Yiqiang Xiang

Dynamic behavior of cable-stayed beam with localized damage

An elastic continuous model is presented for the inclined cable with damage which is described as reduction of the axial stiffness. The damage effect on the static configuration of the cable under self-weight is investigated through a numerical solution. Hamilton’s principle is then employed to derive the governing equations for the in-plane dynamic motion of the cable-stayed beam with cable damage. The linear eigenmodes are obtained via the method of reverberation-ray matrix after a standard condensation procedure. A single-degree-of-freedom nonlinear model is obtained by the single-mode discretization. The homotopy analysis method is then successfully applied to get the frequency-amplitude relationship, which enables the influence of cable damage on the nonlinear dynamic behavior of the system to be characterized.

Optimizing Model of Curb Parking Pricing Based on Parking Choice Behavior

Abstract Curb parking is an indispensable part of urban public parking system. A reasonable curb parking pricing scheme makes contribution to improve the use efficiency of curb parking and to reduce traffic congestion. This paper analyzes the parking choice behavior from the micro-aspects, and the choice utility function is established to combine with the travel time, search time, waiting time, access time, and parking pricing. Through the utility function, the Probit-based parking choice behavior model is formulated. Based on that, the curb parking pricing model is proposed by considering the constrained conditions. Finally, the incremental assignment algorithm of the model is designed and the model is applied to the parking planning of Tonglin, China. The results show that the proposed model has practicality and reliability in the practical operation.

Effects of Ordinary Tension Reinforcement on the Response of Beams with Unbonded Tendons

This paper describes an analytical investigation of the flexural response of unbonded prestressed beams and the ultimate stress increase in unbonded tendons, with particular emphasis on the effects of bonded ordinary tension reinforcement. A numerical model, based on the finite element method incorporating an arc-length solution technique, is developed to predict the entire nonlinear response of concrete beams prestressed with unbonded tendons. The reliability of the proposed analysis is verified by comparing the analytical predictions with the experimental results. Two parameters relating to bonded ordinary tension reinforcement are analytically investigated. The analytical results show that an unbonded prestressed concrete beam without any ordinary tension reinforcement exhibits very poor behaviour. However, with the minimum amount of ordinary tension reinforcement provided, the flexural behaviour of the beam is greatly improved. The variable yield strength of ordinary reinforcement in combined reinforcing index is inappropriate in its current form since the calculated prediction is inconsistent with the actual trend of the variation of ultimate stress increase in tendons.

Output-Only Damage Detection of Steel Beam Using Moving Average Filter

This paper provides a simple and direct output-only baseline-free method to detect damage from the noisy acceleration data by using Moving Average Filter (MAF). MAF is a convolution approach based on a simple filter kernel (rectangular shape) that works as an averaging method to smooth signal and remove incorporated noise. In this paper, a method is proposed to employ MAF to smooth acceleration signals obtained from a series of accelerometers and determine the damage location along a steel beam. To verify the proposed method, a simply supported beam was modelled through a 3D numerical simulation and an experimental model under a moving vehicle load. The response acceleration data was then recorded at a sampling frequency of 500 Hz. Finally, damage location was identified by applying the proposed method. The results showed that the proposed method can accurately estimate the damage location from the acceleration signal without applying any frequency filtering or baseline correction.

Bridge Design Basic Wind Speed Based on the Joint Distribution of Wind Speed and Direction

Based on the method of separation of wind speed and direction variable, considering the wind direction frequency function, ascending order to calculate the probability of the actual distribution of the sample, extreme type Ⅰ (Gumbel) and three parameters of extreme type Ⅱ (Frechet) and extreme type Ⅲ (Weibull) probability distribution to fit the sample, this paper has analyzed the weather station observations of 34 consecutive years of the joint distribution of wind speed and direction near to a huge bridge, gained the basic design wind speed in different directions, comparatively analyzed the impact of the sampling interval of change on the basic wind speed as well. The results shows: wind speed in different directions at the same location or different sampling intervals samples of the wind speed sample may be subject to different types of extreme value distribution, should separately fitting; different wind direction frequency of extreme wind speed occurrence and the basic wind speed there are certain differences, taking into account the joint distribution of wind speed and direction is necessary to determine the design basic wind speed of the bridge, and will be conservative without considering the joint distribution; for the same sample wind speed matrix, the shorter the sampling intervals, the optimal distribution of the higher probability model fitting precision, the smaller the basic wind speed, the more economic and reasonable the results.

Study on Health Monitoring System Design of Cable-Stayed Bridge

Large civil structures such as cable-stayed bridge should be periodically inspected to ensure structural integrity. Taking the main span of Chaibu Bridge as an engineering background, this paper summarizes the monitoring strategies and designs of the structure health monitoring system. The whole layout of sensors and the components of the structure health monitoring system are discussed. The study shows the structural health monitoring systems can offer valuable information in evaluating structural integrity, durability and reliability, and ensure optimal maintenance planning and safe bridge operation.

Revised Model of Chloride Diffusion in Concrete Bridge by Considering Complex Action of Load and Chloride Binding Capacity

Coastal concrete bridges will suffer from deterioration of RC structural performance and resistance attenuation because of the chloride penetration and other environment factors. This article discusses current different chloride diffusion models and puts forward the revised model of chloride diffusion in concrete bridge by considering the complex action of load influence and chloride-binding capacity. Comparison of numerical predicted values and relative experimental tests show the presented chloride diffusion model to be more accurate. It provides a theoretical basis for the performance assessment and accurate prediction of the remaining life of highway concrete bridges.

Accurate FEM of Steel-Concrete Composite Box Girder Bridge for Damage Identification Based on Dynamical Experimental Study

Based on the results of experiment, this paper discusses about the updating and validation of accurate finite element model for damage identification of the steel-concrete composite box girder bridge. Taking a 5 meters long steel-concrete composite box girder bridge as the research object and the finite element model is established. By means of scale model test the updating of the accurate finite element model has been completed and validation is confirmed.

Behaviour Analysis of Prestressed Concrete Deck-Tied Arch Bridge

The prestressed concrete deck-tied arch bridge doesn’t only have a long span, good appearance and economy, but also have the characteristics of low requirements to the foundation. It changes traditional tied arch bridge into deck-tied arch bridge, which looks like sunflower-shaped arch and prestressed steel strands are embedded in box girder on the top of the arch. Taking Yingbin Bridge as engineering background, the reasonable analysis model was established and behaviour of the bridge under design load was analyzed. The results shown that the design project is reasonable, prestressing force embedded in box girder can balance horizontal thrust in arch bridge effectively, improving the internal force of the main arch ring.

Research on Monitoring and Control for Suspender Cable Tension of Half-Through Concrete Filled Steel Tube Arch Bridge

The measurement accuracy of the cable tensions in the hanger rods of concrete filled steel tube arch bridges is important for the correct evaluation of bridges condition. Based on Jinpan Bridge-a half through concrete filled steel tube arch bridge with 80 m span in Tiantai, it was put forward the vibration frequency method for testing and evaluate suspender tensions with the help of analysis vibration characters of the suspender. The precision of cable force calculation formula was verified after comparing the practical tension with the designed tension obtained from tension jack method. Then, according to the test results and values predicted by the presented cable force calculation formula, the cable tensions were adjusted. Cable tension test results in the finished bridge show that this method is feasible.