Fatigue damage analysis of epoxy asphalt pavement for steel bridges considering coupled effects of heavy load and temperature variations

To investigate the fatigue damage of epoxy asphalt pavement(EAP)under a heavy load and a d temperature load,the load-figure of the heavy load on the steel bridge deck pavement(SBDP)was simulated first,and the temperature distribution of SBDP during the temperature-fall period in winter was also calculated.Secondly,t e moving heavy load coupled W t the most unfavorable temperatre load was applied to the SBDP,and the tensile stress on the top of SBDP was calculated.Finally,the fatigue damage of EAP was evaluated considering the extreme situation of heavily overloaded and severe environments.The results show that botte heavy load and the temperature load during t e temperature-fall period c n increase the tensile stress on the top of SBDP significantly.In the exteme situation of heavily overloaded and severe environments,a fatigue crack is easily generated,and thus the SBDP should avoid t e coupling effects of the heavy loadand the temperature load in winter.

SYNCHRONOUS EFFECT OF SLIPPING HEAVY LOADS ON RO-RO SHIP ROLLING IN WAVES

Common effect of wave and slip of internal vehicles will make rolling of the roll-on ship serious. This is one of the important reasons for overturn of ro-ro ships. The multibody system with a floating base is composed of ro-ro ship and slipping vehicles. Takes the rolling angle of the ship and the transverse displacements of the slipping vehicles on desk as freedoms. Making use of the analysis of apparent gravitation and apparent buoyancy, the wave rolling moment is derived. By means of dynamic method of multibody system, dynamic equations of the system are established. Taking a certain channel ferry as an example, a set of numerical calculation have been carried out for rolling response of the multibody system with a floating base of a ro-ro ship and displacements response of the slipping vehicles under common effect of free slipping vehicles and wave, and a conclusion has been drawn that the motion of the numerous free slipping heavy loads will trend to be synchronous under restraining of the side-wall bulkhead with time because of repeated collision.

Cost Impact of Increasing Heavy Vehicle Loads on Bridges

This study aimed to investigate the cost impact of meeting the increase in freight demand by doubling the truck weight （AS 1 ）, doubling the traffic volume （AS2）, or legalizing a new-proposed-truck of 97-kip weight instead of the currently legal 80-kip truck （AS3）. The State of Michigan＇s average daily traffic database of year 2001 has been used as a case study. The study was applied only on the very common US Bridge with RC （reinforced concrete） deck over steel girder. Sampling criteria also includes the age of the bridges. The study covered the four-cost-impact categories provided by the NCHRP （National Cooperative Research Program）. The current truck weight and double traffic volume （AS2） show the best scenario to meet the increase in freight demand. However, doubling the truck weight with the current traffic volume （AS 1） was the worst scenario. The use of the proposed 97-kip truck with the current traffic volume （AS3） compromises both, meeting the increase in freight demand and the cost impact.

Application of semi-analytical finite element method to analyze asphalt pavement response under heavy traffic loads

Accurate assessment of the impact of heavy traffic loads on asphalt pavements requires a computational model which is able to calculate the response of the pavement fast and precisely. Currently the most finite element analysis programs based on traditional methods have various limitations. A specific program SAFEM was developed based on a semi-analytical finite element method to overcome the problems. It is a three-dimensional FE program that requires only a two-dimensional mesh by incorporating the semi- analytical method using Fourier series in the third dimension. The computational accuracy and efficiency of the program was verified by analytical verification previously. The experimental verification is carried out in this paper and the results show that the SAFEM is able to predict the mechanical responses of the asphalt pavement. Using the program SAFEM, the impact of heavy traffic loads was analyzed in terms of stress and strain dis- tribution, surface deflection and fatigue life. The results indicate that if the asphalt pave- ment is subjected to the heavy traffic load more, the thicknesses and stiffness of the pavement structural layers should be increased adequately in order to support the surface deflection, The compressive stress in asphalt binder course is relatively large and increases more significantly compared with that in the other asphalt layers when the axle load becomes larger. With comparison of the predicted fatigue life, the increase of the axle load will lead to the destruction of the asphalt pavement extremely easily.

Assessment of Long-Time Behavior for Bridge Girders Retrofitted with Fiber Reinforced Polymer

Maintaining both the safety and serviceability of deteriorating highway bridge networks necessitates suitable BMS （bridge maintenance system） tools that can maximize cost effectiveness. Numerous experiments have been conducted to detect the long-term mechanical properties of the epoxy resin materials used in FRP （fiber reinforced polymers） strengthening and maintenance technique. Experiments were used to develop a short-term test and construct a model that can reliably predict the long-term behavior of epoxy resin. Furthermore, FEA （finite element analysis） models were developed, using the ANSYS software, to simulate three unstrengthened and FRP strengthened prestressed concrete girder bridges of different configurations. Models simulate the original and aged properties of construction and retrofitting materials under the application of AASHTO （American Association of State Highway and Transportation Officials） fatigue truck and a site-specific fatigue truck in different scenarios. These models were used to develop the bridge performance chart for the capacity of the bridge, with and without strengthening interventions, as a BMS tool. The results show an immediate significant improvement in the concrete tensile stress with the intervention of FRP strengthening.

A Baseline Study on the Quality and Safety of Consumption of a Pest Species(Sarotherodon melanotheron)in Bataan,Philippines:Basis for Its Productive Utilization in the Fisheries Sector

The baseline study profiled Black-chin Tilapia(Sarotherodon.melanotheron),a fish farm pest species in Bataan,Philippines,in terms of yield(processing and fillet),proximate composition(moisture,ash,crude fat,and crude protein),heavy metal load(cadmium[Cd],lead[Pb],arsenic[As],and mercury[Hg]),and microbial count(aerobic plate,Escherichia coli,and Staphylococcus aureus counts).The purpose was to establish the species’safety and quality for consumption and potential utilization in the processing of higher value fishery products.A completely randomized experiment using two factors,fish size(standard and small sizes)and collection season(dry and wet seasons),was employed.The collected data were also compared against food consumption and processing standards and/or previous reports on more valuable species.The results showed that the species has a comparable yield and mineral load with the more popular farmed Nile Tilapia(Oreochromis niloticus).It has high moisture and protein compositions.It is a lean fish that can serve as a cheaper functional raw material for processed fishery products.Moreover,the results showed that the species have no As,Cd,and Pb contamination,although traces of Hg,far below the permissible limits,were detected.The Hg load varies across collection season and fish maturity suggesting its manageability.For the microbial contents,the species’aerobic plate,Escherichia coli,and Staphylococcus aureus counts were far below the standard limits,although best post-capture practices are still suggested due to the kind of microbial parameters measured.It was concluded that the Sarotherodon melanotheron infesting Bataan farm ponds can be consumed safely and has the quality of potential raw material for processed fishery products.However,further information is still needed to establish the best post-capture handling on the species.Also,more studies must be done to determine the impact of storage and processing on its stability.