Monitoring data-based traffic load effect model statistical analysis for arch bridge suspender

The bridge health monitoring system collects bridge information through sensors and transmits it to the data center, and realizes real-time monitoring and early warning of bridges through data processing and analysis. To improve the bridge health monitoring system, this paper summarizes and studies the traditional bridge health monitoring system, and introduces the method of selecting and optimizing the layout of bridge health monitoring sensors in detail. By comparing different transmission systems of bridge health monitoring, the advantages and disadvantages of each system are obtained. Finally, a 5G-based bridge health monitoring system is proposed, which can provide a reference for improving the problems of high delay caused by insufficient data transmission bandwidth in the monitoring system.

To provide benefit for design, rating, evaluation and management of signature bridges, site-specific extreme wind speeds, structural temperatures, and traffic load effects of a long-span cable-stayed bridge were estimated using relatively long-term structural health monitoring (SHM) data and compared with respective design values in this paper. The generalized Pareto distribution was adopted and briefly introduced to predict the extreme values in consideration of its advantage in making full use of limited measurement data available. The configuration and characteristics of the 3rd Nanjing Yangtze River Bridge and its SHM system were then presented. The extreme wind speed at the deck level and the four extreme temperatures of the bridge were estimated and compared with the corresponding design values. After a brief introduction to the simulation of traffic load effects, five extreme traffic load effects were finally estimated and compared with the design ones. The comparative results showed that the site-specific extreme wind speed, uniform girder temperature change, and five traffic load effects are all lower than the respective design values. The site-specific extreme vertical and transverse girder temperature differences and the site-specific extreme tower temperature difference were, however, larger than the respective design values.

The traffic load has grown significantly in recent years, which could pose a threat to the service safety of existing bridges. Thus, evaluating the actual traffic load effects on bridges using actual traffic data is an urgent task. This study presents a framework for extrapolating maximum dynamic traffic load effects on long-span bridges using site-specific traffic monitoring data. The framework involves traffic-bridge interaction analysis and probabilistic modeling of extreme values. The weigh-in-motion measurements of a heavy-duty highway were utilized to simulate stochastic traffic loads. Case studies of two long-span cable-supported bridges based on weigh-in-motion measurements were undertaken to demonstrate the effectiveness of the proposed framework. It was concluded that Rice’s level-crossing approach can capture both the dynamic and probabilistic characteristics of traffic load effects, and thus provides a reasonable extrapolation. The amplification factors for the cable-stayed bridge and the suspension bridge are 5.9% and 3.6%, respectively. For a longer-span bridge, the dynamic effect for extrapolation is weaker, but the effect of traffic volume growth seems more significant.

With the steadily growing of global transportation market, the traffic load has increased dramatically over the past decades, which may develop into a risk source for existing bridges. The simultaneous presence of heavy trucks that are random in nature governs the serviceability limit for large bridges. This study investigated probabilistic traffic load effects on large bridges under actual heavy traffic load. Initially, critical stochastic traffic loading scenarios were simulated based on millions of traffic monitoring data in a highway bridge in China. A methodology of extrapolating maximum traffic load effects was presented based on the level-crossing theory. The effectiveness of the proposed method was demonstrated by probabilistic deflection investigation of a suspension bridge. Influence of traffic density variation and overloading control on the maximum deflection was investigated as recommendations for designers and managers. The numerical results show that the congested traffic mostly governs the critical traffic load effects on large bridges. Traffic growth results in higher maximum deformations and probabilities of failure of the bridge in its lifetime. Since the critical loading scenario contains multi-types of overloaded trucks, an effective overloading control measure has a remarkable influence on the lifetime maximum deflection. The stochastic traffic model and corresponding computational framework is expected to be developed to more types of bridges.

Eighteen certified flight instructors from the University of Illinois Institute of Aviation participated in an experiment exploring the design of the Cockpit Display of Traffic Information (CDTI) for free flight. Pilots flew a sequence of flight scenarios to compare the effects of traffic load, dimensionality, and a vertical profile orientation on maneuver frequency, safety, and maneuver efficiency. Climbs and descents were found to be more frequent than other maneuvers. Both the rear-view and 3D displays were safer in terms of predicted conflict avoidance than the side-view display. Climbing maneuvers were more safely implemented with the rear-view and 3D displays than with the side-view display. The lateral efficiency of climbing maneuvers was highest with the rear-view display. Altitude maintenance of lateral/vertical maneuvers was highest with the side-view, then the rear-view, and then lowest with the 3D display. Airspeed efficiency of airspeed maneuvers was highest with the rear-view display. These findings suggest that a rear-view coplanar CDTI may be preferable to either a side-view coplanar or 3D display.

Wireless ad hoc networks are a collection of mobile nodes spreading over a defined geographical area, enabling realtime collaborative applications such as push-to-talk and VoIP. Unfortunately, wireless ad hoc networks suffer from limited bandwidth and QoS constraints. A proposed eXplicit MultiCAST (XCAST) based routing protocol (P-XCAST) is presented in this paper to support team-based communications in wireless ad hoc networks. XCAST is well suited for supporting a large number of small groups effectively, in comparison with multicast based protocols. However, since XCAST was initially designed for wired networks, it was not optimized for wireless ad hoc network use. The proposed P-XCAST protocol enhances XCAST for ad hoc network use by having a Group Route Request mechanism to build the network topology, and route data packets containing the list of destinations for a given group in the XCAST header, by classifying the destinations according to similarities in their next hop neighbors and hop counts. A single data packet is XCASTed in lieu of sending n Unicast data packets to n destinations with the same next hop neighbor. In this paper, P-XCAST was tested using different traffic load values that are used with different codec to investigate its performance in various group sizes. The results of simulation show better QoS performance compared with other routing protocols.

The authors' paper in the Proceedings of the ASCE Pipelines 2003 Conference described use of the Cambridge University geotechnical centrifuge to simulate the loading sequence and possible deterioration mechanisms of a sewer and its soil surround, both before and after renovation by lining with cured-in-place pipe (CIPP) or 'close-fit' thermoplastics pipe. The preliminary results reported referred to tests using a sand surround placed at the same initial density, and a single model liner/host pipe assembly with a consistent initial lack of fit, in which the main variable was the sequence of application of a series of extreme deterioration events in the soil (formation and collapse of large voids) and the host pipe (complete loss of both flexural and compressive ring stiffnesses). The effects of traffic loading on both deep and shallow buried lined pipes were also examined. This follow-up paper describes the outcome of further centrifuge tests in which both the initial density of the soil surround and the initial annular gap between liner and host pipe were substantially reduced in order to simulate, in conjunction with the extreme soil and host pipe deterioration events previously applied, the worst practically conceivable case for transfer of soil and traffic loads to a close-fitting, flexible sewer liner. Some basic principles and the implications of the test results for liner design practice are also considered.

The variation in road cross slope with service life affects the pavement drainage and has an adverse effect on vehicle operation safety. This paper describes a cross-slope variation prediction method influenced by the coupling effect of traffic load and soil consolidation, considering characteristics of embankment to cover the shortage for insufficient consideration of compacted embankment. First, the traffic load-induced settlement equation of a highway on soft soil foundation was introduced, which considers the effects of traffic load stress, confining pressure, soil structure, strength weakening and cyclic loading times on different positions along the cross-section. Then, the finite element model of a highway on soft soil foundations under soil consolidation is established, considering the influence of soil seepage. Finally, predictions of long-term settlement and cross-slope variation generated by coupling action of traffic load and soil consolidation were carried out with contrastive analysis with measured data. We find the following: (1) the long-term settlement was mostly from the consolidation of natural soft subsoil, while the cross-slope variation was mainly affected by traffic load; (2) variation in the cross slope of highway in soft soil areas mainly occurs within 1 year of operation. The effect of passenger cars and trucks on cross-slope variation shows diametrically opposite results, as the passenger car lane decreases while the truck lane increases; (3) the relative error of the cross-slope variation prediction results with the measured data are 2.86% and 2.5% for the left and right lane cross slopes, respectively.

A further development of the synchronous array method (SAM) as a medium access control scheme for large-scale ad hoc wireless networks is presented. Under SAM, all transmissions of data packets between adjacent nodes are synchronized on a frame-by-frame basis, and the spacing between concurrent cochannel transmissions of data packets is properly controlled. An opportunistic SAM (O-SAM) is presented which allows concurrent cochannel transmissions to be locally adaptive to channel gain variations. A distributed SAM (D-SAM) is discussed that schedules all concurrent cochannel transmissions in a distributed fashion. For networks of low mobility, the control overhead required by SAM can be made much smaller than the payload. By analysis and simulation, the intranetwork throughput of O-SAM and D-SAM is evaluated. The effects of traffic load and multiple antennas on the intranetwork throughput are studied. The throughput of ALOHA is also analyzed and compared with that of O-SAM and D-SAM. By a distance-weighted throughput, a comparison of long distance transmission versus short distance transmission is also presented. The study of D-SAM reveals an important insight into the MSH-DSCH protocol adopted in IEEE 802.16 standards.

Long-term indirect monitoring system for short and medium span bridges

For the traditional resistance strain sensor's shortage,for example,their stability,durability and monitoring scorpe could not satisfied the requirement of bridge monitoring system,put forward to adopt advanced fiber-optic bragg grating sensor and its technology to build up the bridge health monitoring system.Analysed the application scope and aim of difference kinds of fiber bragg grating sensors used, including stress strain sensors,temperature sensors,crack sensors and testing force ring sensors.According to the key construction sections as the project designed,expatiated their specific installation methods and construction craftwork in Wuhan Yangtze River 2th bridge.It formed distributed fiber sensing network of bridge with large-scale located fiber-optic bragg grating sensors, and pointed out the becareful prodeeding when to link no more than twenty sensors to one fiber for the demodulator precision.Discussed how to construct the data acquisition system and its function via the sensors and their demodulator.One fiber of the linked sensors connected to one channel of the demodulator and all together reached sixteen channels.The demodulator were connected to the switch through rj45 interface and communicated with the acquisition server.Designed the software program of data acquisition software system and the database,which used the Sqlite of the embed database to storage the configure information and receive the data through the TCP/IP protocol.It has been build a bridge health monitoring system base on fiber bragg grating technology.

Bridge vibration frequency is a measure of the overall state and structural damage will inevitably lead to changes in frequency. Based on this approach, we realized the bridge health monitoring system, introduced the bridge health monitoring system design approach, the data collection process and data analysis. Test proved that the vibration frequency of the bridge on the health status of the bridge. By the system design process and experimental results, from the experimental point of view, we can assess the overall state of the bridge model. Through this test, we can carry out health monitoring of bridge large-scale structures. It is important to bridge health monitoring.

Health monitoring has been one of particular concerns of the engineering community in Japan. Effective monitoring, reliable data analysis, rational data interpretation and correct decision making are challenging problems for engineers who specialized in bridge monitoring field. In this paper, the status of health monitoring of long-span bridges in Japan is briefly reviewed. The monitoring system was developed to be a reliable device to observe the bridge in earthquake and/or typhoon accurately, besides have a self-check function to sense the disorder of the system itself. Current practices in health monitoring of bridges are represented by the example of Akashi Kaikyo Bridge monitoring system. The reliability of the current monitoring system is confirmed by comparing the analyzed simulation results and field-measured results. Furthermore, a newly developed monitoring system is proposed to provide information for structural health maintenance, so called Monitoring Based Maintenance (MBM). This monitoring system is easily accessible, economically feasible and durable through efforts in development of innovative sensors and new generation of automated remote monitoring technology.

Bridge health monitoring (BHM) technology has been widely accepted as a powerful tool to assess structural performance and has moved from research to practice. Driven by the enormous demand of ensuring bridge safety, the application of BHM technology is particularly active in China and has become an emerging industry in the civil engineering community. It is a common belief among civil engineers that the development and implementation of industry standards will be of paramount importance in guiding the healthy development of BHM and increasing the transfer of professional knowledge and techniques to practical applications. This paper presents a comprehensive overview of the standardization construction and development trend for BHM in China. The achievements, characteristics, and challenges of China’s bridge construction are first introduced. Then, the existing problems of BHM and the necessity of constructing the standardization system for the BHM industry are discussed. Following that, these standards published for guiding BHM system design, construction, management, and maintenance, especially sensor selection, sensor placement, sensor installation, data transmission, data storage, data processing, and early warning, are outlined. Finally, work requiring further efforts in the near future is drawn.

A self-powered bridge health monitoring system driven by elastic origami triboelectric nanogenerator