To provide an effective basis and reference for applications of prestressed concrete thin‐slab beams after a bridge fire, methods and principles of fire‐resistant design, repair, and reinforcement of such beams were discussed. Taking a simple supported and continuous girder bridge of an expressway in service as a sample, appearance testing and nondestructive testing of the internal structure were carried out. Four representative full‐scale prestressed concrete beams were selected. Through the comparative test of the ultimate bearing capacity of such beams, the laws of the deflection deformation, strain distribution, crack formation, and crack development were obtained. By combining with the finite element simulation and theoretical analysis, the ultimate bearing capacity, complex mechanical characteristics, and breakage feature and failure mechanism of such beams were studied. It was indicated by the results the following: (1) Prestress loss will cause height reduction of the concrete shear zone, which is one of the main reasons why the bending‐shearing failure of such beams happened before the pure bending failure. (2) Under certain operating loads, brittle fracture is more likely to occur on the bottom surface of such beams when directly exposed to fire. (3) The bursting and spalling depth of concrete after being exposed to fire can be used as the characteristic parameters for the rapid identification of the bottom surface of such after‐fire beams.
27 September 2023 in Structural Engineering International
This groundbreaking study conducts the first-ever field push test on anchor bolts in steel–UHPC composite pavement in China, providing researchers with the opportunity to obtain the true mechanical performance of the anchor bolts after more than a decade of operation. As a result, the study comprehensively studies the long-term performance of anchor bolts in steel–UHPC composite pavement. The study established a finite element model of steel–UHPC pavement based on the mechanical properties of studs obtained from the field push-back tests, and the mechanical properties of studs were modeled by COMBIN39 and COMBIN14 elements. The reasons for the degradation of the bolt performance were analyzed by combining the anchorage force transfer model of the composite beam and the fatigue formula of the stiffness degradation of the bolt, based on the results of the finite element method. The study revealed that the stress of the anchor bolts gradually equilibrates along the longitudinal direction after prolonged service, with the end anchor bolts experiencing an offloading phenomenon and the middle span anchor bolts experiencing an increasing load phenomenon. Furthermore, the study identified the residual slip at the interface of the anchor bolt as a significant factor in the longitudinal stress redistribution of the anchor bolt, and construction errors further promoted stress redistribution. The study’s findings contribute to advancing the design and construction of steel–UHPC composite pavement. Additionally, the study proposes a novel approach to accurately evaluate the stiffness of pavements by combining the anchor bolt extrapolation test with a finite element model, with a maximum error of no more than 5 percent, which can be applied in future pavement design and construction.
15 February 2025 in Tehnicki vjesnik - Technical Gazette
At present, the application scenarios based on BIM+GIS technology are widely used in various infrastructure industries. However, in the process of 2D to 3D transformation, the application scenarios of multi-source heterogeneous data fusion in the rec...