Quansheng Sun’s research while affiliated with Northeast Forestry University and other places

Bridge grid support stability against typhoons is a key factor in ensuring the safety of bridge construction. This study employs wind tunnel force tests and Particle Image Velocimetry (PIV) experiments to investigate the typhoon stability of grid-type high supports. Based on wind tunnel force tests, the static force coefficients of grid-type high supports are measured under different flow conditions and wind angles. Utilizing PIV technology, a novel analysis is conducted on the flow field visualization of high-pier steel tube support models in horizontal and vertical plane flows. Quantitative analyses of the vortex core intensity and turbulence of single and double-pier supports are performed. The impact of wind direction on the aerodynamic characteristics of grid-type high supports is determined.The research indicates significant changes in drag, lift, and torque when calculating the wind resistance of grid-type high supports. Therefore, the influence of static wind loads in three directions needs to be fully considered in the calculations. Under a 45° wind deflection angle, vortex movement becomes more intense, reaching maximum vortex strength and turbulence intensity. This results in an increase in the average and fluctuating aerodynamic forces of the model. Compared to the four-legged grid-type high support model, the six-legged model exhibits relatively smaller vortex strength and turbulence intensity at the vortex core. Noticeable interference exists among the components of the grid-type high support, thus spatial three-dimensional characteristics should be considered in numerical simulations.By conducting wind tunnel experiments on grid-type high supports in typhoon-prone areas, the study ensures the safe use of these supports, enhances economic benefits, and broadens the application scope of grid-type high supports.

In order to reduce the damage of reinforced concrete bridge piers (RCBPs) under vehicle impact scenarios, the Ultra-high performance concrete-Bio-inspired honeycomb column thin-walled structure (UHPC-BHTS) with an attached anti-impact composite structure is designed to enable the pier to resist accidental vehicle impacts during its service life. According to the dynamic response, energy absorption characteristics, and other indicators, the impact protection effectiveness of the UHPC-BHTS composite structure on six RC column specimens with different equivalent heights from 1 to 3.5 m was evaluated. The average proportion of internal energy absorbed by the UHPC-BHTS composite structure was as high as 97.19 %. Then, 48 Ford 800 medium-sized trucks with engine tonnage of 0.64-2 tons and impact speeds of 40-140 km/h were systematically simulated for the vehicle-pier impact condition. Through the test results, it is concluded that the pier protected by the UHPC-BHTS composite structure has a lower damage level than the RCBP without a protective device and can withstand the impact of medium-sized trucks with faster and heavier engines. Finally, based on a new type of damage assessment index, the damage degree of vehicle impact on RCBP was evaluated. The work in this paper can provide a useful reference for the design of RCBP in vehicle impact protection.

In order to prevent the reinforced concrete (RC) structures from being damaged under the overload impact, a new type of composite structure-ultra-high performance concrete (UHPC)-Bio-inspired honeycomb column thin-walled structure (BHTS) was designed in this paper. A scale model with a scaling factor of 1:10 was made. The experimental tests and numerical simulations of RC column and UHPC composite structure were carried out. By comparing the impact force, displacement, shear force, bending moment and energy absorption, the protective effect of the UHPC-BHTS composite structure on RC columns under lateral impact load was evaluated. Then, the failure process of RC column was analyzed, the UHPC-BHTS composite structure absorbed 76.42 % of the impact kinetic energy under the higher energy input condition, the shear failure with large damage to the RC column can be converted into bending failure with small damage. At the same time, a new damage assessment method was used to evaluate the RC column. The results show that the RC column with UHPC-BHTS composite structure can effectively protect the RC column's structural integrity under impact. The design and modeling methods in this research can provide a useful reference for anti-collision design in practical engineering.

This paper investigates the effects on the physical and mechanical properties and microstructure of lime-hemp concrete (LHC) materials at different binder mass ratios. A mixture of three cementitious materials, slaked lime, cement, and coal gangue powder, was used as binder, and hemp shives were used as concrete aggregate, and five test groups were designed, i.e., binder/hemp shives (B/H) mass ratios of 1.2, 1.4, 1.6, 1.8, and 2.0. The physical properties of LHC, including density, drying rate, water absorption, thermal conductivity coefficients, and mechanical properties (compressive strength and flexural strength) with different binder ratios were investigated. In addition, the microstructural properties of 56d LHC were investigated by SEM, XRD, and TG-DTG micro-scale analysis methods. The results showed that with the increase in binder content, the drying speed of LHC became faster, the thermal conductivity coefficients, compressive strength, and flexural strength increased, and the water absorption was just the opposite. With a fit ratio of 2.0, the strength is the greatest and the toughness is the best; with a fit ratio of 1.2, the thermal conductivity coefficient is the smallest and the insulation effect is the best. In addition, the hydration of the binder produced different forms of hydration products (CaCO3 and C-S-H), and the hydration products increased in quantity with the increase of the binder, resulting in stronger CaCO3 and C-S-H diffraction peaks. The hydration products produce a better bond with the rough cannabis particle surface, filling the internal voids of the LHC, improving the density of the material, and enhancing the mechanical properties of the material.

Due to the "bending and torsion coupling" effect of curved bridges, the shear fracture and bending collapse of curved girder bridge piers and columns under the action of earthquakes are more likely to occur, resulting in the serious consequences of the overall collapse or overturning of the bridge structure. Polyurethane cement is a kind of reinforcement material used for structural seismic reinforcement in this case, which has excellent reinforcement performance. In this paper, based on the three-way shaking table test of curved girder bridge, OpenSees finite element software is used to establish the fiber unit model of the abutment specimen, and the model is used to carry out the parameter sensitivity analysis to investigate the influence of the height of abutment and polyurethane reinforcement on the seismic performance of polyurethane cement-reinforced abutment specimen, and it is known that, the higher the abutment is, the worse is the reinforcing effect of polyurethane cement; the higher is the thickness of polyurethane cement, the better is the reinforcing performance of polyurethane cement. The higher the abutment is, the worse the reinforcing effect of polyurethane cement is; the higher the thickness of polyurethane cement reinforcement is, the more obvious the effect of polyurethane cement reinforcement is. Based on the data of parameter sensitivity analysis, the parameters are optimized, and the most economical parameters are derived, thus providing sufficient theoretical basis for polyurethane cement reinforcement of curved beam bridge piers.

To address the issue of excessive mid-span deflection in rigid frame-continuous girder bridges during the later stages of normal use and to provide a basis for setting the pre-camber of this bridge type. This study focused on a specific rigid frame-continuous girder bridge. Based on the outcomes of finite element analysis, a GM(1,1) model developed using grey theory was utilized to forecast the vertical deflection of the primary girder in the construction phase of a rigid frame-continuous girder bridge, resulting in notable outcomes. The results suggest that the GM(1,1) model grounded in grey theory offers precise estimations of the vertical deflection of the primary girder during the prestressing tendon tensioning stage, displaying a minimal deviation of merely 1.73 mm compared to actual measurements. Consequently, applying the GM(1,1) model based on grey theory for projecting the vertical deflection of the primary girder in the construction process of rigid frame-continuous girder bridges can advance the accuracy of construction management. Through comparative analysis of measured values estimated values and theoretical values at the construction site, it is evident that the predictive model effectively controls the displacement, thus serving as a reference for construction control in similar projects.

Purpose The application of reinforcing old bridges by adding external prestressed steel bundles is becoming more and more widespread. However, the long-term safety performance test of the strengthening method is rarely carried out. In this paper, the bearing capacity of a 420 m prestressed concrete (PC) continuous girder bridge after five years of strengthening is analyzed. Design/methodology/approach The bridge model of the bridge structure and strengthening scheme is established by the finite element software of the bridge. The theoretical load-bearing capacity of the bridge under the latest standard load grade is obtained by finite element analysis. The actual bearing capacity of the bridge is obtained by field test. Through the comparative analysis of theory and practice, the health state of the bridge after five years of reinforced operation is judged. The damage to the overall stiffness and external prestressing of the bridge is also analyzed. Findings The results of deflection and strain show that the stiffness and strength of the secondary side span and the middle span decrease slightly, and the maximum reduction of bearing capacity is 4.5%. The static stiffness of the whole bridge decreases as a result of cracks, and the maximum decrease is 21%. In the past five years, the relaxation loss of the external prestressing of the bridge is 3.31–3.97%, which is the main reason for the decrease in bearing capacity. Originality/value Through the joint analysis of the bridge stiffness and the loss of external prestressing, the strengthening condition of the bridge after five years of operation is effectively analyzed. The strengthening effect of the external prestressed steel beam strengthening method is analyzed, which can provide a reference for similar bridge strengthening.