 CPS, AND IN THE EVENT THAT IT IS, WHAT CONDITIONS SHOULD BE SATISFIED IN ORDER TO MINIMIZE DYNAMIC RESPONSES. THE CLASSICAL AND FINITE ELEMENT APPROACHES TO THE COMPUTATION OF NATURAL FREQUENCIES OF VIBRATION OF CONTINUOUS BRIDGES ARE PRESENTED. IN BOTH CASES THE BRIDGE DECK IS IDEALIZED AS AN EQUIVALENT LINEAR CONTINUOUS ELASTIC BEAM, AND IN THE LATTER CASE THE DYNAMIC FACILITY OF THE ICES STRUDL II COMPUTER PROGRAM SYSTEM IS EMPLOYED. A TWO-DIMENSIONAL VIBRATION ANALYSIS OF A WIDE BRIDGE IDEALIZED AS AN EQUIVALENT GRID SYSTEM IS ALSO GIVEN. THE VALIDITY OF THE RESULTS FROM THE ICES STRUDL II COMPUTER PROGRAM IS ESTABLISHED BY MEANS OF A COMPARISON WITH EXACT THEORETICAL SOLUTIONS FOR PARTICULAR STRUCTURAL SYSTEMS, AND THE EFFECTS OF VARIOUS PARAMETERS ON THE NATURAL FREQUENCIES OF VIBRATION OF CONTINUOUS BEAMS HAVE BEEN STUDIED. EXPERIMENTAL RESULTS, WITH REGARD TO NATURAL FREQUENCIES AND IMPACT FACTORS, OBTAINED FROM FIELD TESTS ON ELEVEN BRIDGES ARE PRESENTED AND FOR THREE OF THESE, WHICH HAVE CONTINUOUS POST-TENSIONED CONCRETE DECKS, THE MEASURED FREQUENCIES ARE COMPARED WITH THE RELATED THEORETICAL PREDICTIONS. IMPROVEMENT IN THE ANALYSIS FOR DYNAMIC RESPONSE BY IDEALIZING THE BRIDGE INTO TWO-DIMENSIONAL GRID IS ILLUSTRATED. IT IS SHOWN THAT IN MOST CASES THE LINEAR IDEALIZATION OF THE TWO DIMENSIONAL CONTINUUM ENABLES THE NATURAL FREQUENCIES TO BE COMPUTED TO A DEGREE OF ACCURACY ACCEPTABLE IN ENGINEERING PRACTICE, AND CONSEQUENTLY IT MAY BE USED TO CARRY OUT A DYNAMIC EVALUATION AS A STANDARD PART OF FUTURE BRIDGE DESIGN. HOWEVER, A TWO-DIMENSIONAL ANALYSIS MUST BE EMPLOYED TO DETERMINE THE DYNAMIC RESPONSE OF WIDE, CURVED OR SKEW BRIDGES. A DEVELOPMENT IN THIS DIRECTION IS UNDERWAY TO OBTAIN METHODS OF ANALYSIS WHICH ARE RATHER SIMPLE FROM A DESIGNERS POINT OF VIEW. IT IS CONCLUDED THAT THE DESIGNER CAN PREDICT AND CONTROL THE DYNAMIC RESPONSES OF BRIDGES YET TO BE BUILT, PROVIDED THAT APPROACH SLABS ARE CONSTRUCTED AND MAINTAINED IN GOOD REPAIR AND THE DECK SURFACES ARE REASONABLY SMOOTH.

• Corporate Authors:

  Ontario Dept Transp, Toronto /Canada

  ,    
• Authors:
  • Cassaooly, P F
  • Campbell, T I
  • Agarwal, A C
• Publication Date: 1972-9

Media Info

• Features: Figures; References; Tables;
• Serial:
  • Volume: 81

Subject/Index Terms

• TRT Terms: Accuracy; Bridge design; Bridges; Computer programs; Dynamic loads; Finite element method; Heavy vehicles; Highway bridges; Natural frequency; Resonance; Structural design; Vibration
• Uncontrolled Terms: Dynamic response; Parameters
• Subject Areas: Bridges and other structures; Highways;

Filing Info

• Accession Number: 00208225
• Record Type: Publication
• Source Agency: Roads & Transportation Assoc /Canada
• Report/Paper Numbers: Res Rept
• Files: TRIS
• Created Date: Jan 28 1974 12:00AM