Applied Mechanics and Materials Vols. 71-78

Abstract: There are six basic control items, land saving, energy saving, water saving, material saving, indoor environment and operation, among which, only material saving are related to structure design. We followed the green building design concept and the control items list in those standards during structure design of one of the residential area in Sino-Singapore Tianjin Eco-city, which consist of 15~18-story residential building connected to a large underground garage, as is shown below.

Abstract: For a healthy environment for hot spring recreation, this study discussed the diffusion in the bathroom of hydrogen sulfide gas from hot sulfur springs for an improvement of this harmful situation. Based on empirical measurements and then comparing the results with CFD simulation, the analysis exposed the distribution status of indoor hydrogen sulfide and its diffusion behavior. Results indicate that sulfur springs produce high levels of hydrogen sulfide that are hazardous. And the high concentrations can be improved under ideal ventilation, which was determined by the air exchange rate, flow field efficiency, turbulence and vortex phenomena.

Abstract: In this paper, the system and the design philosophy of wheel-spoke cable-membrane structure of Baoan Stadium is introduced firstly. And then the study of wind tunnel test on 1:250 scale model is mainly presented, together with the numerical calculation of the wind dynamic response. Finally, the wind-resistant design of the roof structure based on the results of wind tunnel test and the foreign design codes is generally introduced.

Abstract: One-dimensional confined compression tests have been used to investigate the compressibility of granulated rubber-loess mixtures with rubber content of 0,10,20,30,40,50,100%. The purpose is to find the compression probability of their usage as a lightweight fill material. The results indicate that the compression properties of mixtures are between pure compact loess and pure granulated rubber. The coefficient compressibility, elastic strain, and recover strain increase with increasing rubber content. Granulated rubber-loess mixtures showing behavior of modular variation with changing granulated rubber content, can be used as lightweight materials in civil engineering applications to sharply reduce the tire disposal problem and solve problems concerned with stress and deformation.

Abstract: This paper uses centrifugal spray drying process to prepare powder polycarboxylate superplasticizer. The best spray drying process: speed of centrifugal atomizer is 16000r/min, feed liquid temperature is 30°C, import / export air temperature of drying chamber is 200°C/80°C. It achieves a high concentration of polycarboxylate superplasticizer to prepare powder product. It solves the problem of sticky and low-performance of powder polycarboxylate superplasticizer during traditional preparation. Analyzing the structure of polycarboxylate superplasticizer before and after spray-drying by infrared spectroscopy, and verifying the conclusion through macroeconomic performance experiments.

Abstract: C40R60 High volume fly ash (HVFA) concrete were adopted for the continuously casting massive foundation slab of Tianjin Tower, which has a volume of about 20 000 m³, to decrease the risk of cracking during the construction process. Suitable raw materials and mix proportion were chosen. The properties of hardened concrete cured under different conditions were investigated. A mock-up of massive structure with the dimension of 4.5×4.5×4m was cast using determined concrete. The temperature development in the core of structure was measured. The results show that the temperature rise in the core is relatively low and the compressive strength curing under the standard condition for 60 days is 54.3MPa. HVFA concrete is much suitable to the massive concrete structure in which elevated temperature would be kept for a long time.

Abstract: The objectives of this work are to study the influence of fluoride additives on aluminum recycling from the boiler slag. The effect of adding different amounts of fluoride, such as NaF, NH₄F, KF and CaF₂, was investigated. An elemental analysis of aqueous solutions leached by sulfuric acid and hydrochloric acid was determined by EDTA-Na₂-ZnCl₂ titration method. The components and microstructures of the samples were examined by means of XRF, XRD and SEM. Acid strength, leaching time, solid/liquid ratios and different additives were conducted in this experiment. The fluoride additives have a significant effect on the leachability of alumina in the boiler slag. NH₄F is the best choice economically because of low dosage and high efficiency.

Abstract: The article studies the method which hydroturbine part is manufactured by lost foam casting for obtaining higher quality product.The lost model material is polystyrene foam plastics,the EPS diameters are selected in 0.5-0.76mm,the casting raw material is lower carbon martensite stainless steel(ZG06Cr13Ni4Mo).The style of open pouring system is adopted, ∑F_in-gate：∑F_cross-gate：∑F_down-sprue=1：1.1：1.2, fireproof coating is mixed and coated,square sand box is used. The pouring temperature of liquid is 1600-1650°C.If the technology is strictly according to the design,good quality casting can be gotten.

Abstract: The high-pressure crystallized poly (ether ether ketone) (PEEK) samples were investigated using thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The results showed that the thermal stability of PEEK could be improved through appropriate high-pressure treatment. Although the 10wt.-% loss temperature and maximum decomposition temperature of the PEEK samples decreased with the increase of crystallization temperature and crystallization time, the effect of the applied pressure on preventing them from further degradation was obviously observed. Furthermore, the amorphous region of certain PEEK samples was eroded off after high-temperature degradation, which made the details of the spherulitic structures revealed more clearly using traditional etching technique. PEEK spherulites with different characteristics were disclosed with SEM, including those with sheaf-like structures, quench haloes or interpenetrating fibrils. The study presented here may be instructive to the applications of the polymer under such ultimate environmental conditions as high pressure and high temperature.

Abstract: Artificial boundary is an important part of finite element calculation model. Based on finite element method, this paper presents substructure condensation elements to simulate far field boundary. As most dynamic responses are focused on ground surface, substructure elements’ internal nodes are condensed and only keep the nodes on the ground surface to maintain the accuracy of scattering wave transmition. According to the example of verification, if the related parameters are chosen properly, the effect of substructure condensation boundary is guaranteed.