PEFUODICA POLYT2CHSIC,A S2R. CIVIL E"","G. i,'OL. J.l. XO. 1. PP. 51-57 (1997,'
EXAMINATION IN STEEL USING
Depanment of Steel StruCTures Technical l'niyersity of
H-1521 Budapest, Hungary Received: June 1.:). 1995
Abstract
During 1994-1995 the of Steel Structures at the T~ech:lica] of Bu- dapest conducted a paTan1etrica} OE the effects of on faih\,ay bridges. T'he study was concentrated on supported bean:s. The \Vest European proposals Eurocode') on raihvay bridge construction \vere used as a basis for this study, The results of the study indicated that a part of the Eurocode proposals can be applied to Hungarian ralh;:ay Ho\ve\'er. further exanlination is required on cOEcinuous beams.
railway bridges. steel structures.
Introduction
In previous years, West European fatigue examinations on railway bridges were conducted using the UIe proposals on traffic types. During these studies, the ideal (UIe) train loads were replaced with other load types.
In this study, different ideal loads were used for improving the accuracy, for example, differentiation between passenger trains and carriage trains.
This differentiation of load types 2) depended upon the annual volume of traffic on the railway iines.
The use of the differentiated load types requires more accepted effects and lower clarity in the work. As a consequence, the UIe ideal load was used.
The following correction factor was included in the empirical analysis to compare the calculated stress with fatigue allowable stress [1] [2] :
(1)
1 Professor of Structural Engineering 2PhD Student
.j2 .::J. ?LATTH)' and R. J.4RA.\1.-1S!
where )\1: is a function of the span and traffic type
A2: is a factor to take account of the annual volume of traffic A3: is a factor to take account of the design life of the structure
)'4: is a factor to be applied when the structural element is loaded by more than one track
The A2, A3 and A4 factors, however, do not depend on load types or on the structure elements. Thus, Al is the most important variable, and is a function of normal stress (iT) or shear stress (T) (i.e. Al can be differentiated into A 10" and )q,). This study focussed on the two factors.
in Hungary
The previously mentioned Eurocode proposals for fatigue examination to be used in Hungary required answers for the following two questions:
Due to differences between VVest European and Hungarian load types, can the results of the calculation of in the 'West European pro- posals be used in Hungary?
Can the -vVest European proposals, which affirm
be used in Hungary ?
Referring to the first question, the proposal of Sander FORGO for railway traffic types was accepted, considering his study in traffic of the
Hungarian company [3]
To ansvv-er the second question.
this study.
raihvay v;ere used in
Factor
The calculation of Alu was conducted on the center points of 3, 5, 7,
la
and50 meter simply supported beams. The volume of traffic was 25 million tons per annum. As a result,
=
1 and the design life of the structure is 100 years (i.e.=
1). The structural element was loaded by one track (i.e. A"=
1). Therefore, A =During the study, the Standard S - IV curve (i.e. Wohler curve) and Palmgren Miner Cumulative damage calculation were used.
In the first step, influence diagrams were constructed for each load type (refer to Figs. 1 and 2), these influence diagrams were used to calculate stress range (6iTi) and the load cycles i) using the Reservoir method.
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Following this, the reference value of fatigue stress at two million cycles (!::::.o-e) was determined as :
1 I~) A 3 " '%"" '-0,1 A 3 06-L
. 31' \ I - ' - - - ' - ! 1\0-, ' n " ( j ) ' - ) 2 , 2 '.L-.J-D IV '~·D.o-,·n·· J ] 'ur , 2
1/ ' ,
if 2 J
The Eurocode proposal:
,:}/as then \i\,:,here
le' : is the stress range due to the [T
le
loadin the most unfavourable position for the member under consideration.
02 is the dynamic coefficient.
1.44
- - ; : : = - - -
+
0.82 ,0.82 ( 1
0- /'
-'-.. ;).::::
<
1is the dynamic coefficient for each service train type.
or ,1/ 0 -6 - ( ) q; = .u . e \ V
=
speed (m/s)= 1
+
0.5K=
K
, 0 - 1/)
I " .t)'P.
for L
<
20 m for L> 20 m(3)
(6)
As seen in Table 1, the results of )..10' in this study are similar to the Eu- rocode results, therefore, the Eurocode proposals can be used in Hungary.
Table 1 The volume of Ale,.
L Type I Type II Type In Type IV \!ix ECROCODE
3.0 1.63 1.61 1.39 2.2.9 1.68 1.36
,5.0 0.88 0.92 0,76 1.2 1.00 1.02
7.0 1.07 1.01 0.79 1.31 0.96 0.9-1
10.0 0.79 0.62 0.68 0.9:3 0.7.5 0.82
50.0 0 . .59 0,48 0 . .5.5 0.62 0.56 0.62
·54 P. PLATTHY c.nd R. JA.R..A.\1.A:\·j
Study on )\l, Factor
flYe was determined as:
fly = - - . 1
e
ifNe
The same method of calculation of .Ala- was used to calculate )'1,.
To contrast .Ala- with .A 1; , the following ratio was used:
(7)
( 0 \
0)
The results of this calculation are shown in Table 2. The volumes of a ratio are not similar to the Eurocode results, therefore, the Eurocode proposals cannot be used in Hungary.
Table :2 The volu!l1e of 0; rat.io
L [m] Type I Type II Type III IV :viix ECROCODE
:3.0 0.60 0.76 0.60 0.60 0.68 1.00
.5.0 0.98 1.28 1.03 0.86 1.06 1.00
7.0 1.20 ~ .-tl 1.48 l. 1.-12 l.00
10.0 1.16 1.87 LE 1.25 1,48 1.00
50.0 1.61 1.90 1.6, 1.52 1.66 1.00
Since the maximuIT: moment and ll2.xinlUm shear force in continuous , oeams are In the same future exanlination \;{iil be carried this study.
Conclusions
The results of this study show that the Eurocode proposals for moment in- duced fatigue in railway steel bridges can be used in Hungary, but the pro- posals for shear cheking fatigue as seen in Eg. (7) cannot be used there.
However, attention is required on continuous beams as the Eurocode pro- posals have not yet been affirmed in this area, this is especially important in welded connections, where normal stress has an interaction with shear stress.
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·57
References
1. Eurocode Eiriwirkungen aUI Tragwerke iVorschlag Version: July 1991.
2. PLATTHY, P. (1994): .\ew Hungarian Standards for Railway Bridges. XVII. Czech and Slovak: Int .. Conj. on Steel Struci1lres. Proceedings. I. pp. 399-403.
3. FORGO. S. (199.5): A vaslni acelhidak f~.radasa of the Steel Railway Bridges).
) .
Sinek yilaga. \~ol. X):='{\·III. pp. 179-188
J'-\R.~.:,jA\L R. (199.5): of Fatigue in
\-. TOTesrnechani!cci S:::erniruiriu711. ~liskolc. pp. 57-68 cs a faradl valarnilH a faraszto iizemi
Crack and the 'Value of the
