SUMMARY REPORT ON BRIDGE RESEARCH
THE MAJOR FINDINGS OF THE BRIDGE EXPERIMENT AT THE AASHO ROAD TEST MAY BE DIVIDED INTO 3 GROUPS: (1) RELATIVE OVERALL PERFORMANCE OF DIFFERENT TYPES OF BRIDGES, (2) MAJOR EFFECTS OF REPEATED HIGH OVERSTRESS, AND (3) ANALYTICAL CORRELATIONS OF QUANTITATIVE TEST RESULTS. THE COMPOSITE BRIDGES WERE STIFFER THAN THE COMPARABLE NONCOMPOSITE BRIDGES. TRANSIENT DEFLECTIONS INCREASED DURING THE PERIOD OF TEST TRAFFIC ON THE ORDER OF 5 PERCENT IN COMPOSITE BRIDGES, BUT ON THE ORDER OF 15 PERCENT ON THE NONCOMPOSITE BRIDGES. THE DECREASE IN STIFFNESS ON BRIDGES WITH TIME, INDICATED BY THE INCREASED TRANSIENT DEFLECTONS, WAS CAUSED TO A LARGE EXTENT BY TRANSVERSE CRACKING OF SLABS. AT THE CONCLUSION OF THE TEST TRAFFIC, THE SLABS OF COMPOSITE BRIDGES WERE IN EXCELLENT CONDITION; THOSE OF NONCOMPOSITE BRIDGES WERE IN A MODERATE TO ADVANCED STATE OF DETERIORATION. THE POTENTIAL SUPERIORITY OF COMPOSITE BRIDGES WAS CLEARLY DEMONSTRATED. THERE WAS A MARKED DIFFERENCE BETWEEN THE CRACKING OF THE PRESTRESSED CONCRETE BEAMS POST-TENSIONED WITH PARALLEL WIRE CABLES AND PRE-TENSIONED WITH SEVEN WIRE STRANDS. IN THE BEAMS STRESSED WITH PARALLEL WIRE CABLES, SEVERE TENSILE CRACKING CHANGED RADICALLY THE RESPONSE OF THE BEAMS TO LOADING. THE CRACKING OF BEAMS WITH SEVEN WIRE STRAND CAUSED PRACTICALLY NO CHANGE IN THE RESPONSE OF BEAMS TO LOADING. BY THE END OF REGULAR TEST TRAFFIC ONE OR MORE FATIGUE CRACKS WERE FOUND IN ALL STEEL BRIDGES WITH PARTIAL LENGTH COVER PLATES. IN BOTH REINFORCED CONCRETE BRIDGES DESIGNED FOR A TOTAL STRESS OF 40,000 PSI, TWO BARS BROKE IN THE EXTERIOR BEAM AFTER A TOTAL OF APPROXIMATELY 730,000 STRESS CYCLES. IN PRESTRESSED CONCRETE BEAMS SUBJECTED TO TENSILE STRESSES LOWER THAN THE MODULUS OF RUPTURE OF CONCRETE SOME FATIGUE CRACKING OF CONCRETE WAS DETECTED DURING THE PERIOD OF TEST TRAFFIC. RESEARCH RESULTS LED TO THE OPINION OF THE BRIDGE PANEL THAT CONSIDERATION SHOULD BE GIVEN TO THE FOLLOWING POSSIBLE CHANGES IN DESIGN PRACTICES: (1) ALLOWANCE OF TENSILE STRESSES IN CONCRETE OF PRESTRESSED CONCRETE BEAMS PRE-TENSIONED WITH STRAND, (2) ALLOWANCE OF HIGHER DESIGN STRESSES IN THE STEEL BEAMS OF COMPOSITE BRIDGES, AND (3) MODIFICATION OF THE CRITERIA FOR DETERMINATION OF THE MINIMUM LENGTH OF PARTIAL LENGTH COVER PLATES.
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Supplemental Notes:
- pp 97-101 Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
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Corporate Authors:
Highway Research Board
2101 Constitution Avenue, NW
Washington, DC 20418 500 Fifth Street, NW
Washington, DC United States 20001 -
Authors:
- Viest, Ivan M
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Discussers:
- Erickson, E L
- Church, A C
- Marmelstein, C A
- Hewitt, H
- Friberg, B F
- Fenves, G L
- Thompson, W E
- Kahl, W R
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Conference:
- Highway Research Board Conference on the AASHO Road Test
- Location: St Louis MO, United States
- Date: 1962-5-16 to 1962-5-18
- Publication Date: 1962
Media Info
- Monograph Title: THE AASHO ROAD TEST - PROCEEDINGS OF A CONFERENCE HELD MAY 16-18, 1962, ST. LOUIS, MISSOURI
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Serial:
- Highway Research Board Special Report
- Issue Number: 73
- Publisher: Highway Research Board
Subject/Index Terms
- TRT Terms: Beams; Composite structures; Deflection; Fatigue (Physiological condition); Highway bridges; Metal bridges; Posttensioning; Prestressed concrete; Prestressing; Pretensioning; Reinforced concrete bridges; Slabs; Steel bridges; Stiffness; Tension; Transverse cracking
- Identifier Terms: AASHO Road Test
- Uncontrolled Terms: Tensile stress
- Old TRIS Terms: Overstressed zones; Test results
- Subject Areas: Bridges and other structures; Highways;
Filing Info
- Accession Number: 00209222
- Record Type: Publication
- Files: TRIS, TRB
- Created Date: Aug 26 1970 12:00AM