Applied Mechanics and Materials Vols. 99-100

Abstract: in this paper, super low noise mining system is analyzed with dynamics model, every constructional element is studied with analysis of kinematics and dynamics, the path of the mass center, angular velocity and angular acceleration of every constructional element is obtained. Nonlinear vibration differential equations of the system are obtained according to Alembert principle. Through numerical analysis, the enforced situation and dynamo load torque of the joint between every constructional element is gained, the influence of crank angle on system response is acquired, and the result has a certain reference value to optimization of the system.

Abstract: The mechanics properties of HPC mixing different dosage and length of polypropylene fiber were investigated in this study. The results showed that the addition of appropriate amount and length of polypropylene fibers in HPC led to an effective improvement in the tensile strength and a little change in the compressive strength of HPC. The pronounced improvement can be attributed to the beneficial effect of polypropylene fiber on HPC by restraining the generation and development of the micro cracks in concrete, enhancing the level of stress and deformation and damage characteristics in HPC, furthermore, extending the durability and safety of concrete structure.

Abstract: Excavation of the soil is actually the unloading process. The unloading process of soil makes the soil uplift, and the soil uplift is restricted by the pit engineering piles. And then, engineering piles should bear the vertical upwards pulling force caused by soil uplift. When pulling force is huge and tensile bearing capacity of pile is low, engineering piles could be pulled apart, and it is harmful to bearing capacity and durability of engineering piles. This paper adopts the finite element method to simulate engineering piles during pit excavation, and studies the traits of engineering piles in various excavation working conditions and different position. The computational results show that the deeper pit, the bigger displacement and tensile forces of piles, and the farther away from edges of the pit, the bigger displacement and forces of piles. In addition, the paper also gives a formula about the relationship between depth of pit excavation and uplift force on piles.

Abstract: In this study, by the way of adding functional carbon nanotubes into the SBS modified rubber powder to obtain a new type of composite asphalt modifier. The new modified bitumen was prepared with the asphalt compound modifier. A lot of structure and road performance tests were carried out about the new modified asphalt and its mixture. The results demonstrated that after adding new type of carbon nanotube, the modified asphalt obtained a more stable internal structure; the performance index (softening point, penetration, and ductility) had better performance.

Abstract: This paper presents the study on GFRP bar reinforced concrete bridge deck that is designed as typical one-way concrete slab. Parametric study of deck thickness, girder spacing, and environmental reduction factor was performed, on the basis of requirements per ACI 440.1R-06 guideline, from which the results show that design of GFRP RC deck is controlled by the cracking serviceability but not the ultimate flexural moment.

Abstract: This paper presents the investigation of sustained stress level in GFRP bar used as main reinforcement in typical reinforced concrete bridge deck, which is often subject to severe environmental exposures in North America. AASHTO LFRD approach is used for the design of GFRP RC deck that also meets with the requirements per as specified in ACI 440.1R-06. Research results show that the sustained stress level in GFRP bar varies in the range of approx. 3% -7% for bridge deck with various deck thickness and girder spacing.

Abstract: According to the strain energy equivalent, the resonant response equivalent static wind load of large span roof is derived. It solves the matter that should consider numerous structural response control objects on calculating equivalent static wind load for large span roofs, and establishes relationship with the structural strain energy introduced by fluctuant wind loads. Finally, the method is used to resonant equivalent static wind load analysis of 2008 Beijing Olympic Tennis Center Stadium roof structure. The results illustrate that the method proposed in this paper is effective and the precision is reliable.

Abstract: Abstract. How to evaluate the follow-up effect of the high-speed development of the Chinese real estate is a topic that has drawn the attention of people with lofty ideas in China or even throughout the world. This essay, taking the method of statistic analysis and synthetically study, put forward a proposition about the negative effect of the Chinese real estate and hold the view that China's real estate development implies a number of negative effects. These are mainly reflect in that the proportion of the real estate investment is too heavy which in turn takes investment away from other industries, the gap between the house price and the citizen's purchase ability is becoming wider and wider which increases the difficulty of the public housing consumption and the real estate foam has showed its appearance in some cities which buries deep risk to the national economic development. In addition, the local government’s over-reliance on taxes of transfer of land and real estate and weak implementation to the central macro-control policies, If this trend continues, it will inevitably lead to that the central government's order is not strictly enforced and the situation is difficult to control.So, it concludes that there's tremendous potential crisis in the Chinese real estate which needs us to treat it with high vigilance and to regulate and control it in a proper way.

Abstract: This paper presents the influence of ultra-fine fly ash on the strength development and durability characteristics of high performance road concrete. The durability of high performance road concrete is investigated including the permeation resistance under hydraulic pressure, the resistance to rapid freezing and thawing, the wear resistant ability and drying shrinkage. Results on compressive strength and strength development of high performance road concrete are also obtained with the main variables being the partial replacements of cement by ultra-fine fly ash of 20%, 30% and 40% by weight of binder material and the binder material of 360kg/m3 and 400 kg/m3. The test results indicate that the use of ultra-fine fly ash as cement replacement leads to a significant improvement of high performance road concrete resistance to permeation and rapid freezing and thawing. The later compressive strength of concrete containing ultra-fine fly ash is also found to be significantly higher than that of control concrete. The wear resistant ability of high performance road concrete is significantly higher than that of control concrete with similar workability. The high performance road concrete also shows the lower drying shrinkage.

Abstract: According to the time-varying analysis theory of large-span structure hoisting, the structure transformation matrix around three-dimensional translation and rotation is obtained. Based on the obtained transformation matrix, the final state matrix after structure hoisting can be described, and the structural internal force of any position can be calculated. Using the Coin3d Open Inventor that is an open source graphics development kit, developers exploited simulation software of large-span structure hoisting. The software can analyze structural security with the time-varying analysis theory, and it has been applied in the simulation of hoisting construction at the Hefei Xinqiao international airport. The results indicated the software is reliable to protect safety of structure hoisting.