DEFICIENCY POINT METHOD FOR EXISTING BRIDGE EVALUATION

J. Vičan, P. Koteš a J. Slavík

University of ŽilinaFaculty of Civil Engineering

Department of Structures and Bridges

INTRODUCTION

At present, there are 2 281 railway bridges and 7 444 road bridges (without motorway bridges) in Slovakia, from which more than 20 % have not satisfactory loading capacities and about 2,5 % of all bridges are in critical technical condition.

From the viewpoint of aforesaid and in accordance with experience of the most developed European countries, there is a need to apply complex system approach and create the computer - aided Bridge management system based on the more sophisticated bridge evaluation.

RELIABILITY-BASED EVALUATION OF EXISTING BRIDGES

– Primary parameters:• Bridge loading capacity (LLRF) respecting actual technical bridge condition,• Bridge spatial arrangement (on bridge and under bridge

structure),• Bridge age or its remaining lifetime.

– Secondary parameters:• Parameter of road traffic intensity replacing bridge categorization according to road classification • Parameter of the bridge length underlining bridge significance from the building and economical viewpoint.

BRIDGE EVALUATION USING DEFICIENCY POINTS METHOD

Proposed method of Deficiency points respects following basic effects:

• Actual bridge loading capacity (BLC),• Actual bridge technical condition (BTC),• Actual bridge deck width (BW),• Actual vertical bridge clearance over and under the

observed bridge (BH),• Actual bridge age and its planned remaining lifetime

(BA).

Secondary parameters:

• Parameter of the road traffic intensity • Parameter of the bridge length

taking into account bridge significance from the building and economical viewpoint

Global number of deficiency points should be determined according following equation:

DP = WLC BLC + WTC BTC + WW BW + WH BH + WA BA

while DP Є 0,100

Influence of particular parameters is taken into account by weight factors:

WLC +WTC + WW +WH +WA = 100,

whereBLC is the number of deficiency points due to actual bridge loading capacity,

BTC is the number of deficiency points taking actual technical condition into account,BW is the number of deficiency points allowing for actual bridge deck width, BH is the number of deficiency points allowing for actual bridge vertical clearance over and under the bridge observed,BA is the number of deficiency points from the bridge age viewpoint,Wj are the weighting factors of individual evaluation parameters from the viewpoint of their influence on the complex bridge evaluation.

Influence of bridge loading capacity

1nmaxLC T T L L

max

LLRF LLRFB W K W K

LLRF

While BLC > 0 and

LLRFmax is the maximum characteristic value of the bridge loading capacity, LLRF is the actual value of the bridge loading capacity, WT is the weight factor of transport intensity influence,

WL is the weight factor of bridge length influence, n1 is the exponent allowing for category of communication.

Loading capacity is the basic evaluation parameter of the existing bridge reliability.

The loading capacity can be characterized as the relative member design resistance expressed in the design load effects of the standard load model

(1)/

n-1

d rs,Sd,i Sdi 1

LLRF R E E

where Rd is the design resistance of the bridge loading capacity limiting

member ESd are the design load effects of the standard load model o are design values of the other load effects affecting the bridge in combination with traffic load.

1

rs,Sd,i

1

En

i

WT + WL = 1,0

KT is the factor taking into account influence of transport intensity

ADI is average daily transport intensity on the bridge,ADTI is average daily intensity of truck transport on the observed bridge,max ADI is the maximum daily transport intensity in frame of evaluated region,n1, n2 are factors allowing for influence of automobile or truck transport 0 < n1 < 1,0 a 0< n2 < 1,0.

ADI ADTI ADTIT 1 2max ADI max ADI

K n n

KL is the coefficient allowing for bridge length effect

LL

L,max

BK

B

where BL is the bridge length, BL,max is the maximum bridge length in frame of evaluated region.

Influence of bridge technical condition

while BTC 0 and

TC is the actual evaluation of existing bridge technical

condition.

The given formulae is valid for road bridges, whose technical condition is classified into 7 classes.

( ) 1n

TC T T L L

7 TCB 1 W K W K

4

æ ö- ÷ç= - +÷ç ÷÷çè ø

Influence of bridge spatial arrangement

Effect of bridge deck width

1n

W T T L L

SW WB W K W K

SW

while BW > 0 and

SW is the standard value of bridge deck width, W is the actual value of bridge deck width.

Influence of bridge vertical clearance can be taken into account by following formulae:

1n

H U O T T L LB 0,5(H H ) W K W K

while BH > 0 and

HO is an influence of bridge vertical overclearence on the observed bridge, HU is an influence of bridge vertical underclearence of the observed bridge.

Influence of bridge vertical overclearence of the observed bridge

O OO

O

SH HH

SH

while HO > 0 and

SHO is the standard value of the vertical overclearence on the observed bridge,HO is the actual value of this parameter on the observed bridge.SHO = 6.0 m for railway communication, SHO = 4.80 m for roads of I. and II. category,SHO = 4.50 m for roads of III. category,SHO = 4.20 for local communications.

U UU

U

SH HH

SH

Influence of vertical underclearence of the observed bridge

while HU > 0 andSHU is the standard value of the bridge vertical underclearence of the observed bridge,HU is the actual value of this parameterSHU = 6.0 m over railway communication, SHU = 4.80 m over roads of I. and II. category,SHU = 4.50 m over roads of III. category,SHU = 4.20 over local communications, SHU = 0.50 over rivers.

Influence of bridge age

1nDA T T L L

D

RC T REB 1 W K W K

T

while BA > 0 and

TD is the design bridge lifetime in years,TD = 100 years,RC is year of bridge construction or reconstruction,RE is year of the bridge evaluation.

Váhové faktory

- Vplyv zaťažiteľnosti WLC = 30

- Vplyv technického stavu WTC = 45

- Vplyv šírkového usporiadania na moste WW = 10

- Vplyv výškového usporiadania na moste a pod mostom WH = 5

- Vplyv veku mosta WA = 10

- Vplyv intenzity dopravy WT = 0,8

- Vplyv dĺžky premostenia WL= 0,2

- Koeficient vplyvu intenzity dopravy n1 = 0,5

- Koeficient vplyvu nákladnej cestnej dopravy n2 = 1,0

- Koeficient vplyvu osobnej cestnej dopravy n3 = 1,0

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Thanks for your attention