Applied Mechanics and Materials Vols. 284-287

Abstract: The paper deals with the numerical analysis of forced vibrations of a slender water tower structure. The computation model has been developed using finite elements in the ANSYS program environment. For CFD (Computational Fluid Dynamics) analysis the CFX module was used. The computation model includes the precisely modeled thin-walled steel structure and two variants of fluid domain. Elements FLUID30 formulated for direct description of the fluid pressure field has been applied and Lagrange description FLUID80. The Raleigh’s model of energy dissipation has been used. Similarity of normal modes of vibration has been applied as the criterion for defining the relations between computed natural frequencies of the empty tank and filled with water. To obtain accurate wind induced forces the CFD model of air surrounding was modeled. From this model the relation between velocity of unaffected stream and vortex separation frequency. Forced vibrations of the tower excited by vortex shedding harmonic pulsations have been computed.

Abstract: Large anchorage system with anchor bolt exceeding 50mm of bolt diameter or effective embedment depth deeper than 635mm is usually used in nuclear concrete structure, but shear design criteria for large anchorage system is not clearly addressed by ACI 349-06 Appendix B (ACI 349, 2006). Therefore, to find out the shear characteristics of large anchorage system, 24 prototype specimens were manufactured and tested by ASTM E 488. Test variables are anchor bolt diameter( d_o= 63.5, 76.2, 88.9mm), effective embedment depth ( h_ef= 635, 762mm), and edge distance( c₁=381, 508, 762mm). Concrete compressive strength was constant.( f'_c= 38MPa) and anchor bolt(steel), high strength anchor bolts of ASTM A 540 class B were used. Test results as follows : Shear strengths calculated by ACI 349-06 and CCD method overestimate shear strength of large anchorage system exceeding 50mm of bolt diameter(d_o ). As the edge distance(c₁ ) increased, the shear breakout fracture force increases. Anchor bolt diameter(d_o ) and effective embedment depth(h_ef ) have little influence on shear strength of large anchorage system, but edge distance(c₁ ) is more related with shear strength of large anchorage system.

Abstract: The 2 × 4 construction system arose in North America and is supplied throughout the world; however, there has been no clear identification of its application under various conditions in different regions. This paper identifies localized 2 × 4 construction systems by comparing the changes in its practice in six countries and the countermeasures taken against earthquakes, which are a major influence on local environmental conditions. The foundation, floor, wall, and joints built using the 2 × 4 construction system of each region were compared and analyzed with regard to their countermeasures against earthquakes, and the results were summarized to propose a 2×4 construction system to counteract earthquakes.

Abstract: This paper extends the recently developed cross modal strain energy (CMSE) method for damage localization and severity estimation, using limited modal data, with iterative process. For investigating the performance and verifying the effectiveness of the present CMSE method, the numerical study of this article chooses a damaged beam that was investigated in a published article. The numerical result indicates that the CMSE method is capable of detecting the damage locations and estimating their severities properly, even when only few spatially incomplete, noisy modes are utilized.

Abstract: As the building sector accounts for about 30% of Taiwan’s carbon footprint, improving the Green Building Literacy (GBL) of building owners or users through general education is important to the carbon reduction commitment. This study aimed to use Delphi method and action research to innovate undergraduate curriculum of Green Building Introduction in general education to foster GBL. According to the suggestions by the Delphi panel and guidance of GBL model which was constructed from paper review and countrywide survey data by using structural equation modeling, the GBL curriculum not only conveys the knowledge of fact but more emphasizes on the knowledge for action and basic design skill through the involvement in the specific activities, which are also used to improve students’ attitudes and responsibility to promote their behavioral performance. The evaluation of the curriculum showed that there are significant improvements in the cognitive domain and the attitude-behavior domain of students’ GBL.

Abstract: Reactive powder concrete (RPC) has been proposed as barrier materials for the construction of engineered barrier in a low-level radioactive waste disposal site. The durability characteristics of RPC in such applications become paramount for the success of the containment of the wastes. The adverse environmental conditions at the disposal site could attack concrete barrier material and result in degradation of the material. Laboratory tests were conducted on RPC with various compositions to investigate the physical and durability properties of RPC. The effects of the addition of cement, silica fume, quartz powder, silica sand, steel fiber, and 2 levels of water-to-binder ratio (W/B = 0.25 and 0.30) on the properties of RPC specimens were investigated. Experimental results indicate that the long-term durability of RPC is significantly improved with the hydration of pozzolanic materials, which produces a very dense structure and thus exhibiting improved durability. The coefficient of permeability of RPC matrix determined using gas permeability apparatus demonstrated that RPC has much lower permeability than that of ordinary concrete. Heat-treating of concrete at 80°C accelerates the hydration process of RPC and shows enhanced physical and durable characteristics, as demonstrated by the chloride penetration test results.

Abstract: In conjunction with the promote of Industrial Building System (IBS) in Malaysia building construction, precast units such as slab, beam and column were widely used. This paper reports on the determination of the effective cross sectional area of the proposed cold-formed sections that embedded in precast concrete slab. The cold-formed steel sections are single and double lipped channel section, with 100mm in depth, 50 mm width, 12 mm lips length and 1.55 mm thickness. In order to determine the flexural capacity of the composite slab system, it is necessary to identify the effective cross sectional area of the section contributes to load-carrying of the slab system. The calculation method was based on the effective width method concept from BS EN 1993-1-3 and BS EN 1993-1-5. Four types of cold-formed steel frame profiles that embedded in the concrete to form a new type of composite slab system were used to study in this paper. The four types of cold-formed steel section configuration are S1-SV, S2-SH, S3-DV and S4-DH. From the analytical calculation, S3-DV has the highest effective cross-sectional area, which it only consists of 2% ineffective area for load-carry capacity. Besides that, single lipped section S2-SH fully utilized the cross sectional in carrying load. It can be concluded that S3-DV is predicted to have highest bending resistance than other three types of configuration with condition that the reliability of the prediction need to verify as other factors such as shear bonding and shifted neutral axis happened due to combination of concrete and cold-formed section which, will also contribute the strength capacity of the composite slab system.

Abstract: In seismic engineering, the dynamic property of the soil is one of the most important aspects in ground response analysis. Dynamic property is significantly affected by local soil deposits. Shear wave velocity (Vs) of soil is one of the main parameters in determining the amplification factor on ground surface. It is not economically feasible to measure Vs for all sites. Therefore, a reliable empirical correlation between Vs and standard penetration resistance (Nspt) will be useful since Nspt data are easily obtainable in construction industry. This study aims to develop an empirical correlation between Vs and Nspt for all soils by considering the effect of site classification according to the Uniform Building Code. New empirical correlations for all soils are presented in this study and well compared with the previous study to evaluate prediction capability. Results show that site classification has a significant impact on the Vs estimation, and that the proposed correlations are the most appropriate for estimating the Vs profile in the studied area compared with existing correlations.

Abstract: The reduction in energy usage is proven able to minimize the carbon dioxide emission. By promoting energy efficient practices at Rest and Service areas (RSAs) along the highway, it is able to decreasing the carbon dioxide emission. This paper highlights the outcome of a study aims to compare the energy consumption of the RSA that utilized HVAC (heating, ventilation, and air conditioning) and non-HVAC. Thus, the study extends to determine the potential retrofitting of RSAs that responsive to more energy reduction. Data collection conducted at the 6 RSAs in PLUS highway, Johor Region of Malaysia which are Pagoh RSA (Northbound & Southbound), Machap (Northbound & Southbound), and Gelang Patah (Northbound & Southbound). The results show that the energy consumption at Machap Northbound RSA is considered very high in comparison to the other RSAs in Johor Region that not utilized full HVAC. Thus, it was proven that the usage of full HVAC system contributing to the increase of energy consumption at the RSA. Simultaneously, the carbon emission is also directional proportion to the energy consumption at the RSAs. Some retrofitting is potential to be applied for more energy efficiency in order to support the maximum energy reduction at the RSAs. In example, reducing the number of air-condition unit at the café is significant to be taken to reduce energy wastage for all 6 RSAs. In conclusion, energy efficient RSAs can be achieved by applying good energy management, installing best energy saving appliance and implementing passive design strategy.

Abstract: Ultrasonic pulse method is a non-destructive testing method used for testing materials. For concrete, it is used mostly for determination of dynamic elasticity modulus, compressive strength, homogeneity, to determine depth of cracks or as a supportive method for testing frost resistance. Applicability of using ultrasonic pulse method for evaluation of degradation of concrete exposed to high temperature was proved. This method is unambiguously utilizable for rationalization of experimental work focused on optimization of composition of concrete resistant to high temperatures. Ultrasonic pulse method can be also used for mapping the degree of degradation of concrete elements and structures, which can be measured by means of direct sounding. Appropriateness of the use of ultrasonic pulse method for evaluation of degradation of concrete exposed to high temperature was proved. This method is unambiguously applicable for rationalization of experimental work focused on optimization of composition of concrete resistant to high temperatures. Ultrasonic pulse method can be also used for mapping degree of degradation of concrete elements and structures, which can be measured by means of direct sounding.