Applied Mechanics and Materials Vols. 548-549

Abstract: In this paper, we exploded the technology of Sanhetu based on the historical records and previous studies. Mixing technology, molding pressure, W/S, curing time and curing method were investigated to increase the compressive strength of the imitating samples. XRD, FTIR and SEM were used to analyze the composition and consolidation mechanism. The results show that the compressive strength of the imitation could exceed 50 MPa, when molding pressure is 20 MPa, W/S is 0.49 with mixing technology A. Pozzolanic reaction is significant in strength development. And the reaction product, CSH gel, is the main factor in strength gain. Sufficient inner water of the imitating samples could contribute to the pozzolanic reaction. And increasing temperature could accelerate the reaction. The study confirms the possibility of the imitation for Sanhetu.

Abstract: Vertical greening as an important form of urban green space, it is an effective way to improve the city green coverage rate. This paper discusses the technology and the future trend of urban space stereo virescence, and in Beijing area as example this paper discusses the feasibility and expansibility, in order to help enterprise itself and the development of the industry.

Abstract: Purposes: this paper is to analyze and quantify the eco-effect of building green facade, providing a reliable application methods and theory basis for solving current environmental issues. Methods: this paper using facade renovation project of Wismar University in Germany as the carrier, it uses Energy-Plus energy simulation software, CFD computational fluid dynamics software and U-wert.net calculation software for U value of material to get the simulation analysis of the energy, physical and regional eco-effect of building green facade. Results: building green facade can increase 23.7% heat resistance value, save 6.2% of the year-round air conditioning load, reduce indoor temperature by 3-5°C in summer, reduce the air velocity by 0.03m/s, maintain the stability of indoor temperature, the annual indoor temperature can maintain 20.84°C, improve the indoor comfort. The temperature around the building can reduce by 0.5-4°C after green facade renovation, reduce the wind speed in the region by 0.05m/s, and reduce the annual carbon emission by 7.1%. Conclusions: Through the simulation results, eco-effect of building green facade play a significant role in cooling and insulation, energy saving, heat island mitigation, improving comfort, maintaining the balance of carbon and oxygen. It has become one important way to suture rift between man and nature in cities, being an effective way to solve today's ecological issues.

Abstract: This paper introduces the principle and characteristics of roof radiant cooling and displacement ventilation system, using numerical simulation method, the indoor airflow velocity and temperature field of the typical bedroom which uses the composite system in Ji'nan City under the different supply air velocity was calculated. The experimental results show that when the air temperature is 295.15K, to keep the indoor vertical temperature less than 3 °C, air speed should be greater than 0.1m/s and less than or equal to 0.3m/s, to provide reference for the application of roof radiant cooling and displacement ventilation system.

Abstract: The use of concrete aggregate from earthquake damaged building to make blocks which needed for post-disaster reconstruction has brought the social, environmental, economic and other benefits, at the same time respond to the basic state policy of low carbon energy saving. At home and abroad currently focused on the materials properties of recycled aggregate and recycled concrete block basic physical mechanics to study, but research for the material block wall structure performance is less, the research for the wall shear strength and anti-seismic performance of this kind of wall is of great significance. Based on the recycled concrete aggregate from Mianyang, Sichuan where is disaster area to make three hole hollow block wall (no reinforcement) to perform low cycle experiment, collecting four samples, and achieved anti-seismic indicators such as the hysteresis curves, skeleton curves of recycled concrete block wall, analyzes the influence of the axial pressure, the loading method on seismic performance of block wall.

Abstract: The discrete element method was used to simulate geogrid-reinforced ballast by pull out tests. Ballast particle was made of irregular clumps where its size and shape were considered by bonded spheres. The response of the ballast reinforced with geogrid under loading agrees with pull out experimental results. The micro-interaction between ballast particle and geogrid analyzed by microscopic parameters, contact force chain, force-displacement of the pull out tests was presented. It was also proved that the shape of granular particles, geogrid size and friction played an important role in ballast-geogrid system.

Abstract: In order to achieve the quantitative health diagnosis of operational tunnel, established the health diagnosis system and the evaluating criterion based on the mechanism of tunnel disease, used the weighted average operator to obtain comprehensive evaluation results, applied the asymmetric proximity to decide the grade of tunnel structure health, thus build a complete fuzzy comprehensive evaluation model. Finally, by taking the example of Lilong tunnel located at LiuHe Express way, and made analysis and evaluation to its structure health status. The results show that the improved grey relevancy method to determine the index weight can avoid the subjective arbitrariness and improve the reliability of the evaluation model, making a decision and analysis by asymmetric proximity insures the diagnosis results more correspond with the objective reality.

Abstract: The current proposed method has been developed using particle swarm optimization (PSO) technique. A single transverse open edge crack on a beam structure has been modeled using local flexibility matrix to determine natural frequencies. The PSO is a population based; bio-inspired evolutionary optimization algorithm that has been implemented for detection of crack. The frequencies obtained from analytical method have been used to train the PSO to get the desired output such as; relative crack depth and relative crack location. Mathematical modeling of the cracked beam structure is being done to ensure the integrity of the above algorithms. The results from the PSO show that both the size and location of the crack can be predicted efficiently through the proposed PSO.

Abstract: Modeling concrete compressive strength is useful to ensure quality of civil engineering. This paper aims to compare several Extreme learning machines (ELMs) based modeling approaches for predicting the concrete compressive strength. Normal ELM algorithm, Partial least square-based extreme learning machines (PLS-ELMs) algorithm and Kernel ELM (KELM) algorithm are used and evaluated. Results indicate that the normal ELMs algorithm has the highest modeling speed, and the KELM has the best prediction accuracy. Every method is validated for modeling concrete compressive strength. The appropriate modeling approach should be selected according different purposes.

Abstract: The dining room door with going out and coming in of people and goods is often opened, heating and air-conditioning building in order to energy-saving and preventing the outdoor air on indoor environment influence, install a set of air curtain at the entrance of the dining room door to stopping the outdoor air, commonly used air curtain is ceiling type air curtain. This article in view of the gate of one area, a layer of the dining room of Hebei University of science and technology of a new campus area set up physical model of air curtain and reasonable simplification, determining the calculation area of the numerical simulation and air curtain close condition. Then adopting the UFD method to wind pressure, hot pressure and the air curtain air flowing of the local hot pressure stack of main entrance set up physical model, through the numerical simulation of air curtain different jet angle, demonstrate the air energy-saving effect, provide the reference for the choice of the air curtain.