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Due to the strike of wind-blown raindrops, the pressure caused by wind and rain on building facades is different from the action of wind-only. The wind–rain induced pressure during Typhoon Haikui (2012) was collected at three taps on the windward side of Tongji University experimental building which was located near the coast of East China Sea. The observed data during the storm was compared with both the data of normal wind events without rains and wind tunnel test. The results show that the presence of driving rains intensifies the wind effects acting on the windward side of the building. More specifically, the mean wind–rain induced pressure coefficients at the three locations of the experimental building are larger than those collected from the strong wind-only events and the wind tunnel test when the wind direction ranges from 110° to 130°. It was also found that the mean wind–rain induced pressure coefficients at each tap increase in magnitude with rainfall intensity and the distance between the pressure tap and the wall corner. Similarly, the fluctuating wind–rain induced pressure coefficients are larger in comparison to the wind-only pressure coefficients from the full-scale measurement and wind tunnel test. However, the coefficients decrease with the distance from the wall corner in the case of 80°–140° wind directions. In addition, it was found that Gamma distribution is a robust model to represent the probability distribution of the wind–rain induced pressure coefficients. High quality of pressure correlation was observed among three taps, regardless of the rainfall intensity. By contrast, the presence of driving rains slightly reduces the correlation of wind–rain induced pressure.

This study evaluates the aerodynamic characteristics and lateral displacements of two staggered buildings in a linked-building (LB) system. Particle image velocimetry and pressure measurements are employed, and the lateral displacement is evaluated using a 3-dimensional analytical model. When the gap distance between two non-linked buildings is small, the wind flows in a narrow jet, and a strong suction is generated on the inner surfaces of the two buildings, leading to a large cross-wind-induced response. However, the cross-wind-induced response is significantly reduced when a link is installed, because the suction forces generated from the buildings are in opposite directions and have a negative aerodynamic correlation. Conversely, with a large gap distance, the buildings at the front obstruct the wind blowing toward the rear buildings. Therefore, while the pressure distribution, wind-force coefficients, and wind-induced responses of the front and rear buildings show similar trends, the magnitude of impact on the front building is larger than that on the rear building. Installing a link is demonstrated to reduce the wind-induced response of the buildings in an LB system. However, the reduction in the along-wind-induced response is less than that in the cross-wind-induced response when the gap distance is small.

Wind tunnel tests have become one of the most effective ways to evaluate aerodynamics and aeroelasticity in bluff bodies. This paper has firstly overviewed the development of conventional wind tunnel test techniques, including high frequency base balance technique, static synchronous multi-pressure sensing system test technique and aeroelastic test, and summarized their advantages and shortcomings. Subsequently, two advanced test approaches, a forced vibration test technique and hybrid aeroelastic- force balance wind tunnel test technique have been comprehensively reviewed. Then the characteristics and calculation procedure of the conventional and advanced wind tunnel test techniques were discussed and summarized. The results indicated that the conventional wind tunnel test techniques ignored the effect of structural oscillation on the measured aerodynamics as the test model is rigid. A forced vibration test can include that effect. Unfortunately, a test model in a forced vibration test cannot respond like a structure in the real world; it only includes the effect of structural oscillation on the surrounding flow and cannot consider the feedback from the surrounding flow to the oscillation test model. A hybrid aeroelastic-pressure/force balance test technique that can observe unsteady aerodynamics of a test model during its aeroelastic oscillation completely takes the effect of structural oscillation into consideration and is, therefore, effective in evaluation of aerodynamics and aeroelasticity in bluff bodies. This paper has not only advanced our understanding for aerodynamics and aeroelasticity in bluff bodies, but also provided a new perspective for advanced wind tunnel test techniques that can be used for fundamental studies and engineering applications.

During landfall of Typhoon Haikui in Eastern China in 2012, ground level wind data were recorded using a smart monitoring system installed on JiuBao Bridge in Hangzhou, China. This article documents the mean flow and turbulence characteristics from data recorded during the storm. The results show that both turbulence intensity and gust factor decrease with the increase in the mean wind velocity. However, as the mean wind velocity increases, this trend gradually attenuates. The peak factor distribution with gust averaging time duration derived with the Typhoon Haikui data agrees well with the Durst curve. However, the longitudinal gust factor derived from the typhoon wind-speed record in this study is higher compared with the curves proposed by Durst and Krayer-Marshall. Analyses of the gust factor distribution with the turbulence intensity during the passage of the storm reveal a similarity to the empirical curves of Ishizaki and Choi. Results show that the relationship between lateral turbulence and gust factors can be well represented by a quadratic polynomial. Turbulence scale increased with mean wind velocity. The values of autocorrelation coefficients in longitudinal direction are larger than those in lateral direction. There has no obvious dependency of cross-correlation coefficients with mean wind velocity. In general, the wind characteristics in this study are shown to be very similar to those of winds under normal circumstance.

Understanding the characteristics of internal and external pressures on structures is important for structural design. This paper has experimentally observed internal and external pressures on long-span domes and investigated their non-Gaussian characteristics. Wind tunnel tests on internal and external pressure measurements for a single dome and two neighboring domes were performed. The distribution, non-Gaussian characteristics, and non-Gaussian peak factor of the internal and external wind pressure on the single dome were analyzed. After the results were validated, the distribution, non-Gaussian characteristics, and non-Gaussian peak factor of the internal and external wind pressure on the two neighboring domes under different wind attack angles (interference effect) were discussed. The results show that the characteristics of internal pressures on the single dome and the two neighboring domes are different from that of external pressures, and both the internal and external pressure show remarkable non-Gaussian characteristics. According to these characteristics, positive and negative areas of the internal and external pressure on the domes were defined, and the non-Gaussian peak factors were determined. This study has not only advanced our understanding on characteristics of internal and external pressure on long-span domes, but determined non-Gaussian peak factors that are used for structural design.

Bridge vehicle load is an important parameter that is relevant to the construction and maintenance stages of a bridge. In recent years, a large number of orthotropic steel deck bridges have been built in China, and it is urgent to establish a fatigue load model that reflects the actual traffic conditions of the bridges. This study has investigated the variation of vehicles over time on four grades of road (expressway, first-class highway, second-class highway and urban main road) according to the weight-in-motion (WIM) data. Subsequently, the statistical model was established in terms of speed, axle weight, and gross weight of vehicle (GVW) acting on the four grades of road. Finally, a fatigue load model of vehicles on the four grades of road was established based on a two-stage method. The results show that (1) the speed of vehicle on the four grades of road obeys the unimodal distribution; (2) the GVW of two- and three-axle vehicles on the four grades of road belongs to the t-distribution and the log-normal distribution, respectively; (3) the GVW of four- and five-axle vehicles on expressways is a finite mixed distribution, whereas the GVW of four- and five-axle vehicles on the remain three grades of road obeys the log-logistic and log-normal distribution respectively; (4) the GVW of six- and above axle vehicles on expressways and second-class highways obeys a finite mixed distribution with two variables, whereas that on first-class and urban main roads obeys the log-normal distribution; (5) the axle weight of standard fatigue vehicles differs remarkably on different grades of roads, which is difficult to describe the fatigue damage in a uniform standard fatigue vehicle.

The aerodynamic damping of forward and backward inclined prisms has been identified through a series of forced vibration wind tunnel tests. The test results show that the amplitude of vibration and reduced wind velocity both have a significant effect on the aerodynamic damping of the inclined prisms, especially at reduced wind speeds where von Karman vortex lock-in occurs. The effect of forward and backward inclination on the characteristics of aerodynamic damping in inclined prisms is dissimilar to a vertical prism, and the characteristics have been discussed in terms of the unsteady aerodynamic force and Strouhal number in this study. This study not only advances our understanding on aerodynamic damping of inclined prisms, but also provides values that can be used to estimate aerodynamics and aeroelasticities of inclined prisms.

The unsteady aerodynamic forces acting on a slender prism were investigated using a forced vibration technique. The prism was driven to oscillate by an actuator and the unsteady distributed pressures, under different wind velocities and oscillation amplitudes, were measured. The measurement was calibrated with respect to driving oscillation, aerodynamic force coefficient, as well as motion-induced force coefficient. Then, the generalized and local aerodynamic force coefficients and the motion-induced force coefficients of the prism, which are functions of reduced wind velocity and oscillation amplitude, were analyzed. It shows that the effects of structural motion on the coefficients are significant in the crosswind direction while the effects are slight in the along-wind direction. Furthermore, in the crosswind direction, the coefficients tend to increase with oscillation amplitudes at low wind speeds while they are at a quasi-steady state at high wind speeds. These characteristics were analyzed from the perspectives of generalized and pointwise spectra, force-response coherences and Strouhal numbers of the prism. The study advances the understanding of the effect of structural motion on three-dimensional prisms, which can be utilized to improve response predictions of the prisms.

It is common practice to transport heavy equipment via highway bridges. However, their strength may be insufficient in some situations and at present there are limited solutions applicable to long-span arch bridges. A matching load technique was thus developed by which vehicles with heavy cargo can pass over bridges by carefully placing calculated supplementary loads on the structures instead of applying strengthening. In this work, the relation between the strength of an arch section and the deviation of the thrust line from the neutral axis was analysed. It was found that arches have great reserves of strength if the deviation is minimised. Then, the crucial role that the eccentricity of the thrust on a section plays in current strength calculation algorithms was investigated. As a consequence, a criterion employed to examine qualitatively whether the section has adequate strength was established. Based on these analyses, the matching load technique was developed. The technique was validated on a 130 m long single-span arch bridge and was shown to provide a passage scheme to allow the safe transportation of a 400 t load.

In this paper, the Vortex Induced Vibrations (VIVs) of bridge deck sections of the Hong Kong-Zhuhai-Macao Bridge were investigated experimentally. Aeroelastic tests for the bridge deck of two scale ratios (1:20 model and 1:50 model) under different wind attack angles, wind speeds, and damping ratios were performed. Accessory and windbreak effects on the VIVs of the bridge deck were also carried out. The experimental results show that the accessory and windbreak tend to enlarge the VIVs of the bridge deck. Furthermore, the most unfavorable wind attack angle is 5°. At this attack angle and low damping ratios, the VIVs of the bridge deck are significant and much larger than the allowable value. In addition, the VIVs of the bridge deck decrease with increasing the damping ratios (Particularly, at large damping ratios, the VIVs were well suppressed). This study provides a guideline for the designs of long span flexible bridges on suppressing the VIVs of the bridges.

Extra long span rail transit bridges are generally slender and sensitive to excitations, and alignment control of the bridges should be conducted during construction. In this paper, the self-adaptive Kalman Filter (SKF) method was applied to the alignment control of the second longest rail transit bridge in the world. Each influential factor of the bridge alignment was firstly introduced. Then, the finite-element analysis and field tests of the bridge were carried out to obtain the influential factors that induced bridge cambers quantitatively. Combining with the cambers, the SKF method was applied to the alignment control of the bridge. Comparisons of the SFK-predicted alignment with the target alignment or the field measured alignment were carried out. Results show the SKF for alignment control of bridges is feasible and reliable.

Various structural failure modes exhibit great differences in occurrence probabilities, failure consequences and intrinsic characteristics, etc. Utilising these differences can enhance the effectiveness and efficiency of damage identification research, which has currently received little coverage. Therefore, a new idea, developing mode-specific damage detection methods, is suggested in the paper, with validation on beam structures. Firstly, structural behaviour was investigated from the perspective of stochastic traits and the structure design theory. It was concluded that developing damage detection methods for probabilistically dominant modes had potential to enhance the effectiveness of the identification significantly. Secondly, the strategy was applied to simply supported beams for the purpose of verification. When following the flexural mode, a major failure pattern of the beams, the structures demonstrated a very interesting feature – linearized deflection curves. Hence, damage severity and location indices were defined and an analytical model was built by quantifying the feature and then linking the indices to the curvature of the beams. Thirdly, experiments on reinforced concrete (RC) beams were conducted. The results showed that both the flexural mode and the characteristic of the linearized deflection curves were observed on all specimens; that there was a strong correlation between the damage severity index and the state of the defects on the beams; that the location indices corresponding to damaged and intact sections varied completely differently in quality and quantity. Thus, implementing the mode-specific strategy improves the specificity and efficiency of the damage identification dramatically.

In this paper, bridge alignment control with considering dynamic train loads was experimentally and theoretically investigated. Analytical process of bridge dynamics and the self-adaptive Kalman filter bridge alignment control method with considering the dynamic train loads were briefly introduced. The static measurement, the dynamic test, the field alignment measurement as well as the finite element analysis (FEA) of the second longest rail transit cable-stayed bridge in the world were carried out. Based on the results, the train dynamic load effect on the bridge alignment was obtained quantitatively. Subsequently, alignment control of the rail transit bridge with considering this effect using a self-adaptive Kalman filter method was analyzed. The results show that: (a) the dynamic train loads have effects on alignment control of the bridge and therefore cannot be neglected; (b) the self-adaptive Kalman filter method is applicable and reliable for alignment control of bridges during construction. The analytical method and whole process contribute to develop a related specification and further engineering applications.

This study proposes a method to predict the shrinkage strain of concrete restrained by studs and steel plates. This method is based on the capillary tension theory. Experiments were conducted to investigate the pore structures and shrinkage strains of concrete specimens with steel plates of various thicknesses and materials, and studs of different diameters, heights, and quantities. The studs and steel plates significantly affected the pore structures of the concrete specimens; the values of the parameters of the specimens increased linearly as the restraining effects of the studs and steel plates increased. The coordinated deformation and decreased capillary stress of the constrained members lead to the shrinkage reduction and deformation of concrete restrained by studs and steel plates. The proposed method was found to be effective in predicting the shrinkage strain of concrete under stud and steel-plate restraints.

The non-wind-induced additional nonlinear damping and stiffness of a spring-suspension system (under wind-off conditions) would significantly influence the prediction of aeroelastic response. This study proposes a forced vibration technique to identify the non-wind-induced nonlinear damping and stiffness of both vertical and inclined prisms. The forced vibration-pressure test was performed to observe the non-wind-induced pressure at first. It was observed that the pressure was remarkably affected by the amplitude of structural oscillation, and the corresponding non-wind-induced force is thus nonlinear. A procedure is then proposed to identify the non-wind-induced nonlinear damping and stiffness of the prisms from the tested nonlinear forces. The results yielded by the proposed procedure in terms of a vertical prism has been verified by comparing the response predicted by the unsteady aerodynamic force with/without the non-wind-induced nonlinearities with the measured response. Moreover, the non-wind-induced nonlinearities of inclined prisms have been tested by using the proposed forced vibration technique, which also suggests a mathematical model of the identified results for the purpose of convenience.

A mathematical model to quantify the unsteady self-excited forces (USEFs) acting on a slender prism was developed, to address the shortcomings of the classical quasi-steady theory employed to predict the galloping instability of slender prisms. The unsteady aerodynamic force and galloping response of a prism were measured from a hybrid aeroelastic-pressure balance (HAPB) that can synchronously observe unsteady pressure and aeroelastic response. It was found that the galloping response predicted by the unsteady aerodynamic force is in close agreement with the experimental result whereas the quasi-steady theory cannot predict the galloping instability. According to an energy equivalent method, the unsteady aerodynamic force was quantitatively decomposed into three components: an aerodynamic damping force component, an aerodynamic stiffness force component and a residual force (buffeting force) component. Subsequently, a nonlinear mathematical model for the USEF which is a 1st-order polynomial function representing the aerodynamic damping and stiffness force components, was established. The results indicated that the 1st-order model was effective in predicting the galloping response of the prism. It was also demonstrated that the model can be used to predict the galloping instability of prisms with different mass-damping ratios.

Structural health monitoring (SHM) technology for surveillance and evaluation of existing and newly built long-span bridges has been widely developed, and the significance of the technique has been recognized by many administrative authorities. The paper reviews the recent progress of the SHM technology that has been applied to long-span bridges. The deployment of a SHM system is introduced. Subsequently, the data analysis and condition assessment including techniques on modal identification, methods on signal processing, and damage identification were reviewed and summarized. A case study about a SHM system of a long-span arch bridge (the Jiubao bridge in China) was systematically incorporated in each part to advance our understanding of deployment and investigation of a SHM system for long-span arch bridges. The applications of SHM systems of long-span arch bridge were also introduced. From the illustrations, the challenges and future trends for development a SHM system were concluded.

The plastic-damage factor of concrete structures is important for structural load-capacity assessment, while it has not been determined properly. In this article, two methods perspectively based on the strain equivalent principle and Sidiroff energy equivalent principle are proposed to determine the plastic-damage factor of the concrete uniaxial constitutive relation in a specification. Both of them were applied to a finite element analysis model of a simply-supported beam for nonlinear load-capacity analysis. The load-capacity experiment of the beam was carried out in unison. From the comparison of the result obtained by the energy equivalent principle method coincides better with the experimental result, which suggests that the energy equivalent principle method is reasonable and applicable. Therefore, the factor could be recommended for further consideration in specification and finite element analysis calculations.

Bridges are an important component of transportation. Flutter is a self-excited, large amplitude vibration, which may lead to collapse of bridges. It must be understood and avoided. This paper takes the Jianghai Channel Bridge, which is a significant part of the Hong Kong-Zhuhai-Macao Bridge, as an example to investigate the flutter of the bridge deck. Firstly, aerodynamic force models for flutter of bridges were introduced. Then, wind tunnel tests of the bridge deck during the construction and the operation stages, under different wind attack angles and wind velocities, were carried out using a high frequency base balance (HFBB) system and laser displacement sensors. From the tests, the static aerodynamic forces and flutter derivatives of the bridge deck were observed. Correspondingly, the critical flutter wind speeds of the bridge deck were determined based on the derivatives, and they are compared with the directly measured flutter speeds. Results show that the observed derivatives are reasonable and applicable. Furthermore, the critical wind speeds in the operation stage is smaller than those in the construction stage. Besides, the flutter instabilities of the bridge in the construction and the operation stages are good. This study helps guarantee the design and the construction of the Jianghai Channel Bridge, and advances the understanding of flutter of long afterbody bridge decks.