Presentation on rating & strengthening of bridges @ jntu hyd by raghavendra
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JNTU COLLEGE OF ENGINEERING, ANANTAPUR. PRESENTATION BY…. R.RAGHAVENDRA K.MADHAVULU III/IV B.Tech, Civil III/IV B.Tech, Civil
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Rating is evaluation of safe load carrying capacity of existing bridges. There are different systems for rating in the world. In India mainly analytical, load testing and correlation methods are followed. Rating has reduced economic burden on authorities for some time. Rating has provided people with direction for follow up actions such as repairs, strengthening rehabilitation. It is becoming preferable, both environmentally and economically to upgrade bridges rather than to demolish and rebuild them. Deterioration of bridges wear from environmental influences and from traffic loads require rehabilitation and renewal programs to maintain even current service levels on the bridge infrastructure network. Demands for high durability, longer service life, reduced maintenance cost and cost/performance optimized. This paper deals with the rating of bridges and different methods of strengthening with its world wide applications.
Transcript of Presentation on rating & strengthening of bridges @ jntu hyd by raghavendra
JNTU COLLEGE OF ENGINEERING, ANANTAPUR. PRESENTATION BY….
R.RAGHAVENDRA K.MADHAVULU III/IV B.Tech, Civil III/IV B.Tech, Civil
CONTENTS :1. SCOPE2. RATING METHODOLOGY3. PROCEDURE FOR RATING4. Strengthening5. POSTING6. CONCLUSION7. REFERENCES
SCOPE : INTRODUCTION…
RATING…
NECESSITY OF RATING…
LOADS FOR RATING…
Poor quality * DEAD LOAD
* LIVE LOAD
* IMPACT
RATING METHODOLOGY:
LOADS
STRESSES
FATIGUE
DESIGN PHILOSOPHY
GLOBAL PRACTICES
RATIING SYSTEM
ANALYTICAL METHOD
CORRELATION METHOD
LOAD TEST METHOD
ANALYTICAL METHOD It is applicable when as built or contract drawings and
specifications followed are available or when such drawings can be
prepared by site measurements to an acceptable level of accuracy.
CORRELATION METHOD This method is adopted when the safe carrying capacity of
structure can be ascertained by correlating the sectional details of the
structure.DIFFERENT GRAPHS USED IN METHOD
LOAD TEST METHOD It is applicable when no construction drawings and specification
originally followed are available or when such details are not possible to
be obtained an site. PROOF TEST
FAILURE TEST
VEHICLES FOR TESTING
Test vehicles are chosen such that
they are the next heaviest vehicle than
the predominant heavy load presently
passing over the bridge.
Study all available data, drawing, etc.
Detailed field or lab investigation
Compute section capacity in moment and shear at selected location
Assess reduction factor ()
Compute Mcap and Vcap
Compute effect of all loads other than live loads at
selected
Compute MLL = Mcap – MDL VLL = Vcap – VDL At
selected locations
Compute maximum LL moment and shear at
selected locations
CompareMLL ~ MLL
VLL ~ VLL
Bridge rated For corresponding IRC
standard Live Loading
• Mcap : Moment resisting
capacity of selected section.
• Vcap : Shear resisting
capacity at selected section.
• MDL and VDL : Moment and
shear of all loads other than
live loads at selected section.
• MLL and VLL : Net resisting
capacity minus effect due to
all loads other than live loads.
• MLL and VLL : maximum
possible effect (moment and
hear) including impact effect.
Where
SPACING AND NUMBER OF VEHILES
Closer spacing of vehicles in urban areas is a frequent possibility.
Urban traffic is mixed and slow as against the heavy and fast traffic
for which the rating is proposed and high impact percentage.
SINGLE LANE BRIDGE
SPACING
Standard and heavy trucks 30 Mt
Articulated vehicles 18.5Mt
DOUBLE LANE BRIDGE
Vehicle arrangement
Double lane bridges are
those with carriageway
width above 5.5m and
up to 7.5 m for all spans.
PROCEDURE FOR RATING CALCULATION OF SAFE AXEL LOAD
RATING OF BRIDGES (IRC S.P.67)
CLASS FOR MORE THAN 6
WHEELERSMAX. SINGLE AXLE LOAD
30 R 14.0 t
16.0 t
17.5 t
19.0 t
20.0 t
40 R
50 R
60 R
70 R
CLASS FOUR WHEELERSMAX. SINGLE AXLE LOAD
SIX WHEELERS MAX. SINGLE AXLE LOAD
3 R 1.1 t 1.0 t
5 R 3.4 t 2.2 t
9 R 5.8 t 3.5 t
12 R 7.5 t 4.8 t
18 R 10.0 t 7.6 t
24 R 12.0 t 8.5 t
STRENGTHENING : ADDITION OF UNSTRESSED OR PRE-SRTESSED STEEL
INSTALLATION OF EXTERNAL PRE-STRESSED
REINFORCEMENT
BONDED REINFORCEMENT
INCREASE OF THE CONCRETE CROSS-SECTION
CARBODUR CFRP PLATE SYSTEMS IT CONSIST OF CARBON FIBER
E – Modulus N/mm2
Tensile Strength N/mm2
Elongation @ Break
Carbodur S 165’000 2’800 > 1.7
Carbodur M 210’000 2’800 > 1.35
Carbodur H 300’000 1’350 > 0.45
Material properties of carbodur CFRP plates
BONDING OF CFRP PLATES :
Test Specimen Fbr KN Ybr mm br Specimen 1 Curing without oscillation
161 70 6.61
Specimen 4Curing with oscillation
176 75 6.55
Test results
POSTING Posting is a method to restrict the loading on the existing
bridge.
TRAFFIC RESTRICTIONS 8 SPEED RESTRICTION 8 FOOT PATH LOADING
8 GEOMETRIC RESTRICTIION
ALTERNATIVES TO POSTING 8 FRAME BARRIERS 8 FREQUENT INSPECTION
8 LANE LIMITS 8 REPAIR
CONDITION POSTING
RATING > LOAD NOT REQUIRED
RATING < LOAD REQUIRED
POSTING SIGN
Regulatory signsare installed on eitherSide of bridge
ENFORCEMENT
Restrictions inrespect of Max. load, Geometrical limits, Speed for safety of brides.
CONCLUSION :• Rating helps to determine the safe carrying capacity of
bridges, thus the structure can be made safe for use.
• Accidents can be avoided due to collapse of the old bridges which have undergone deterioration by posting.
• Follow-up actions can be taken according the rating of bridge such as and this current or future loading on the bridge repairs strengthening or demolition of old bridge and construction of new bridge.
REFERENCES :
* Bridge Engineering –
D.R.Phatak
* WWW.GOOGLE.COM
* WWW.ALTAVISTA.COM
* Public works department, Nasik
* Indian Road congress, Special
Publication 37
R.RAGHAVENDRA
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