Abstract
A girder depth is the critical parameter for rapid construction of bridge and clearance limitation in urban area such as high-density residential district. A standard post-tensioned I-shaped concrete girder usually demands relatively higher girder depth in order to retain sufficient moment arm between compressive and tensile fiber. To elaborate this issue, a small rectangular hollowed section can be used as a replacement of I-shaped standard girder. This small post-tensioned concrete box girder allows more flexible girder depth adjustment rather than standard I-shaped posttensioned girder plus additional torsion resistance benefits of closed section. A 30 m long, 1.7 m high and 3.63 m wide actual small post-tensioned concrete box girder is designed. A laboratory test was performed for its static behaviors by applying 6400 kN amount of load in the form of 4-point bending test. The load-deflection curve and crack patterns at different loading stage are recorded. In addition, to extract the dynamic characteristics, natural frequency and damping ratio of this girder, several forced vibration tests using oscillator are carried out with varying operational frequency. Nonlinear finite element analysis of this 4-point bending test under monotonic static load is discussed with the aid of concrete damaged plasticity using ABAQUS program. Finally, a series of modal dynamic analyses of different span length and girder depth of small post-tensioned girder bridge is performed in order to validate the applicability to railway bridges and compared to the UIC design criteria in the form of time dependent dynamic responses such as deflection, acceleration and end rotation.
Highlights
Since pre-stressed concrete beam has been applied in various civil infrastructures starting from 1960s, many sorts of pre-stressed concrete (PSC) girder have been developed and applied as a main flexural member for highway/railroad bridges around the world
The main advantages of this PSC girder is an ease of factory-manufacture and fabrication resulting into rapid construction, flexible choice of girder depth by adjusting initial jacking force aside from other advantages and disadvantages
Since the 3-girder railway bridge under high-speed train moving loads is concerned in this paper, one can extract this basic strain energy tuning parameters such as triple products of the min eigenvalue with associated eigenmode which is the 1st order bending motion and the frictional dynamic energy loss can be normalized with the term of damping ratio in the assumption of damage-free condition of the test specimen
Summary
Since pre-stressed concrete beam has been applied in various civil infrastructures starting from 1960s, many sorts of pre-stressed concrete (PSC) girder have been developed and applied as a main flexural member for highway/railroad bridges around the world. In case of railroad bridges, numerous type of prestressed-like girder such as Pre-flex girder (Portela et al 2011), steel-composite PSC girder (Rhee et al 2010), post-tensioned girder with readjustable jacking force, PSC girder with enhanced compression steel panel are being developed in worldwide Some of these girders are already used for highway/ railroad bridges but some of those are not and still are being tested in order to balance the paradox between structural safety and serviceability issues (Ju et al 2003, 2008; Rhee et al 2010). Bridge designer reluctantly selects a smaller cross-section with relatively large jacking force in order to meet this construction limit It may reproduce a resonance in a slender bridge superstructure with high longitudinal strength by car/train travel-induced forced vibration. The train load specification is based on KTX (Korean Train eXpress) which is identical to TGV in France
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call