Wen Xiong

Concrete has been widely adopted as the primary material for bridge foundations. Although it has good performance against corrosion, abrasion damage has become a common threat to bridges exposed to sediment-laden flow. The smoothed particle hydrodynamics (SPH) approach can explicitly account for collisions among sediment particles and provides a useful tool for predicting abrasion damage. To support practical bridge design, it is essential to investigate how abrasion damage evolves under varying hydraulic and structural conditions. This paper presents a durability analysis of bridge foundations subjected to sediment-induced abrasion. First, an SPH-based abrasion solver was developed by embedding a composite abrasion model that accounts for momentum transfer during particle rebound. The accuracy of the solver in predicting abrasion damage was validated. Then, the relationship between hydraulic and structural parameters and the resulting abrasion rate was established through a series of parametric studies. A prediction formula for abrasion rate was derived using the response surface method. The time-varying abrasion depth of a bridge pier was predicted using a series of stochastic flow discharge data. Finally, the long-term durability of the bridge was assessed by comparing percentile distributions of abrasion depth over different service periods with the design thickness of the protective concrete layer. The estimated service life ranges from 8.95 years at the 5th percentile to 9.37 years at the 95th percentile when the design concrete cover thickness is set to 60 mm. The findings provide a practical approach for predicting the service durability of bridges subjected to abrasion.

Concrete has been used primarily in bridge foundations due to its low cost, easy availability, and other advantages. However, many bridges experience substantial abrasion within a fraction of their designed service life despite having thicker protective layers according to design code specifications. Most of the abrasion models in commercial software are empirical, derived from experiments with metal materials, and might not satisfy the prediction of concrete abrasion. CFD models in abrasion analysis neglect collisions between sediment particles and the restitution coefficient for particle–structure wall collisions. To bridge the gap, this study developed an abrasion solver to investigate the durability of concrete bridge foundations under abrasion. It improved existing composite abrasion models with momentum theory, considering sediment rebound after impact to enhance abrasion predictions. The model was embedded in a secondarily developed smoothed particle hydrodynamics (SPH) solver. The accuracy of the SPH abrasion solver and the proposed abrasion model was validated according to the results of representative concrete plate abrasion experiments. Finally, the durability of a bridge pier was quantified using the thickness of the concrete protection layer as a basis. The findings offer a practical approach for predicting the abrasion resistance of bridges in environments with high exposure to waterborne sediment, ultimately improving the design and maintenance of bridge foundations in such conditions.

Tendon eccentricity produces non-uniform grout thickness within ducts in bonded post-tensioned concrete structures. Its implications for bond behaviour were investigated through 53 pull-out tests on mono- and triple-strand tendons embedded in grouted corrugated steel ducts within concrete cylinders. Eccentricity was varied at ambient temperature, whereas tests during heating and after cooling used the maximum eccentricity for each tendon configuration. The programme covered 20–600 °C and included comparisons of water cooling for mono-strand specimens and helical confinement for triple-strand specimens. Increasing eccentricity reduced ambient-temperature bond strength. Bond strength and initial stiffness decreased with temperature, with the fitted relationships indicating reductions to half their ambient-temperature values at approximately 242 °C and 118 °C, respectively. Bond strength recovered slightly after cooling, and water- and air-cooled mono-strand specimens showed similar responses under the tested conditions. For specimens classified as having medium confinement, post-peak residual bond strength averaged approximately 70% of the corresponding characteristic bond strength, while specimens exhibiting through splitting retained little residual resistance. Helical reinforcement improved the post-peak response of triple-strand tendons, although its contribution to bond strength was limited at 100–300 °C when concrete cover spalling occurred. The results were used to recalibrate a trilinear bond–slip model for the observed confinement conditions.

Because of undesired hydraulic effects, bridge collapse accidents have become increasingly frequent during the flooding season considering that hydraulic effects on bridge design are paramount to controlling and mitigating hydrological damage. Previous studies have made important progress in assessing bridge performance under flood-induced scour, including time-dependent scour reliability, probabilistic scour vulnerability, and the life-cycle performance of bridges under multiple hazards. However, limited attention has been paid to the design-oriented lifetime reliability assessment of bridges subjected to accumulated foundation scour resulting from successive flood events. To bridge this gap, this study conducted a lifetime reliability analysis against floods, incorporating structural, hydraulic, and geological characteristics. First, a probabilistic scour prediction throughout service life was performed to determine the time-varying scour depth. Then, a refined finite-element model of a bridge was constructed considering soil–pile interaction and scour morphology. Next, the capacity of the pile foundation under floods and service loads was calculated to determine the reliability of bridges under given scour depths. Finally, a lifetime reliability evaluation with and without considering scour accumulation under repeated flood events was conducted. The reliability of the bridge, considering scour accumulation and climate change, decreased to 0.89 after 200 years of service, while that without considering scour accumulation and climate change decreased to 0.01. This paper reveals the necessity of considering scour accumulation throughout service life in bridge design. The proposed lifetime reliability assessment framework can effectively and economically enhance bridge safety against floods.

The design of bearing capacity is essential for enhancing the resistance of bridge foundations to scour-related damage. However, most studies estimate this capacity solely based on visible ...