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This paper presents an experimental and numerical investigation into the bending behaviour of reinforced concrete (RC) T-beams damaged by overheight vehicle impact strengthened with ultra-high performance concrete (UHPC). Four-point bending tests were conducted on one RC T-beam and six UHPC-strengthened RC T-beams, and the primary parameters included the length and thickness of the UHPC strengthening layer, as well as the filling area of UHPC for the damaged region. The test results demonstrated that the UHPC strengthening layer effectively delayed the development of concrete cracks, improved the bending stiffness, cracking load, and resistance of the T-beams. The UHPC-strengthened T-beams exhibited an increase in cracking and ultimate loads by 39–339 % and 26–113 %, respectively, compared to the RC T-beam. Subsequently, a finite element (FE) model of the UHPC-strengthened T-beams was developed and validated using the experimental results. A parametric study using the validated FE model was conducted, revealing that insufficient strengthened length or excessive strengthened thickness of the UHPC layer increased the risk of debonding failure. Furthermore, for T-beams experiencing bending failure, increasing the thickness and height of the UHPC layer, as well as the UHPC filling area for the damaged region, significantly improved the bending resistance, while the UHPC layer length had little effect on the bending resistance. Finally, based on the calculation theory of RC beams under bending loads and considering the strain-hardening behaviour of UHPC in tension, a design method for the bending resistance of damaged RC T-beams strengthened with UHPC was proposed and verified using the experimental and numerical results.

Dynamic factor (DF) is an important indicator for describing the dynamic action of a train on a bridge. For small- and medium-span bridges, although existing research and codes have studied and specified the DF of steel–concrete composite beam bridges, few studies have been refined to steel-plate–concrete composite beam bridges (SPCCBs), and the effect of eccentric loads has not been considered. Considering the poor torsional properties of SPCCBs, a double-line railway SPCCB was used as the background, and the DF under eccentric loads was investigated. The results show that the DF increased with an increase in the bridge fundamental frequency. Resonance is produced when the train travel speed and bridge frequency meet a certain relationship, which in turn significantly increases the DF. The DF generated by a single-car train is larger than that generated by a multicar train in the conditions of nonresonance speed interval. Finally, an empirical formula that is more applicable for describing the DFs is proposed based on the results of numerous numerical analyses. In the design of railway SPCCBs with small- and medium-spans, the DFs used in national codes that do not consider the eccentric load are considered unsafe and can be appropriately adjusted upward. The study can provide support for the rapid design of double-line railway SPCCBs with small- and medium-spans.

In this study, the reinforced concrete (RC) beams were strengthened by use of carbon fiber reinforced polymer (CFRP) and engineering cementitious composite (ECC). The flexural behavior of the strengthened RC beams was investigated experimentally, and analytical prediction methods were used to verify the experimental results. The experimental results showed that, the premature delamination between CFRP plate and concrete occurred if the beam was solely reinforced by CFRP, nevertheless, this can be effectively prevented by the composite use of CFRP and ECC. Compared with reference beam, the CFRP-ECC composite strengthened technique significantly enhanced the cracking load, yield load, and ultimate load of beams up to 23–31 %, 4–6 %, and 5–10 %, respectively, in addition, the stiffness, ductility, and energy absorption capacity (EAC) can also be enhanced upon the composite strengthening. In final, the prediction model has high accuracy, and the error variation within 5 % when comparing the predicted and tested values of flexural bearing capacity.

The flexural behaviour is investigated in this paper for engineered cementitious composite (ECC)-reinforced concrete (RC) composite beams. The thickness and shape of the ECC layer are the variables studied. ECC has proved to be one of the ideal construction materials for improving the flexural capacity of reinforced conventional concrete beams. When the composite beam specimens reached the load-bearing limit state, only dense micro-cracks appeared in the ECC layer in the tensile zone, and no local fracture was observed in the test, reflecting the high ductility of ECC. The load values for all phases of the ECC-RC composite beams are higher than those of the RC beams, suggesting that the composite beams have better ductility and energy absorption capacity. In addition, the ability of the U-shaped ECC layer composite beam to limit crack development and the synergistic effect with the reinforcement is superior compared to the other tested beams. Finally, considering the strain-hardening characteristics of ECC, based on the force equilibrium conditions, the formulae are derived for the flexural capacity of ECC-RC composite beams.

For noncompact composite girders widely employed in bridge structures, the design can be more reasonable and economical if the shear contribution of concrete slabs is considered. In this study, the ultimate shear resistance of composite girders with noncompact sections under positive moments was investigated using the finite element method (FEM). The validity of the FEM was verified using existing test data. Subsequently, parametric studies were performed using the validated FEM. It was shown that the concrete slab thickness and web height-to-thickness ratio had notable effects on the shear resistance of the slab; the concrete slab width had a negligible effect on the shear resistance if its value exceeded twice the web height; the web aspect ratio mainly affected the shear resistance of the web. The numerical results indicated that the shear resistance of the composite girder was 1.02–1.63 times of that calculated using the ASSHTO code, and 1.12–1.55 times of that calculated using the EC4 code. After comprehensively considering the effects of these parameters, a design equation for predicting the shear resistance of noncompact composite girders under positive moments was suggested and verified using numerical and test data.

Abstract Background Largely due to incidental detection, asymptomatic pancreatic cystic lesions (PCLs) have become prevalent in recent years. Among them, intraductal papillary mucinous neoplasm (IPMN) infrequently advances to pancreatic ductal adenocarcinoma (PDAC). Conservative surveillance versus surgical intervention is a difficult clinical decision for both caregivers and PCL patients. Because RNF43 loss‐of‐function mutations and KRAS gain‐of‐function mutations concur in a subset of IPMN and PDAC, their biological significance and therapeutic potential should be elucidated. Methods Pancreatic Rnf43 knockout and Kras activated mice (Rnf43−/−; KrasG12D) were generated to evaluate their clinical significance in pancreatic pre‐neoplastic initiation and malignant transformation. Results Loss of Rnf43 potentiated the occurrence and severity of IPMN and PDAC in oncogenic Kras mice. The Wnt/β‐catenin signaling pathway was activated in pancreatic KrasG12D and Rnf43 knockout mice and the PORCN inhibitor LGK974 blocked pancreatic IPMN initiation and progression to PDAC accordingly. Conclusions Rnf43 is a tumor suppressor in the prevention of pancreatic malignant transformation. This genetically reconstituted autochthonous pancreatic Rnf43−/−; KrasG12D preclinical cancer model recapitulates the pathological process from pancreatic cyst to cancer in humans and can be treated with inhibitors of Wnt/β‐catenin signaling. Since the presence of RNF43 and KRAS mutations in IPMNs predicts future development of advanced neoplasia from PCLs, patients with these genetic anomalies warrant surveillance, surgery, and/or targeted therapeutics such as Wnt/β‐catenin inhibitors.

The shear behavior of shear connectors in steel-concrete composite structures mainly depends on its load-slip relationship. The load-slip relationship not only reflects the shear capacity and slip capacity of the shear connectors, but also the degradation of shear stiffness during loading. In this study, fifteen push-out tests were carried out to investigate the load-slip relationship of the novel bearing-shear (B-S) connectors, which consist of pressuring-bearing plates and shear plates. Based on push-out tests, the influence of the shape and height of the pressure-bearing plate, and the shear plate shape on the load-slip relationship of the B-S connectors was analyzed. Then, an effective finite element model, validated by push-out tests, was used to study the influence of the concrete strength, and the thickness and tensile strength of the shear plate on the load-slip relationship of B-S connectors. Finally, based on the push-out tests, numerical analysis and theoretical analysis, an analytical model expressing the load-slip relationship of the B-S connectors was proposed.

Vehicle load is an important factor for the fatigue damage of the orthotropic steel decks. The traffic vehicles for port highway in China are mainly multi-axle container trucks, which show different characteristics from conventional highways. Based on the multi-period traffic flow data collected by weight-in-motion system of a bridge over the sea in Zhejiang, China, this study has investigated the traffic load characteristics of the port highway bridge. Eight typical vehicles of fatigue load spectrum are classified according to the number of axles and wheelbase. The distribution characteristics of the gross vehicle weight (GVW) and axle weights of typical vehicles are analyzed by lane. Depended on the equivalent fatigue damage principle, the vehicle load spectrum for fatigue evaluation of the port highway bridges is established. The results show that the average proportion of the trucks (weighing greater than 3 tons) in the total traffic flow is 73.2%, and trucks with more than four-axle accounted for 89.0%. Heavy vehicles are mainly concentrated on the outer lanes, and the probability of vehicles driving in the heavy lane increases with the increase of gross vehicle weight. The maximum equivalent gross vehicle weight is 62.5 tons, which appeared in V7 in the exiting island direction. The simplified fatigue vehicle model in the heavy lane for Chinese port highway bridges is proposed, based on the six-axle vehicle which contributed the most fatigue damage. The proposed fatigue load model can better represent the actual traffic load level of port highway bridges in China.

The complex and diverse structural forms make it impossible to define universal shape coefficients for large-span roof structures, which usually need to be obtained by wind tunnel tests. However, the number of test measurement points is limited, which leads to obvious limitations in the study of wind loads on large-span roof structures. Taking a large-span folded-plate roof as an example, based on the wind tunnel pressure test results of the rigid model, the proper orthogonal decomposition (POD) method is used to reconstruct the wind pressure field of the roof using the first several eigenmodes. The wind pressure of several typical characteristic points is predicted based on four different interpolations methods, and the accuracy and feasibility of POD method in reconstruction and prediction of wind pressure field of large-span roof are analyzed and studied from multiple perspectives. The results show that the order of the selected structural eigenmodes has an impact on the reconstruction accuracy of the wind pressure field. The more orders are selected, the closer the wind pressure field reconstruction is to the true value. The reconstruction effect of the wind pressure field based on the POD method is related to the spatial position of the predicted point, and the reconstruction effect of the wind field based on the fluctuating wind pressure is obviously better than the that based on the mean wind pressure. When the POD method is used to predict the wind pressure of an unknown point, different interpolation methods can achieve ideal results. Among them, the bilinear interpolation method has the highest prediction accuracy, and the adjacent point interpolation method and Griddata V4 interpolation method only have certain errors in the low frequency region.

Steel bottom plates are applied as replacements for the concrete bottom plates in order to reduce the dead weight of the composite box girders with corrugated steel webs and steel bottom plates (CSWSB). Due to the change in the material, the previous analytical calculation methods of vertical deflection of composite box girders with corrugated steel webs (CSWs) cannot be directly applied to the improved composite box girders. The shear lag warpage displacement function was derived based on the shear deformation laws of the upper flange and the bottom plates of the improved composite box girders. The equations for the calculation of the shear deformation and the additional deflection due to the shear lag of continuous and simply supported composite box girders with CSWSB under concentrated and uniformly distribution loads were derived by considering the double effects of the shear lag and the shear deformations of the top and the bottom plates with different elastic moduli. The analytical solutions of the vertical deflection of the improved composite box girders include the theory of the bending deflection of elementary beams, shear deformation of CSWs, and the additional deflection caused by the shear lag. Based on the theoretical derivation, an analytical solution method was established and the obtained vertical deflection analytical solutions were compared with the finite element method (FEM) calculation results and the experimental values. The analytical equations of vertical deflection under the two supporting conditions and the two load cases have verified the analyses and the comparisons. Further, the additional deflections due to the shear lag and the shear deformation are found to be less than 2% and 34% of the total deflection values, respectively. Moreover, under uniform distributed load conditions, the deflection value was found to be higher than that of the under concentrated load condition. It was also found that the ratio of the deflection caused by the shear lag or the shear deformation to the total deflection decreased gradually with the increase in the span width ratio. When the value of the span width ratio of a single box and single chamber composite box girder with CSWSB was equal to or greater than 8, the deflections caused by the shear lag and the shear deformation could be ignored.

The traditional method for calculating the buffeting response of long-span bridges follows the strip assumption, and is carried out by identifying aerodynamic parameters through sectional model force or pressure measurement wind tunnel tests. However, there has been no report on predicting the buffeting response based on the sectional model vibration test. In recent years, the author has proposed a method, based on the integrated transfer function, for predicting the buffeting response of long-span bridges through theoretical and full-bridge tests. This provided an idea for predicting the buffeting response based on the sectional model vibration test. Unfortunately, the effectiveness and accuracy of this method have not been proven or demonstrated through effective tests. To solve this problem, a long-span suspension bridge was taken as a background. Parameters such as aerodynamic admittance were identified through a sectional model force measurement test and the integrated transfer functions were identified through a sectional model vibration test. A taut strip model test was also conducted. Furthermore, the buffeting response prediction results based on three kinds of wind tunnel test techniques were compared. The results showed that if the strip assumption was established, the results of the three methods aligned well, and that selecting a reasonable model aspect ratio for the test could effectively reduce the influence of the 3D effect; moreover, identifying the integrated transfer function by the sectional model vibration test could effectively predict the long-span bridge buffeting response. Furthermore, when the strip assumption failed, the results of the traditional calculation method using 3D aerodynamic admittance became smaller. A larger result would be obtained by neglecting the influence of aerodynamic admittance.

Evaluating corrosion of steel bars within concrete cross section was the major task for durability of reinforced concrete structures. Although plenty of steel bars with various boundary condition caused huge computation load in numerical simulation, most of them were in different geometric locations while their other configuration was similar, such as temperature, moisture, and concrete composition. In this article, shape-based estimation approach was introduced for simplifying assessment of durability of concrete structures regarding numerical simulation. Based on the same penetration condition and diffusing media, the similarity of geometric configuration was the primary consideration of shape-based estimation and a mathematic model regarding the length of involving outline within a circular region with given radius was proposed. The crossbeam of an aged reinforced concrete arch bridge in coastal area was assessed, based on which shape-based estimation was proved to be applicable by comparing with finite element analysis. An evaluating tools called Weighed Corrosion Index in terms of corrosion degree of rebar in the whole concrete section was proposed and discussed in the application on degradation of concrete members. Moreover, for the purpose of modeling and post-processing, designed rebar within concrete section might not be exactly occupied by the nodes of meshed section and thus, content of aggressive agent cannot be directly obtained. An approach for identifying of rebar position and interpolating the content at rebar position was introduced.

To improve the ignition and combustion performance of aviation kerosene, two-channel gliding arcs plasma was adopted to crack kerosene into active components, such as gaseous light hydrocarbons and H2. The influence of carrier gas flow rate on discharge characteristics and cracking effects were investigated. Experimental results indicate that, compared to single channel discharge, the power of two-channel gliding arcs discharge is greater while the arcs cover twice as much area as that of single channel discharge. The cracking rate of two-channel discharge plasma is greater than that of single channel discharge while it shows an upward trend with greater carrier gas flow rate. Among the main components of cracking gas, the molar percentage of hydrogen is the highest and exceeds 50%. Greater carrier gas flow rate would result in lower molar percentage of hydrogen. Interestingly, the ethyl group prefers to form C2H2 as the carrier gas flow rate increases in the two-channel gliding arcs discharge while the molar percentage of C2H2 and C2H4 changes inconspicuously in the single channel discharge.

In this study, the thermal characterisation of dielectric barrier discharge plasma actuation driven by radio frequency (RF) voltage waveform at low pressure is studied. The RF discharge images and voltage–current waveforms are quite different under 3 and 40 kPa. The thermographic method has been proposed for the spatial–temporal temperature field on the actuator surface

A double-column self-centering pier fused with shear links is a novel structure developed to reduce residual deformation and facilitate post-earthquake repair. With this novel structure, the seismic resilience of bridges can be improved, and the reliability of lifeline infrastructure can be ensured. This paper presents the proposed pier configuration and investigates the mechanical behavior of the pier. A simplified finite element model is established to develop the lateral force-displacement relationship under cyclic loading. Additionally, a theoretical model based on the matrix displacement method and the virtual work principle is proposed to calculate the lateral force-displacement skeleton curve. The rationality and reliability of the theoretical model are validated by the satisfactory agreement observed between the numerical and theoretical results. Furthermore, a series of parametric analyses are conducted to discuss the effects of key parameters. The outcomes of this work can serve as a reference for further development of the design method for the innovated pier.