Advanced Materials Research Vols. 538-541

Abstract: In order to evaluate single tower composite girder Cable Bridge actual bearing capacity and working property on design using load, a single-tower composite girder cable-stayed bridge is taken as an example, by means of static load test, dynamic load test, reasonably measures evaluates the single tower composite girder cable-stayed bridge's bearing capacity. The static load test measure static properties of bridge structure (static strain, static deflection, etc.), dynamic load test, measure the dynamic properties of bridge structure (vibration frequency, damping, forced vibration amplitude, impact coefficient, etc.). Results show that the rigidity strength integrity and dynamic characteristics of bridge structure are favorable; the structure’s bearing capacity is favorable.

Abstract: Engineered fiber reinforced cementitious composite (ECC) can significantly improve the seismic performance and durability of concrete structures, which has pseudo strain hardening and multiple cracking performances. Through 32 groups of 192 specimens for compressive strength of ECC, the orthogonal test study on the cube compression failure process, and further research on water binder ratio, fiber content by volume, fly ash content and sand binder ratio of 4 kinds of factors on the size effect of ECC cube compressive strength. The test result shows that: PVA fiber content increases, ECC compressive toughness is improved obviously; water binder ratio and fiber content are the main factors which affect the ECC compressive strength and size effect. When water binder ratio decrease, the compressive strength of ECC materials improve and size effect coefficient increase. Fiber content increase, the compressive strength of test block increase and the size effect coefficient increase. Through the bending tests, we know that: the fiber content by volume increases, the ECC flexural strength of the composite increases gradually.

Abstract: New-style ketchup packaging composite board box is an important technical innovation in ketchup packaging and has broad market prospect because of its economic and recyclable. Some tests including material property test and assembly property test have been done on the new-style composite board box. Different thickness boards such as 20mm, 25mm and 28mm have been tested in the paper. The results show that new-style composite board box can meet the requirements of ketchup packing.

Abstract: Stay cables of long span cable-stayed bridges are easy to vibrate under wind or wind/rain loads owning to their very low inherent damping. To install cable dampers near to the anchorages of cable has become a common practice for cable vibration control of cable-stayed bridge structures. In this study, the behaviors of a nonlinear frictional type of damper were investigated. The equations of motion of a cable with a friction damper were derived by using a lumped mass model. Then by introducing modal transformation, the analytical solution for the motion equations was obtained. The results show that the friction damper evokes linearly decaying of free vibrations of the cable as long as the damper does not lock the cable. The modal damping ratio of cable with the friction damper is strongly amplitude dependent. Calculation of modal damping ratio can be simplified using control parameter and the maximum modal damping ratio can be obtained. A universal estimation curve is proposed that is similar to linear viscous damper. These studies could provide design basis for the vibration mitigation of stay cables using nonlinear friction.

Abstract: Calculation model of the varying stress responsing to dynamic road in two degree freedoms is deduced from the moving load effecting on stress change in asphalt pavement structure. There are some constraint conditions and objective factors in varying stress response. Aiming at the impact of qualitative factors which are difficult to quantify, according to specialist experience, system of multi-Agent was established by amending the Agent of knowledge containers and social relationships. Multi-intelligence Agents had an ability of self-adjustment by accommodating itself to environment changes. Then the dynamic task can be solved by intelligent Agent. It reflects objectively the pressure state of the pavement and definitely specific cause for early danage in pavement. This work can provide theoretical guidance for further study the relations between vehicle and pavement.

Abstract: Paper deal with influence of on service life and degradation processes at construction of bridge piers and abutments before and after repair actions. Monitored dependencies are then reflect on degradation curves each for a singles construction characteristics (compression strength of concrete, degradation of surface, volume of carbonatation etc.) Pursuant to long-term monitoring of records from bridge piers surface diagnostic we have to be able to unite the records and use them for silicate coatings degradation dependence on bridge piers and abutments and laboratory simulated degradation.

Abstract: Local damages such as knots, decay, and cracks can be translated into a reduction of service life due to mechanical and environmental loadings. In wood construction, it is very important to evaluate the weakest location and detect damage at the earliest possible stage to avoid the future catastrophic failure. In this study, modal testing was conducted on wood beams to generate the first two mode shapes. A novel statistical algorithm was proposed to extract the damage indicator by computing the modal flexibility curvature before and after damage in timbers. Different damage severities, damage locations, and double damages were simulated by removing mass from intact beams to verify the algorithm. The results have shown that the proposed statistical algorithm is effective and suitable to the designed damage scenarios. The proposed algorithm can qualitatively identify the damage existence and its location although there is no linear correlation between damage indicators and damage severities. The peak values of the damage indicators increase when the losses of the second axial moment of area increases. It is also reliable to detect multiple damages.

Abstract: In order to study the application of laser cladding and laser shock processing (LSP) combinatorial treatment technology, the laser cladding samples of TC4 titanium alloy was shocked by pulse laser, then the surface residual stress, the fatigue life were compared with those without LSP in this paper. High cycle tension-compression fatigue tests were carried out in laser cladding titanium alloy before and after LSP treated. The results indicate that LSP treatment can improve the high cycle fatigue endurance limit of laser cladding titanium alloy effectively. The nano-crystal grained surface layer with residual compressive stress makes great contributions to the improvement in fatigue properties of titanium alloy.

Abstract: The laser shock processing(LSP) is a new surface treatment technique that induce a significant compressive residual stress field on the metal and alloys. The developed compressive stress field is beneficial to improve surface properties such as fatigue, wear, and corrosion. To improve the understanding of the shock process, investigation into the physical processes and its variability involved is necessary. This work examines the effect of LSP at different input variability to induce its compressive stress. Various factors that affect the compressive stress of the LSP are tested with a serial experimental using 30CrMnSiNi2A as workpiece. It was found that the in-depth residual stress induced by LSP were a function of laser power density,laser beam spot size, laser pulse width and pulse repetition.

Abstract: In this paper, the Lattice Boltzmann Method is applied to set up the numerical model of cavitations. In order to simplify the model without losing the accuracy of simulation, the movement of the bubble wall is considered as the boundary condition for the gas and as initial condition for the fluid so the two phases (gas-fluid) physical phenomenon is divided into two simple models which are connected by the bubble wall. In the simulation, through the analysis of the velocity and the pressure distribution, it is found out that the symmetric bubble is characteristic with pulsation and high speed shock that are limited in a small field with radius of 7mm during the bubble growth. And it noted that the bubble is circularly collapsed for the symmetric velocity distribution.