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This study developed an optimal structural system for the hybrid cable-stayed bridge expected to have a durable lifetime of 200 years and of which major structural members are made of ultra high performance concrete (UHPC) with 200 MPa-class compressive strength. This innovative cable-stayed bridge system makes it possible to reduce each of the construction and maintenance costs by 20% compared to the conventional concrete cable-stayed bridge by improving significantly the weight and durability of the bridge. Therefore, detail design is carried out considering a real 800 m cable-stayed bridge and the optimal structure of the hybrid cable-stayed bridge is proposed and verified.
This paper presents highly efficient cable erection equipments and methods related to the construction of super-long-span bridges, construction technology of high towers and, technology for offshore foundations currently developed through a R&D on accelerated and cost-saving construction technology for long-span cable bridges to secure our international competitiveness. In the field of cable erection technology, AS and PPWS equipments for highly efficient erection of cable longer than 2000 m, world-class clamping bolt tensioning equipment and shape control system for super-long cable are under development. The technologies developed in the domain of construction of towers are tapered slip form system for the construction of 400 m high tower, shape and erection precision control of elevated tower and, lightweight and modular formwork for slip form system. In the domain of foundation construction, remote controlled survey equipment and analysis system for water-depth of 100 m and depth of 50 m, prediction and evaluation technology of optimal load carrying capacity and settlement complying with international standard and, highly efficient hybrid foundation construction technology suitable for ground acceleration of 0.5 g and deep soft soil are currently developed.
Slip-form system constitutes the latest technology for the erection of elevated concrete pylons. This paper investigates the design of slip-form system applying BIM technology for the efficient development of the slip-form system. The considered pylon has a height of 10 m and presents the rectangular hollow section generally adopted in cable-supported bridges. The slip-form was thus designed to accommodate the tapered cross-section and changing thickness considering the continuous placing of concrete. In addition, the safety of the system was examined with regard to the various loads applied on the slip form along the construction. The design results could be verified visually through BIM and the applicability of the designed slip-form was validated in advance through virtual assembly and construction.
Ultra-high performance concrete (UHPC) is featured by a
compressive strength 5 times higher than that of ordinary concrete and by a
high durability owing to the control of the chloride penetration speed by its
dense structure. The high strength characteristics of UHPC offer numerous advantages
like the reduction of the quantities of cables and foundations by the design of
a lightweight superstructure in the case of the long-span bridge preserving its
structural performance through axial forces and structures governed by
compression. This study conducted the conceptual design of a hybrid cable-stayed
bridge with central span of 1000 m and exploiting 200 MPa-class UHPC. The
economic efficiency of the conceptual design results of the hybrid cable-stayed
bridge with central span of 1000 m and of Sutong Bridge, the longest
cable-stayed bridge in the world, was analyzed.
Since high-speed railway bridges are subjected to cyclic
loading by the continuous wheel loads traveling at high speed and regular
spacing, their dynamic behavior is of extreme importance and has significant
influence on the riding safety of the trains. To secure the
riding safety of the trains, advanced railway countries have limited the
vertical acceleration of the bridge slab below critical values at specific
frequency domains. Since these limitations of the vertical acceleration
constitute the most important factors in securing the dynamic safety of the
bridges, these countries have opted for a conservative approach. However, the
Korean specifications limit only the size of the peak acceleration without
considering the frequency domain, which impede significantly rational
evaluation of the high-speed railway bridges in Korea. In addition, the
evaluation of the acceleration without consideration of the frequency domain is
the cause of disagreement between the dynamic analysis and measurement results.
This study conducts field monitoring and dynamic analysis on high-speed railway
bridges to gather the acceleration signals and compare them. Significant
difference in the size of the vertical acceleration was observed between the
measured and dynamic analysis accelerations when discarding the frequency
domain as done in the current specifications. The comparison of the
accelerations considering only low frequencies below 30 Hz showed that the
dynamic analysis reflected accurately the measured vertical acceleration.
The design live load of
railway is divided into common railway and high-speed railway separately inKorea.
Accordingly, the Korean design specification of railway specifies the impact
factor for common railway and high-speed railway respectively. The impact
factor for high-speed railway is based on Eurocode. Since the impact factor
criteria inKoreawere established by adopting those of the Eurocode and without dedicated
investigation relying on research results reflecting the domestic
circumstances, thorough examination should be implemented on these criteria.
Therefore the evaluation of impact factor based on field tests is required.
Both dynamic and static vertical displacements are necessary to compute the
impact factor. The dynamic response can be obtained from the measurement of
deflection of the bridge slab crossed by the firstKoreahigh-speed train (KTX, Korea
Train eXpress) running at high-speed. The main difficulties encountered are in
obtaining static response because static response corresponds to the response
of the bridge when the train remains immobile on the bridge or crosses the
bridge at speed slower than5 km/hr. This study
introduces the static response derived by applying the moving average method on
the dynamic response signal. To that goal, field measurements was conducted
under train speeds of5 km/hr and ranging
from100 km/hr to300 km/hr
on Yeonjae Bridge located in the trial section of the Gyeonbu High-Speed
Railway Line before its opening. The validity of the application of the moving
average method is verified from comparison of measured static response and
derived static response by moving average method. Moreover, evaluation is
conducted on the impact factor computed for a bridge crossed by the KTX train
running at operational speed.