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In recent years, efforts have been devoted to utilizing terrestrial laser scanning for bridge spatial performance inspection, but they are still restricted to small or medium-span bridges, like some historical heritages. Due to the large-scale dimensional features of long-span bridges, applications of 3D point cloud techniques still remain challenging, such as the extra-long scan range and extreme-small incidence angle when scanning a bridge with a span over 1000 m. Moreover, rare attempts can be found for the performance evaluation of point cloud registration methods for long-span bridges as well, which is a critical basis for further spatial deformation recognition on the point cloud data. Hence, in this study, a cross-evaluation of three iterative closest point (ICP) registration methods is conducted for long-span suspension bridges, namely, traditional ICP, kd-tree-based ICP, and feature point-based ICP algorithms. We conducted field laser scanning on the Ma’anshan Yangtze Bridge, an 1880 m long suspension bridge located in China. The results show that the feature point-based ICP algorithm outperforms the other two in terms of convergence rate and execution time for a single iteration due to the smaller number of registration points compared to the other two algorithms. Moreover, it also gives more precise values in terms of bridge tower spatial deformation identification. Meanwhile, due to efficient data organization, the kd-tree-based ICP algorithm takes less time for a single iteration than the traditional ICP algorithm. Finally, two suggestions for algorithm improvement in terms of efficiency optimization and accuracy improvement of long-span bridge deformation analysis are proposed based on the assessment results.

In a strong crosswind, the wake of a bridge tower will lead to an abrupt change of the aerodynamic forces acting on a vehicle passing through it, which may result in problems related to the transportation safety. This study investigates the transient aerodynamic characteristics of a high-speed train moving in a truss girder bridge and passing by a bridge tower in a wind tunnel. The scaled ratio of the train, bridge, and tower are 1:30. Effects of various parameters such as the incoming wind speed, train speed, and yaw angle on the aerodynamic performance of the train were considered. Then the sudden change mechanism of aerodynamic loads on the train when it crosses over the tower was further discussed. The results show that the bridge tower has an apparent shielding effect on the train passing through it, with the influencing width being larger than the width of the tower. The train speed is the main factor affecting the influencing width of aerodynamic coefficients, and the mutation amplitude is mainly related to the yaw angle obtained by changing the incoming wind speed or train speed. The vehicle movement introduces an asymmetry of loading on the train in the process of approaching and leaving the wake of the bridge tower, which should not be neglected.

The aerodynamic characteristics (research on the aerodynamic coefficients and surface pressure coefficients of trains at different wind yaw angles) and dynamic performance (research on the safety and comfort of train operation at different wind speeds and train speeds) of moving trains need to be explored to accurately evaluate their safety in a more realistic scenario. However, tests for a moving train model are costly and difficult to implement. In this paper, numerical simulations are conducted to investigate the aerodynamic characteristics and dynamic performance of moving and stationary trains. The surface pressure distribution and aerodynamic coefficients of the train are analyzed in detail. The results show that the three-component force coefficients of the stationary train are larger than those of the moving train when the wind yaw angle is less than 30∘. At different train speeds and wind speeds, the running safety index based on the aerodynamic characteristics of the stationary train is larger (safer) than that of the moving train. However, the result of the comfort evaluation based on the aerodynamic characteristics of the stationary train may be too conservative. Moreover, the traditional formula is improved to more precisely predict the aerodynamic coefficients of the train within a wide range of wind yaw angles. Compared with the traditional formula, the improved formula only requires the three-component force coefficient of the vehicle at a 45∘ wind yaw angle, and the wind load of the train is independent of its speed. Hence, it is simpler and more convenient to calculate the wind load of the train. This work proves that it is feasible to estimate the aerodynamic force coefficients of moving trains by static wind tunnel tests combined with the improved formula.

In this paper, the dynamic amplification factors (DAFs) of high-speed railway continuous girder bridges are studied. The vehicle-bridge interactions (VBIs) of 13 concrete continuous girder bridges with spans ranging from 48 to 130 m are analyzed, the influences of the train speed, the train marshalling and the bridge fundamental frequency on the DAF are investigated, and the DAF design standard for high-speed railway bridges is discussed. The results indicate that for the continuous beam bridge whose fundamental frequency is less than 3.0 Hz, the maximum DAF is no more than 1.15; while for the bridge examples with a fundamental frequency larger than 3.0 Hz, the maximum DAF reaches 1.25 because the resonance occurs at high train speed. The empirical formulas of the DAFs in the Japan Railway Technical Research Institute (JRTRI) code could provide a conservative estimation of the DAFs of high-speed railway continuous bridges.

This work provides a comprehensive review of the development and applications of bridge rotation construction methods (BRMs) and related critical construction technologies in China. A brief history of BRMs and an outline of their categories, including the rotating structural system, are given first. Subsequently, a discussion on the recent practice of BRMs in China is carried out from three types of bridges: (1) continuous beam and rigid frame bridges; (2) arch bridges; (3) cable-stayed bridges. For each group, a survey of the vital bridge cases that have adopted BRMs in China in the past two decades is provided. Key parameters, including the structure weight of rotation, maximum cantilever span, and rotation duration, are also compared and discussed. Afterward, the principles and applications of the weighing test and the spherical hinge stability, which are both related to the safety of the horizontal rotation construction process, are analyzed in the paper. Additionally, the limitations of BRMs are presented and discussed, and the article concludes with a summary of the current use and future trend of BRMs. The information and experience of BRMs provided in this work can be referenced by engineers and researchers who are devoted to the construction of bridges.

In the event of partial damage to the wind barriers installed on a bridge, the wind loads of a train will change abruptly as they enter and exit the damaged area, resulting in the deterioration of the train running safety. This study aimed to assess the running safety of a CRH2 high-speed train traversing a four-tower cable-stayed bridge with damaged wind barriers. Formulas were deduced for the static and dynamic wind loads on the bridge and train and their combined effect. The aerodynamic coefficients of the train and bridge were obtained through wind tunnel tests of a train–bridge sectional model, and a model of the wind–train–track–bridge coupled system was established using multi-body dynamics and the finite element method. The effects of the length of the damaged area and average wind speed on the train running safety were investigated based on the proposed model. The results reveal that the car body lateral displacements and accelerations reach their maximum amplitudes when the vehicles enter and leave the damaged area, respectively. The amplitude of the car body lateral displacement increases as the length of the damaged area increases, until it reaches 72[Formula: see text]m. The wheel load reduction rates (WLRRs) and derailment coefficients (DCs) of the vehicles increase owing to the damage of the wind barriers; however, the percentage increases for each vehicle are considerably different. The train can safely traverse the damaged area of wind barriers at a designed speed of 180[Formula: see text]km/h when the average wind speed is lower than 10[Formula: see text]m/s. When the average wind speed reaches 20[Formula: see text]m/s, the train can still safely cross the damaged area if the length of the damaged area is less than 12[Formula: see text]m.

With rapid industrial development, the overloading of bridges caused by heavy multi-axle vehicles has become a critical problem worldwide. This work conducts a performance-based evaluation for tied-arch bridges subjected to heavy multi-axle vehicles, and a prediction function of the dynamic impact factor (DIF) for tied-arch bridges is proposed considering the bridge frequency, vehicle speeds, and road quality level. Specifically, the main parameters affecting the bridge response were first identified theoretically using a simplified multi-axle vehicle-bridge model. A tractor-trailer mechanical model and a tied-arch bridge model were subsequently constructed and coupled using displacement coordination conditions to explore the characteristics of the bridge response under heavy multi-axle tractor-trailers. Additionally, based on the identified factors, a detailed investigation of DIF was performed using the developed special vehicle-bridge interaction model. Finally, a suggested computational method for predicting DIF of tied-arch bridges was proposed. The results obtained indicate the impact effect of special tractor-trailers on bridges should not be ignored, even at low operating speeds and in good road conditions. Moreover, additional monitoring measures should be placed on the structural components that are sensitive to dynamic responses to regulate responses within an acceptable range.

Many engineering systems, from subsea pipelines to space structures, from moving vehicles to stationary skyscrapers, are subject to unwanted vibration excitations. Often vibration control can be considered as a problem of energy dissipation and vibration damping. The aims of this issue are to accumulate, disseminate, and promote new knowledge about vibration control, especially for topics related to energy dissipation methods for vibration damping. Topics in this issue reflect the start-of-the-arts in the field of vibration control, such as inerter dampers and pounding tuned mass dampers (PTMDs). This special issue also reports other types of new energy dissipation devices, including a multi-unit particle damper, a nonlinear eddy current damper, and layered dampers. Also reported in this issue are structural elements with innovative designs to dissipate energy. In addition, this special issue also reports two research studies on the dynamic responses of a structural foundation and an earth-retaining structure. Though most papers in this special issue are related to passive methods, one paper reports a semi-active vibration control via magnetorheological dampers (MRDs), and another two papers report active vibration controls using piezoelectric transducers and inertial actuators, respectively.

The traditional curing method of concrete members in China is through manual water curing based on the experience of engineers and at an arbitrary time. This method, however, may induce early-age cracks and reduce durability of materials. In this paper, an automated curing system is proposed, which can decrease and even eliminate the early-age cracks by controlling the relative humidity and temperature of the concrete. More specifically, (1) the interval time of curing spray, calculated based on the cement hydration and real-time monitored data, is automatically identified by a programmable logic controller; and (2) the fog spray curing is operated under a constant water pressure by a variable frequency technology. A field test was conducted on 20 box-section beams to evaluate the performance of the proposed system based on the temperature evolution, humidity variation, and compressive strength of the concrete. Compared with the traditional manual water curing, the concrete beams cured by the automated system show higher early-age compressive strength, better appearance without water stains, and no early-age cracks.

To overcome the drawbacks of bond-type anchors for carbon fiber–reinforced polymer (CFRP) cables, an innovative bonded anchor with steel wedges at the free end is developed in this study. T...

The technique of prestressing near-surface-mounted (NSM) carbon fiber–reinforced polymer (CFRP) has good potential and future prospects for structural strengthening due to its improvement o...

Reasonable assessment of web cracking probability is essential to ensure the service performance of corroded prestressed concrete (PC) bridges. In this paper, a time-dependent prediction model of effective prestress for different prestress tensioning techniques and a corrosion propagation model are established. Meanwhile, an assessment approach of web cracking probability considering both aleatory and epistemic uncertainties is proposed. The case analysis results show that the doubled-tensioned prestress technique is obviously more effective in decreasing the web cracking probability than the traditional prestress tensioning technique. The existing probabilistic method that only considers the aleatory uncertainty may greatly underestimate the probability of web cracking. In comparison, the fastest time to reach the threshold value of web cracking probability when considering the epistemic uncertainty is over 11% earlier than that of using the existing methods. Additionally, the epistemic uncertainty of the chloride diffusion coefficient among the selected corrosion parameters has a most significant impact on the probability of web cracking. Therefore, the epistemic uncertainty of corrosion parameters, especially for the chloride diffusion coefficient, should be minimized as much as possible in this assessment process.

Cancer risk associated with topical calcineurin inhibitors (TCIs) remains unclear.To evaluate the association between TCIs and cancer among patients with atopic and endogenous eczema.Incident cancers were identified from the National Cancer Registry. Data were analyzed using the Cox proportional hazards model to estimate hazard ratios (HRs) and 95% confidence intervals.880 unique cases of cancer developed in 66 176 patients from 2004 to 2012. The adjusted HRs for overall malignancy were 0.82 (95%CI 0.44-1.39) for tacrolimus-exposed and 1.30 (95%CI 0.59-2.45) for pimecrolimus-exposed. The only significant cancer association observed was lymphoid leukemia among the tacrolimus-exposed: HR 7.58 (95%CI 1.64-25.8). All affected patients had young-onset B-cell leukemia. Subgroup analysis of pediatric patients (≤16 years) showed significant association between tacrolimus use and B-cell leukemia: HR 26.4 (95%CI 4.77-146).In this first Asian study on the risk of TCIs and malignancies, we do not find an association between use of tacrolimus and pimecrolimus in atopic and endogenous eczema and the overall development of malignancies. However, the use of topical tacrolimus was found to be associated with the development of B-cell acute lymphoid leukemia in pediatric eczema patients; further studies are required to investigate if a true association indeed occurs.

The influence of 0.42 and 0.72 wt.% Zn on the intergranular corrosion (IGC) of Al–3.7Cu–1.15Li–0.5Mg and Al–2.7Cu–1.7Li–0.3Mg alloys (representing different Cu/Li ratios) was investigated. IGC dependence on ageing time was studied and a primitive IGC diagram established. With ageing, the potential of the Al –x Cu –y Li alloys lowered due to precipitation, accompanied by grain boundary precipitate coarsening. Concomitantly, corrosion mode evolved with ageing from pitting and local IGC (early ageing), general IGC (under-aged), local IGC (near peak-aged) and pitting (over-aged). Of key interest is that Zn additions remarkably decreased the IGC sensitivity of the Al–2.7Cu–1.7Li–0.3Mg.

Summary This paper discusses the application of a connected pipe system (CPS) to a suspension bridge in China for the purpose of vertical deflection monitoring and assessment. The CPS mainly consists of three main parts: the pressure transmitters to detect the height change of liquid, the pipes to connect the reference point and measurement points, and the liquid to fill the connected pipes. Multiple pressure transmitters, taken as the measurement point, were mounted inside of the girder. A reference transmitter was mounted inside of a tower, taken as a fixed point. To verify the performance and reliability of the CPS, a controlled load test after the completion of the bridge construction and an uncontrolled load test under the actual traffic loading were carried out. The results showed that the CPS exhibited excellent capability in real-time measurement of vertical deflection of the suspension bridge. With the long-term deflection data monitored by the CPS, the extreme deflections with respect to vehicle loads were predicted by extreme value analysis. The generalized extreme value distribution was adopted to establish the probability models of the daily maximum and minimum deflection sequences, and then the extreme deflections within the design reference period of 100 years were determined based on the probability models. Comparison of the extreme deflections and the deflection thresholds was carried out. The deflection monitoring and assessment method proposed in this paper have shown high potential of applicability in the practice of health monitoring for long-span bridges. Copyright © 2015 John Wiley & Sons, Ltd.

The topic of vibration control and energy dissipation is among the oldest and most relevant in the field of engineering [...]

This article examines the piezoelectric-based energy harvesting on civil infrastructures. Piezoelectric cantilever–based harvesters are adopted considering their wide usage. Four concrete slab-on-girder bridges that represent the majority of bridges in the United States are used as the platforms for the energy harvesting. In the simulation, the distributed-parameter model is used for the energy harvester, while four three-dimensional bridges with HS20-44 truck models are developed using ANSYS and MATLAB. Two scenarios for the bridge–vehicle systems are simulated: bridges with only one passing vehicle and bridges with a continuous vehicle flow. A parametric study is carried out to study the effect of various properties of the bridge and vehicle on energy harvesting. The simulation result shows that the energy output power increases with poorer road conditions and smaller bridge span lengths. Optimal vehicle speeds and energy harvester positions are also investigated and discussed in this article.

In the present study, an experimental setup was made to measure the aerodynamic characteristics of vehicles on the bridge for different cases in a wind tunnel considering the aerodynamic interference. The influence of the wind turbulence, the vehicle interference, and the distance of vehicle from the windward edge of the deck on the aerodynamic coefficients of vehicles were investigated based on the experimental results. The measured results showed that the wind turbulence, the vehicle interference, and the vehicle distance from the windward edge significantly affected the aerodynamic coefficients of vehicles.

The precast ballastless track slab has been widely applied in the Chinese high-speed railway system. However, the current slabs, made of normal concrete (NC) materials and designed in a “plane” structural configuration, were found vulnerable to the train loads and temperature effects. This paper proposed an innovative slab type, which was made of an alternative reactive powder concrete (RPC) material and designed in a “frame” structural type. Four frame slabs with different cross section profiles were parametrically investigated, and the best configuration was proposed. The results demonstrated the proposed RPC slabs can well meet the requirements of the stiffness and strength. Compared with the NC plane slabs, the warping deformation of the RPC frame slabs were decreased as much as by 41.7% and 37.0%, respectively, under the −10°C temperature gradients and the combination of train and temperature effects. The simulated tensile stresses were within the corresponding RPC strength capacity. The crac...

According to electromagnetic bandgap (EBG) structure of the simultaneous switching noise (SSN) suppression mechanism and coplanar EBG structure equivalent circuit model, a novel structure of Meander-L Bridge is proposed for SSN suppression in high-speed circuits. Simulation and measurement results show that the stopband ranging from 210MHz to 20GHz at −30 dB suppression of the bandgap depth. Furthermore, the suppression bandwidth is more than 19.79GHz to achieve the ultra-wideband SSN suppression. Moreover, time-domain simulation results show that the structure in high-speed circuits is met with signal integrity.

The current highway bridge design in the United States follows the AASHTO-LRFD specifications, which prescribe a dynamic load allowance, IM, of 0.33 for the dynamic effect of truck/tandem loading. Studies have shown that the IM value prescribed by the LRFD code may underestimate this dynamic effect under poor road surface conditions (RSCs). One reason for this underestimation is that the IM value employed in the AASHTO specifications was obtained from the statistical properties of the IM relative to average RSC, as defined by the ISO 1995 standards. In addition, the IM, which is a random variable with certain statistical properties, was modeled as a deterministic constant in the code calibration process. In this paper, the reliability indexes of a selected group of prestressed concrete girder bridges, designed following the AASHTO-LRFD code, are calculated by modeling the IM explicitly as a random variable for different RSCs. It is found that although the calculated bridge reliability indexes are usually above the target reliability index value of 3.5 under above-average RSCs, they can be significantly below the target value of 3.5 when the RSCs are below average. Following the load rating procedure proposed by the AASHTO load and resistance factor rating (LRFR) manual, it is also found that the code-employed IM value may overestimate the rating factors when RSCs are below average. Based on these results, appropriate IM values are suggested for different RSCs to achieve a consistent target reliability index and a reliable load rating. The results presented in this paper are particularly valuable for the rating of existing prestressed concrete girder bridges, for which the actual RSCs can be directly evaluated. The RSCs must be properly taken into account to accurately estimate the actual safety of the considered bridge.

This paper describes the initial efforts to explore a new application of metakaolin-based geopolymers to structural health monitoring. A distributed geopolymer-fiber optic sensing G-FOS system is proposed, where geopolymers are used as smart adhesives to affix optical fibers to existing in-service structures to form an integrated G-FOS sensor. Results of feasibility testing in the laboratory indicated that the tensile cracking strain of geopolymers can be controlled by finely tuning the Si/Al ratios or adding appropriate aggregate fillers such as sand, thus rendering the "smart" nature of geopolymers for deformation-based sensing. Geopolymers with SiO2 /Al2O3 ratios 3.8 are viable adhesives that can develop strong bond to concrete, steel, and glass fiber. Laboratory prototype testing on steel specimens under uniaxial tension and on concrete beams under four-point bending validated the concept and feasibility of the proposed G-FOS system for structural health monitoring. It further demonstrated that the G-FOS system cannot only detect overstraining events in steel but also measure the crack size in concrete.