Applied Mechanics and Materials Vols. 479-480

Abstract: Tatun volcano group is located in north Taiwan and near Taipei Basin where several million people live there. Although it provides hot spring and landscape for citizens and keeps calm most of time, the threat remains, particularly for the two nearby nuclear power plants. This paper discusses the seismic hazard of volcanic seismic source including source characterization of Tatun volcano group, probabilistic seismic hazard analysis (PSHA), and its preliminary seismic hazard result. Based on nuclear regulatory requirement for PSHA, the uncertainties of source parameters are vital, such as geometry, maximum earthquake, and activity relating earthquake catalog selection, so the first-time seismic source characterization workshop for volcano is held to let domestic experts discuss their hypotheses and investigation result. Hence, the renewed source parameters can represent current geo-science for Tatun volcanic seismic source, and the process of PSHA can lead the better way to combine the result of different research projects for Tatun volcano.

Abstract: Under the conditions that the exact component causing system failure may be unknown or masked, we present an iterative approach to estimate the component lifetime parameters of a system consisting of two Weibull components. The time and cause of system failure are assumed to follow a competing risks model, and the masking probability of minimum random subsets are not subjected to the symmetry assumption. On the basis of considering the effect of failure time and component, we redefine the computation of masking probability and the likelihood function is derived for the masked data. An iterative procedure for finding the maximum likelihood estimates is presented via an EM algorithm. The developed approach is illustrated with a simple numerical example.

Abstract: In the building industry, decreasing the CO₂ emission not only is an important environmental issue but also an international responsibility in the future. This research analyzed building life cycle CO₂ emission and used a building life cycle CO₂ emission index (LCCO₂). LCCO₂ allows us to compare the impacts of different building designs to the environment and finds out the most efficient CO₂ reduction strategy. A low floor house life cycle simulation showed that most CO₂ emission in the life cycle comes from the daily use stage. Therefore, energy preservation in the daily life is the most important strategy to reduce CO₂ emission in a building. Compared with the RC house, the light weight steel house uses more eco-friendly building materials and heat preservation materials. Therefore, the LCCO₂ of the light weight steel house is reduced 31.34%. The research also showed that proper increase in the life span of the building also decreases CO₂ emission. The light weight steel house is more eco-friendly than the RC house in the buildings life cycle.

Abstract: To get the precise input motion for seismic analysis of important structures located in liquefiable soil layers, this study demonstrates site response analysis using FLAC 3D [. Based on the previous earthquake diaster experiences and regulatory requirements for nuclear power plants (NPP), the seismic wave propagation in the site having dipping bedrock surface was modeled, also the excess pore water pressure during excitation process was added into the soil elements. The free-field site response model is used to generate the response spectra at different ground surface locations, and to predict the influence range of soil liquefaction. The analysis results show that soil liquefaction could reduce site amplification effect, and might have different degree of impact depending on natural frequency and soil pressure resistance of structures. The 3D model also can capture the soil unceratinties and reflect the real topographic effect in one computer run, so the current multiple one-dimensional equivalent linear analysis process could be improved. Therefore, the FLAC 3D model can fulfill nuclear regulatory requirement, and provide suitable ground-motion prediction for liquefiable soil sites and complex bedrock surface sites for the need of seismic evaluations of existing NPPs after Fukushima Dai-ichi Tragedy.

Abstract: This paper presents a prototype C-based multi-agent system, called Sensor Agent Cloud (SAC), for multi-level based environmental and physiological signal monitoring and analysis. The SAC has a four-layered system architecture including the user interface layer, regulation layer, sensor agent group layer and sensor node layer. Two ultra-compact PC-based sensor nodes are prototyped by individually integrating a fully functional ultra-compact computer with two kinds of embedded systems. Proof-of-concept examples on sensor node data retrieval are used to illustrate and validate the low-level operations for SAC administrators through C/C++ mobile agents as well as the high-level operations for SAC end-users through Google Cloud services.

Abstract: The pond irrigation system, which was developed in the early twentieth century, is an effective rainfall harvesting method that exploits geographical features to overcome hydrologic disadvantages. The concept of the pond irrigation system is to reserve excess rainwater runoff in farm ponds that act as small reservoirs supplying water to farmlands during the drought periods. This study aimed to promote the pond irrigation systems in the Tao-Yuan area. The irrigation system model developed in this study shows how agriculture water demand in a region can be fulfilled by adjusting system dynamics of waterways such as canals, river weirs, and farm ponds. This water demands can be met in 2 ways: (1) deep-ponding irrigation and (2) adjusting the backup storage ratio of farm ponds between up- and down-stream areas. Our analytical results showed that deep-ponding irrigation could be used to effectively harvest rainfall to reduce agricultural water demands from the Shih-Men Reservoir and increase the amount of water reserved for farming purposes. Furthermore, in our model, during drought periods and/or when the reservoir water supply is inadequate, the backup water storage ratio in the downstream regions is greater than that in the upstream regions, such that water in upper ponds is reduced and the storage capacity of lower ponds is increased to store more return flow from upstream.

Abstract: In Taiwan, many industrial facilities are located in coastal regions. A large portion of those facilities are constructed with stainless steel. Over time, sodium chloride from seawater vapor would deposit on the surface of the facilities and the chloride ions in it can lead to corrosion and cracks. This process is the so-called stress corrosion cracking (SCC). Theoretically, the SCC failures increase with the level of residual stress created by the welding and cold working processes. Practically, however, the corrosion risk is governed by various intrinsic and extrinsic factors that interact as a complex process. In this paper, we propose a dynamic approach for controlling the SCC risk. Firstly, we review some recent experimental work and filed investigations on stainless steel facilities in Taiwan. Following that, a dynamic risk management approach is explained and applied to develop a research roadmap for controlling the complex corrosion risk. In sum, we find that the best way to control the corrosion risk of the facilities is to remove the chlorides from the air by an ion exchange process accompanied with continuous monitoring and maintenance efforts during their operation life cycle.

Abstract: This paper reviews the recent experimental work on steel welds and connections, as to investigate the effects of corrosion on steel welded frames in the urban areas in Taiwan. In the first part of the paper, the tensile strengths have been compared for steel welds with and without rust. In the worst case, the steel plates were placed outdoors for 9 months, as to cause pitting on the welding surface (i.e. the rust level was raised to the SSPC level D). The rust was found to reduce the strength 5% on average. In the second part, the hysteresis loops were depicted and compared for the 2 connections taken from an existing building. The connections were tested after being exposed to air and moisture 10 years. The non-rehabilitated connection developed strength well until the top beam flange fractured at the interstory drift over 3%. Despite that, the connection tests didnt show any impacts of corrosion. Based on the above work, corrosion can be considered to affect the steel welded frames in Taiwan, but to a limited extent.

Abstract: It’s very common in Taiwan to use ceramic tiles as an external wall material. Even the nature of ceramic tile is stable, the deterioration such as chaps and peeling still occur on external walls, which should face the tough conditions like sunshine, raining, etc. In this study, the conditions of deterioration of ceramic tiles on exterior walls were clarified by the field investigation of townhouse, built during 1971~1990, in Kaohsiung City.After analyzing and comparing the deterioration of the above cases, the conditions of deterioration of external wall tiles, used on townhouses, were found as follows:The main deterioration of Mosaic tiles is rust stains, cracking and flaking.The main deterioration of square tiles is rust stains, efflorescence and cracking.The main deterioration of rectangular tiles is rust stains, cracking and flaking.

Abstract: The aim of this paper is to study the interaction between adjacent structures with different foundation levels under earthquake loading conditions. Structures and soil are represented by two different models. In the first case, the structure itself is modeled with standard frame element, whereas the soil behavior is stimulated by a special grid model. In the second case, the structure and soil are represented by plane stress or plane strain elements. The Interaction between the two structures is demonstrated and discussed via numerical examples using the proposed method and program. In case of the structures having shallow foundations, the interaction is small and negligible. If the foundation of one structure is shallow and the other one deep, then the interaction renders the forces in one structure 20% smaller than those in a single shallow structure, If the neighboring structures have the same deep foundation level, then due to interaction the forces in one structure are 25% larger than those in a single deep structure.