Yen,, B. T.

English

Lehigh University: Lehigh Preserve

Lehigh University
Lehigh Preserve
Fritz Laboratory Reports Civil and Environmental Engineering
1972
Final report on research projects on symmetrical
welded plate girders, December 1972.
B. T. Yen,
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Paper 1916.
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FINAL REPORT ON RESEARCH PROJECTS
ON SYMMETRICAL WELDED PLATE GIRDERS
by
B. T. Yen
FRITZ ENGINEERING
LABORATORY LIBRARY
December 1972
Fritz Engineering .Laboratory Report No. 327.10
{
327.10
INTRODUCTION
This report briefly surrnnarizes the objectives, research programs,
findings, implementation of results, and recorrnnended future research in
the area of welded plate girders. Specifically, the report is for
!lsYrrnnetrical-welded plate girders" (PennDOT Research Project 58-4) for
the reason that the results of separate efforts on "unsyrrnnetrical plate
girders" have been surrnnarized in another report(l) •
The research programs were carried out at the Fritz Engineering
Laboratory and Department of Civil Engineering, Lehigh University. The
programs included four projects under the direction of different research
workers. The project titles are:
Welded Plate Girders
Fritz Engineering Laboratory Project 251
Fatigue Strength of Welded Plate Girders
Fritz Engineering Laboratory Project 303
Longitudinally Stiffened Plate Girders
Fritz Engineering Laboratory Project 304
Welded Plate Girders - Design Recommendations
Fritz Engineering Laboratory Project 327
The time periods, sponsors,.and research workers of each of these projects
are sho,vn in Table 1.
-1-
327.10
Technical guidance to the projects were provided by the Sub-
committee on Welded Plate Girders - Lehigh University, Structural
Steel Committee of the Welding Research Council. The members of the
Subcommittee during these years' are listed in Table 2.
The support and encouragement of the sponsors and the Sub-
committee members are gratefully acknowledged.
OBJECTIVES AND PROGRAM
-2
The initial objectives of the research undertaking was to study
the web buckling strength of girder web panels, the influence of flange
restraint on the behavior of the web panels, and the static load-carrying
capacity of heavy-flange thin-web plate girders. As work progressed and
results accumulated, new objectives developed and corresponding research
programs were then established. These are summarized in Table 3.
The project "Welded Plate Girders" investigated theoretically and
experimentally the static strength of thin-web plate girders, and developed
design guidelines. Investigations were also made on the behavior of
transverse stiffeners on webs, of girder ends, and of partial length
coverplates. Design recommendations resulted in new specifications for
plate girders in buildings.
Preliminary application of project-recommended design rules for
building-girders to bridge-girders led to the project "Fatigue Strength of
Welded Plate Girders". Experimental studies were carried out together with
327.10
analysis of the influence of repeated lateral deflection of web on the
strength of plate girders.
-3
The influence of longitudinal stiffeners on the static behavior
and load-carrying. capacity of plate girders constituted another extension
of the initial project. Adoption of analytical methods of girder strength
prediction to girders with longitudinal stiffeners coupled with experi-
mental observations in providing background information for bridge girder
design.
The last project, "Welded Plate Girders - Design Reconunendations",
incorporated results of earlier studies for the formulation of design
reconunendations for bridge plate girders. Proof-testing of girders,
designed according to these rules, was a part of the program.
REsEARCH FINDINGS
Some of the more important results of the projects are the fol-
lowing:
1. Buckling of a web seldom occurs on steel plate girders. Web
buckling strength is not the strength of a plate girder, neither is the
girder load-carrying capacity a linear function of the \veb buckling
load (251.11 to 14 and 251.29).
2. The bending strength of a plate girder is determined from
the strength of an equivalent compression flange column which consists
327.10 -4
of the compression flange proper and an effective part of the web. The
resistance of the equivalent column against buckling (lateral,
torsional, and vertical towards web) is therefore of paramount importance
(251.19).
3. Girder panels under high shear have high post-buckling strength
if adequate transverse stiffeners or boundary supports are provided.
Tension fields develop, analogous to the tension diagonals of a Pratt
truss,and contribute to the shear strength (251.20).
4. The strength of girder panels subjected to both bending moment
and shearing is, in general, governed by either bending or shear alone.
,Interaction is significant only when bending and shearing stresses are both
high, for example, above 75 percent of yield point and 60 percent of
computed tension field stress, respectively (251.21, 251.29).
5. Methods for prediction of load-carrying capacity of plate
girders were verified by the results of testing large-size girders.
Girder strength can be expressed in terms of the yield point of the girder
material and geometrical parameters (251.19 to 21).
6. Transverse stiffeners can be cut short from the tension flange
to facilitate fabrication (25l.~).
7. A minimum area as well as a minimum rigidity are required of
transverse stiffeners to sustain the tension field action of web panels
(251.20).
327.10 -5
8. Ends of girders must be strong enough to anchor a tension
field action. One way of providing for such anchorage is to add an end
plate transverse to the girder web. The other is to place the stiffeners
for the last panel so as to prevent a tension field action from
developing (251.20, 251.29).
9. Stress transfer from a flange to a partial-length cover plate
is found to be gradual. No sudden increase of stress occurs at the
cutoff points (251.15).
10. Stress transfer in loading stiffeners is also found to be
gradual, being almost linear from the loading end to the opposite end
(251.15) •
11. Longitudinal stiffeners reduce lateral deflection of girder
web when compared to deflections of webs with only transverse stiffeners
(304.8~ 327.7).
12. In girders subjected to bending, a longitudinal stiffener at
one-fifth of the web depth from the compression flange effectively main-
tains the linear distribution of beam-theory flexural streses across the
girder depth (304.8).
13. The bending strength of the longitudinally stiffened girder
can be determined in fue same way as for transversely stiffened plate
girders if beam theory stresses are used (304.9).
327.10 -6
14. For girders subjected to high shear, longitudinal stiffeners
force separate tension fields in the subpanels. The shear strength of a
panel is the sum of the strength of the subpanels (304.8, 304.9).
15. Correlations were good between predicted and experimentally
observed load-carrying capacity of girders with longitudinal stiffeners
(304.9).
16. Longitudinal stiffeners must fulfill requirements of
rigidity, cross-sectional area, and width-to-thickness ratio so as to be
effective (304.9).
17. If repeated loads are applied to a girder, its web moves
repeatedly between two lateral positions and in synchronization with the
load (25l.26A, 303.10).
18. The consequence of severe lateral movement of web is the
possibility of fatigue cracks along the boundary of thin webs (251. 26A,
303,.10) • ,
19. The web plate bending stress ranges by lateral deflections were
found to correlate well with the number of load cycles at which a~acks
occurred (303.10).
20. A method was developed for estimating, from measured web
deflections, plate bending stresses at web panel boundaries. These
calculated stresses were in good agreement with stresses obtained from
measured strains (327.2).
327.10 -7
21. Longitudinally stiffeners reduce lateral deflection of web
and the possibility of fatigue cracks at web panel boundaries (327.7).
22. For plate girders with web thickness conformed to the
minimum requirements for highway bridges, the lateral deflections of web
were relatively small and no fatigue cracks were observed in these web
panels in the test girders of these projects (327.7).
These results have been presented in various reports. Table 4
lists the published and some unpublished reports of the projects.
IMPLEMENTATION
1. Based on the findings of the initial research project on welded
plate girders (251), design recommendations were formulated for plate
girders in buildi.ngs "(251. 23) and for the static strength design of bridge
girders (251.25).
The recommended limits on web slenderness ratio, web panel proportion,
stiffener size and rigidity, stiffener spacing, and flange proportioning
were all incorporated by the American Institite of Steel Construction in
°t °fo ° ° 1961(2)1 S spec1 1cat10ns S1nce .
2. From the results of studies on longitudinally stiffened girders
(304), on fatigue of plate girders (303), as well as on unsymmetrical plate
girders, design recommendations were derived for highway bridges by the
327.10
'load-factor design procedure(3). These recommendations have now been
adopted by the American Association of State Highway Officia1s(4) .
For the design of highway bridge girders using the allowable
stress approach, recommended rules are included in Fritz Engineering
Laboratory Report 327.6F, entitled "Design Recommendations for
Bridge Plate Girders". The submission of these proposed rules through
the Pennsylvania Department of Transportation to AASHO for adoption is
expecte-d.
RECOMMENDATIONS FOR FUTURE RESEARCH
-8
One of the results of these re~earch projects is the widespread
interest in plate girder strength in this country and abroad(5). Most of
these recent studies are refinements to the analyses by the projects
which are summarized here. Efforts may be made to incorporate the
refinements into detailed design rules.
More urgently needed for design purposes, thus recommended here,
include the following areas:
1. Strength of composite plate girders (not beams) with
and without transverse stiffeners.
2. Strength and behavior of haunched (straight and
curved) plate girders.
327.10 -9
3. Load-carrying capacity of ~orizontally curved plate
girders.
4. Application of available results from plate girder
studies to the analysis of box girders.
Work is in progress which covers parts of items 1 and 4 above.
Research pursuit in the direction of items 2 and 3 should be initiated.
Project Title Welded Plate
Girders
(251)
TABLE 1
Fatigue Strength of
Welded Plate Girders
(303)
Longitudinally
Stiffened Plate
Girders
(304)
Welded Plate Girders -
Design Recommendations
(327)
W
N
".
1----------- _._ _.._ _-_ _ " _- _.. _ _.._.....c_, • . --_.•, '-'-"" ---••----. _._ -- " •••.••_. - --'" .- -----1
Project
Period
February 1958-
July 1963
AugUst 1963-
July 1966
August 1963-
July 1966
August 1966-
September 1969
r----------+--------~------------~----------_t_-.---.-------------j
Sponsors Welding Research Council
American Institute of Steel Construction
U. S. Bureau of Public Roads
Pennsylvania Department of Highways (58-4)
Welding Research Council
American Iron & Steel
Institute (134)
U. S. Federal Highway
Administration
Pennsylvania Department
of Transportation
(58-4)
t----------+-------------------.------....-..---------------'---.-..-.---------'1
Other
Contributors
Association of .
American
Railroads
Fort Pitt
Bridge Co.
Great Lakes
Steel Corp.
R. C. Mahon Co.
!---·---------t--..-···--....·-···--·--·--I-------------,c----------t---------------i
Project
Personnel
L. S. Beedle L. S. Beedle L. S. Beedle L. S. Beedle
B. Thurlimann B. T. Yen T. V. Galambos B. T. Yen
K. Basler A. Ostapenko A. Ostapenko A. Ostapenko
B. '" Yen P. B. Cooper P. B. Cooper J. A. Mueller....
P. B. Cooper J. A. Mueller B. T. Yen J. A. Corrado I
t-'J. .A. Mueller J. A. Corrado D. J. Fielding J. S. Huang 0
H. S. Lew K. E. Dudley M. A. D'Apice P. J. Patterson
M. U. Taysi
J. S. Toh
.. .._---
327.10
TABLE 2
-11
Mem~ers of Subcommittee on Welded Plate Girders - Lehigh University,
Structural Steel Committee of The Welding Research Council
E. L. Erickson W. B. McLean
M. Denterman w. A. Milek
G. F. Fox N. W. Morgan
J. H. Adams T. A. Mowatt
A. Amirikian w. H. Munse
L. S. Beedle J. F. Oyler
Karl deVries E. o. Pau1et
L. H. Daniels E. Pisetzner
F. H. Dill E. J. Ruble
J. L. Durkee F. Sankey
E. R. Estes c. F. Schelley
J. A. Gilligan J. E. South
LaMotte Grover R. H. Stuchell
W. C. Hansell Bruno Thur1imann
K. H. Heilman Neil Van Eenam
T. R. Higgins J. Vasta
W. H. Jameson Ivan M. Viest
C. D. Jensen George Winter
Knut Jensen W. Spraragen
Bruce G. Johnston c. A. Zwiss1er
H. Juh1 C. F. Larson
R. L. Ketter
M. L. Hoeh1er
K. H. Koopman
George Lam
327.10 -12
TABLE 3
PROJECT OBJECTIVES AND RESEARCH PROGRAMS
Project Objectives Programs
Welded Plate
Girders
I 1. Survey knowledge of plate
girder behavior, stability
and load-carrying capacity.
2. Theoretical studies on
static strength of plate
girders.
3. Observation of static
behavior.
4. Development of design
guidelines.
1. Literature Survey.
12. Development of methods
for the prediction of
plate girder strength
in bending, shear, and
combined bending and
shear.
3. Testing of large-size
welded plate girders
under static loading.
4. Formulation of design
recommendations.
Observation of fatigue
behavior of web panels of
welded plate girders.
Analysis of influence of
repeated lateral deflection
of web on the strength of
plate girders.
1.
2.
2.
Fatigue
Strength of
Welded Plate
Girders
11. Testing of large-size
Ii welded plate girders
I under repeated loading.2 Development of method
I . for estimation of webIj boundary stresses andI fatigue strength of
I web panels.r--Lo-n-g-i-t-u-d-~-'n-a-l-l-y-f-l-.--Th-e-o-r-e-t-~-·c-a-l-s-t-u-d-i-e-s-o-n-s-t-a-t-~-'c- -l-.--D-ev-e-l-o-p-m-e-n-t--o-f-m-e--t-h-o-d-s-----l
Stiffened Plate strength of plate girders I for the prediction of
Girders with longitudinally load-carrying capacity
stiffeners. of girders under
Observation of static bending and shear.
behavior. 2. Testing of large-size
girders.
Welded Plate
Girders -
Design
Recommendations
Ij1.
2.
Development of Design Recom-
mendations considering both
static and fatigue strength
of plate girders.
Experimental verification
of recommended rules.
Formulation of desi.gn .
recommendations. I
Proof-testing of large- I
size welded plate girders
designed according to I
recommended rules. I
to
327.10
TABLE 4
A. LIST OF PUBLISHED REPORTS
251.2 B. Thurlimann
STRENGTH OF PLATE GIRDERS
Proc. AISC National Engineering Conference, April 1958
251.6 K. Basler and B. Thurlimann
PIATE GIRDER RESEARCH
Proc. AISC National Engineering Conference, April 1959
251.7 K. Basler and B. Thurlimann
BUCKLING TESTS ON PLATE GIRDERS
Preliminary Report, 6th Congress of IABSE, 1960
251.11 K. Basler, B. T. Yen, J. A. Mueller and B. Thurlimann
WEB BUCKLING TESTS ON WELDED PLATE GIRDERS
WRC Bulletin No. 64, September 1960
251.14
251.15 J. A. Mueller
STRESSES IN COVER PLATES AND BEARING STIFFENERS
WRC Bulletin No. 63, August 1960
251.16 K. Basler
.FURTHERTEST.$,:ON WELDED PLATE GIRDERS
l'roc. AISC''Nat'ional Engineering Conference, June 1960
251.18 K. Basler and B. Thurlimann
BUCKLING TESTS ON PLATE GIRDERS
Final Report, 6th Congress of IABSE, July 1960
251.19 K. Basler and B. Thurlimann
STRENGTH OF PLATE GIRDERS IN BENDING
Proc. ASCE, Vol. 87, ST6, August 1961
251.20 K. Basler
STRENGTH OF PLATE GIRDERS IN SHEAR
Proc. ASCE, Vol. 87, ST7, October 1961
-13
251.21 K. Basler
STRENGTH OF PLATE GIRDERS UNDER COMBINED BENDING AND SHEAR
Proc. ASCE, Vol. 87, ST7, October 1961
251.23 K. Basler
NEW PROVISIONS FOR PLATE GIRDER DESIGN
Proc. AISC National Engineering Conference, May 1961
--~_. - ~'---~-'-~--"-~ ....... --...• -,"......._-~ .. - ... _... _,..-_.. - . -~ -_. - _.
327.10 -14
251.25 B. T. Yen and K. Basler
STATIC CARRYING CAPACITY OF STEEL PLATE GIRDERS
HRB Proc., Vol. 41, 1962
251.26A B. T. Yen and P. B. Cooper
FATIGUE TESTS OF WELDED PlATE GIRDERS
.AWS Welding Journal, Vol. 42, No.6, June 1963
251.29 P. B. Cooper, H. S. Lew and B. T. Yen
WELDED CONSTRUCTIONAL ALLOY STEEL PlATE GIRDERS
Proc. ASCE, Vol. 90, ST1, February 1964
303.5 J. W. Fisher and B. T. Yen
Discussion on FLEXURAL FATIGUE TESTS OF PRESTRESSED
STEEL I-BEAMS by W. D. Reneker and C. E. Ekberg
Proc. ASCE, Vol. 90, ST4, August 1964
303.10 B. T. Yen and J. A. Mueller
FATIGUE TESTS OF LARGE-SIZE WELDED PlATE GIRDERS
WRC Bulletin No. 118, November 1966
304.8 M. A. D'Apice, D. J. Fielding and P. B. Cooper
STATIC TESTS ON LONGITUDINALLY STIFFENED PlATE GIRDERS
WRC Bulletin No. 117, October 1966 .
304.9 P. B. Cooper
SrRENGTH OF LONGITUDINALLY STIFFENED PLATE GIRDERS
Prac. ASCE, Vol. 93, ST4, April 1967
304.10 P. B•.Cooper .
~1HE CONTRIBUTION OF LONGITUDINAL STIFFENERS TO THE
'STATIC STRENGTH OF PLATE GIRDERS
.~ighway Research Record 167, 1967
327.2 J. A. Mueller and B. T. Yen
GIRDER WEB BOUNDARY STRESSES AND FATIGUE
WRC Bulletin No. 127, January 1968
327.7 P. J. Patterson, J. S. Huang, J. A. Corrado and B. T. Yen
FATIGUE AND STATIC TESTS OF TWO WELDED PLATE GIRDERS
WRC Bulletin No. 155, October 1970
327.9 A. Ostapenko, B. T. Yen and L. S. Beedle
RESEARCH ON PLATE GIRDERS AT LEHIGH UNIVERSITY
Final Report, 8th Congress of IABSE, September 1968
..
327.10
TABLE 4
B. LIST OF SOME PROJECT REPORTS
(not included in List A)
251.8 K. Basler
STRENGTH OF PLATE GIRDERS
October 1959
251.22 K. Basler
DESIGN RECOMMENDATIONS FOR PLATE GIRDERS
March 1961
251.30 L. S. Beedle and B. T. Yen
A FINAL REPORT ON PROJECT 251 - WELDED PLATE GIRDERS
December 1963
303.1 B. T. Yen
ON THE FATIGUE STRENGTH OF WELDED PLATE GIRDERS
September 1963
303.4 K. E. Dudley, J. A. Mueller and B. T. Yen
LATERAL WEB DEFLECTIONS OF WELDED TEST GIRDERS
June 1966
303 •13 B. T. Yen
A SUMMARY REPORT ON THE BEHAVIOR OF THIN-WEB PLATE
GIRDERS UNDER REPEATED LOADING
August 1966
304.6 P. B. Cooper
BENDING AND SHEAR STRENGTH OF LONGITUDINALLY STIFFENED
PLATE GIRDERS
September 1965
304.11 P. B. Cooper and A. Ostapenko
FINAL REPORT ON PROJECT 304, LONGITUDINALLY STIFFENED
PLATE GIRDERS
July 1966
327.4 J. S. Huang and B. T. Yen
STIFFENER REQUIREMENTS FOR PLATE GIRDERS
June 1968
-15
327.10
327.6F B. T. Yen
DESIGN RECOMMENDATIONS FOR BRIDGE PLATE GIRDERS
June 1972
REFERENCES
1. Ostapenko, A.
FINAL REPORT ON RESEARCH PROJECT "UNSYMMETRICAL PLATE
GIRDERS"
Fritz Engineering Laboratory Report No. 328.16, May 1972
2. AISC
SPECIFICATION FOR THE DESIGN, FABRICATION AND ERECTION OF
STRUCTURAL STEEL FOR BUILDINGS (with Commentary)
November 1961
3. Vincent, George S.
TENTATIVE CRITERIA FOR LOAD-FACTOR DESIGN OF STEEL
HIGHWAY BRIDGES
American Iron and Steel Institute, February 1968
4. AASHO
INTERIM SPECIFICATION, 1971
5. IABSE
SUMMARY REPORT, COLLOQUIM ON THE ULTIMATE RESISTANCE
OF PLATE GIRDERS WITH STIFFENED WEBS
April 1971
-16


Final report on research projects on symmetrical welded plate girders, December 1972.

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