In externally prestressed concrete bridge structures, the prestressed tendons are connected with prestressed concrete bridges by anchors and deviators, which are prone to be destroyed by the extremely complex stress concentration, resulting in prestress loss. Therefore, reasonable and safe design of anchors and deviators is very important for externally prestressed concrete bridges. In this paper, six inverted T-shaped specimens that represent the anchor blocks are tested to evaluate the effect of shear span–depth ratio and longitudinal reinforcement ratio on the shear behaviour of anchor blocks. The crack patterns, relative displacement, strain of steel and concrete, ultimate loads and failure modes are investigated. The experimental ultimate loads are compared with the calculated results from two design methods. Results indicate that the shear-friction model of AASHTO LRFD can predict the ultimate load very well when the shear span–depth ratio is less than 0·5. Meanwhile, in predicting the yielding load of the ties, the strut-and-tie model of ACI shows agreement with tested values at relatively large shear span–depth ratio of 0·57 and 0·93.
The backfill material for the underground pipe wall of Yellow River embankment was developed to avoid the high settlement and environmental damage caused by high filling and excavation. The interrelation between microstructure and compressive strength of the self-compacting foam backfill material with different water–binder ratios and density grades was investigated. The results indicated that the average pores size of the foam backfill material increased with increasing the water–binder ratio. Moreover, the compressive strength of the foam backfill material first increased and then decreased with continuously increasing the water–binder ratio. Based on the observation and the analysis of the computed tomography (CT) image, it can be found that the pore size of the foam backfill material decreased with the increment of the density grade. The overall findings demonstrated that the pore size and volume played an important role in affecting the performance of the foam backfill material used for the construction of the underground pipe wall of Yellow River embankment.
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