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Suspended monorail transportation (SMT) plays an important role in alleviating the urban traffic pressure, and its vehicle–bridge dynamic features are significantly different from those of the traditional railway. To grasp the coupled vibration features of suspended monorail train–bridge system (SMTBS), this paper presents a comprehensive experimental investigation on the vehicle–bridge vibrational responses under different operating conditions. First, based on the Chengdu SMT test line in China, a full-scale field measurement of the coupled vibration responses of the SMTBS is elaborately conducted under constant speed conditions. Then, the vibrational responses of the SMTBS are analyzed in the time and frequency domains to reveal its coupled vibration features and vibration transmission characteristics. Further, considering an extreme train operating condition, the vibrational responses of the SMTBS are tested and analyzed under train emergency braking; and the vibration features of the vehicle and bridge are examined for emergency braking, along with several key indexes evaluated for the train braking performance. Results show that the vibrational accelerations transmitted from the frame to the center pin and then to the carbody will be significantly decreased in turn, and the vibrational dominant frequencies of the bogie, center pin, and carbody mainly fall with 0–100 Hz, 0–50 Hz, and 0–20 Hz, respectively. Under moving train loads, the box beam produces plentiful high-frequency vibrations and the vibrations transmitted from the driving track to the top plate are drastically reduced. The train braking significantly intensifies the car-body longitudinal vibration; however, it has small influences on the car-body vertical and lateral vibrations. [ABSTRACT FROM AUTHOR]

The Jinsha River rail–road double-deck arch bridge (bridge designed to 250 km/h) of the Chengdu–Guiyang high-speed railway (HSR) (designed to 350 km/h) is a complex system with a novel structure in China. The upper deck carries a four-track railway while the lower deck carries a six-lane urban expressway, with a height difference of 32 m. The bridge is located in the mountainous river reach of the city of Yibin. The 336 m main span adopts a high-pier, rigid steel frame, parallel tied-arch structure, built using cantilevers and temporary stay cables with the cable crane method. The 116 m and 120 m side-arches are reinforced concrete, simply-supported, basket-lifting tied-arches built by the mass cast in situ method. The rare layered structure gathers different arch types (top-bared, bottom-bared and half-through arches) into one bridge, which brought significant challenges to its design and construction. Other innovative solutions included flexible hangers passing through rigid hangers for the layered stiffening decks, ultra-high-performance concrete for the steel orthotropic deck road pavement and the use of boat shipments to overcome the scarce availability of flat land at the site. This paper describes some of the salient design and construction challenges of this landmark structure, the world's first double-deck HSR arch bridge. [ABSTRACT FROM AUTHOR]