Page 31 - สำนักบำรุงทางรายงานประจำปี 2563

AMAGE INSPECTION,
STRUCTURAL EVALUATION
AND REHABILITATION OF
A BALANCED CANTILEVER
BRIDGE WITH CENTER HINGES

Bridge inspection and evaluation of the and will have no further effect on the movement of
Phra Pinklao Bridge, having structural configuration the hinge bearings in the future after replacement.
of a balanced cantilever bridge with center hinges, Responses of the bridge structure
is carried out in order to determine appropriate and identification of any structural damages and
measures for bridge rehabilitation. The bridge deficiency are examined by employing diagnostic
structure is a 3-span, continuous prestressed load testing under predetermined loading to gain
concrete box girder with a total length of 280 physical insight into load-carrying behaviors
meter and a width of 26.6 meter supporting regarding structural deterioration and susceptible
6 traffic lanes. The investigation tasks include damages that may occur due to bridge aging and
1) bridge visual inspection, 2) measurement of center hinge deficiency. Nine 3-axle domestic
bridge alignment and profile, and joint movements, trucks with the predetermined gross weight of 245
3) bridge load test and behaviors measurement, kN per truck are employed as test load. Based on
4) structural analysis and load-rating evaluation, the test results, the overall structural responses
and 5) appropriate bridge rehabilitation plan. are in normal conditions. No indication regarding สํะพื่านัสํมเด็จึพื่รุะป็ิ่นัเกล้า
Based on the results of bridge inspection, any loss of load-carrying capacities or structural เกิดความเสํียหายบํรุิเวณกงกลางสํะพื่านั
ึ
�
structural damages of the center hinge bearings in deficiency can be observed. Upon removal of the Hinge Bearing ที�ทําหนั�าที�รุับํแรุงเฉือนั
a critical state are reported. The damages include test load (unloading), elastic recovery of strains and ชํารุุดเสํียหาย เนัื�องจึากการุหดต้ัวและ
permanent deformation of stayed plates and plunger displacements of the box girder can be illustrated. การุคืบํต้ัวข่องคอนักรุีต้อันัทําให�ความ
edges of the hinge bearings causing the bearing No permanent deformation of the bridge structure
movement to be restrained and direct impact on is reported. สํามารุถึในัการุใช้งานัลดลง จึําเป็็นัต้้อง
serviceability and load-carrying behaviors of the A three-dimensional finite element model ทําการุซึ่่อมแซึ่มแก้ไข่ป็รุับํป็รุุง Hinge
bridge structure. According to the measurement is employed in the structural analysis of the bridge Bearing ให้สํามารุถึรุับํแรุงได้ต้ามที�ออกแบํบํ
results of bridge geometric surveying, no structure. The finite element model is verified and ไว้ เพื่่�อให้สํามารุถึใช้งานัได้ต้ามป็กต้ิและ
abnormalities of bridge alignment and profile of updated on the basis of the measurement results ป็ลอดภัย
the existing structure are found. In conjunction employing a sensitivity-based finite element model
with the results obtained on creep and shrinkage updating technique. The results of load-rating
deformation analysis of the bridge structure, it is evaluation yielding sufficient load-carrying capacities
anticipated that the accumulative movement of of the existing box girder are reported.
the bridge components is likely due to creep and According to the investigation findings,
shrinkage of concrete material under long-term it is anticipated that appropriate implementation
DRR
compression effect. It is estimated that under the of the planar hinge bearing concept would yield a maintenance
current conditions of the existing structure, the most suitable and effective method for the center
bridge creep nearly approaches a constant state hinge bearing replacement of the bridge structure. 31