Master of Engineering (Research) / This report investigates the down-aisle buckling load capacity of steel storage rack uprights. The effects of discrete torsional restraints provided by the frame bracing in the cross-aisle direction is considered in this report. Since current theoretical methods used to predict the buckling capacity of rack uprights appear to be over-conservative and complex, this research may provide engineers an alternative method of design using detailed finite element analysis. In this study, the results from experimental testing of upright frames with K-bracing are compared to finite element predictions of displacements and maximum axial loads. The finite element analysis is then used to determine the buckling loads on braced and un-braced uprights of various lengths. The upright capacities can then be compared with standard design methods which generally do not accurately take into account the torsional resistance that the cross-aisle frame bracing provides to the upright. The information contained in this report would be beneficial to engineers or manufacturers who are involved in the design of rack uprights or other discretely braced complex light gauge steel members subject to axial loads.

The paper aims to investigate the effects of ¡§Local Government Act¡¨on the ¡§centralized personnel system¡¨ of the government employee ethics unit. Before the promulgation and implementation of the Local Government Act, the laws of local self-government for the local government agencies to follow and observe were ¡§The Taiwan Local Self-Government Guidelines¡¨, ¡§The Self-Government Law for Provinces and Counties¡¨, and ¡§The Municipal Self-Government Law¡¨. In fact, the local self-government implemented by the county and municipal governments only existed in name because the so-called local self-government was still under the control of the Central Government. Before the government employee ethics unit was reorganized in 1992, the government employee ethics officers were put in the government departments of different levels as well as the state-run enterprises in Taiwan, and subordinated to the personnel units of these institutions. They were responsible for maintaining the safety and security of the institutions, investigating the loyalty of the staff members, and so on. After the implementation of Local Government Act, the chiefs of local government agencies elected by the people have been vested much more personnel authorities. They also expect a higher level of autonomy as the self-consciousness of the people is growing high. Along with this reorganization, the government employee ethics officers have turned into the staff members to assist the chiefs of local government agencies. Meanwhile, based on their statutory job duties, these staff members concurrently assume the great responsibilities for well-formed civil service ethics and anti-corruption practices for local government agencies.

No description available.

The use of cold-formed steel as a framework for floor systems in multi-story buildings and single occupancy residences is becoming an increasingly popular alternative to traditional materials and techniques. Builders and designers have recognized that the high strength-to-weight ratio provided by the cross-section of cold-formed steel members permits lighter structures and longer spans. The longer spans and lighter structures associated with cold-formed steel floor systems can result in vibration serviceability issues if proper design considerations are not made. Providing sufficient damping within the structure is the most effective way to ensure that occupants are comfortable under typical residential and office service loads. The modern, open-concept interior has open floor plans with few partitions and long spans, which result in inherently low structural damping. Cold-formed steel floor systems also have less mass than traditional floor systems, which will increase the amplitude of acceleration response. The vibration problems that may be present in cold-formed steel floor systems, like any other floor system, can be addressed if proper consideration is given by designers. Traditional design approaches for vibration serviceability have proven inadequate, and there are no current methods available to designers for calculating the response of cold-formed steel floor systems. In order to design a floor system to properly address occupant comfort, consideration must be given for the type of dynamic loading, resonance, dynamic response, and stiffness of the floor system. The objective of this thesis is to improve the understanding of the dynamic characteristics of cold-formed steel floor systems, and recommend an adequate model for predicting the dynamic response and modal properties of floor systems, in order to aid the design process. This thesis presents the results of an extensive laboratory and field study on the vibration of cold-formed steel floor systems. Floor systems built with cold-formed steel TreadyReady® joists and subfloor assemblies containing OSB, FORTACRETE®, sound reduction board, cold-formed steel deck, and LEVELROCK® topping were examined. Previous research has presented the observed influence of construction details on the modal properties of the laboratory floor systems tested. This thesis discusses the influence of different details on the transverse stiffness of the floor systems. It was found that effectively restrained strongbacks, and cold-formed steel deck subfloor assemblies provided significant increases in transverse stiffness. Based on the analysis of the field testing data, recommended design damping ratios are provided for floor systems constructed with the materials investigated in this study. Floor response that can be compared to serviceability criteria is presented. The peak RMS acceleration from walking excitation was found to be within the acceptable range for the ISO criterion based on residential occupancy, and the static deflection from a 1 kN point load was found to be within the acceptable range of Onysko’s criterion. An adequate design criterion for vibration requires a limiting value, and a means of estimating floor response for comparison. The AISC, ATC, and Smith, Chui, and Hu Orthotropic Plate design methods were evaluated by comparing predicted frequency against measured frequency for the test floors. The ATC and Smith, Chui, and Hu Orthotropic Plate methods were evaluated by comparing predicted deflection against measured deflection for the test floors. The ATC method is recommended as the best method for calculating floor response based on current publications. A design procedure is recommended for cold-formed steel floor systems, using the ATC design guide. The ATC acceleration criterion for walking excitation must be met for floors with fundamental frequencies of less than 15 Hz, and the ATC static deflection criterion must be met for all floors. Proposed modifications to the ATC method to improve the design of cold-formed steel floors include: adopting the recommended design damping ratios from this thesis; adopting the frequency-weighted ISO limiting acceleration and, obtaining several coefficients and empirical expressions that are relevant to cold-formed steel floors from further testing. Recommendations for improving the floor testing procedures at the University of Waterloo are given.

The use of cold-formed steel as a framework for floor systems in multi-story buildings and single occupancy residences is becoming an increasingly popular alternative to traditional materials and techniques. Builders and designers have recognized that the high strength-to-weight ratio provided by the cross-section of cold-formed steel members permits lighter structures and longer spans. The longer spans and lighter structures associated with cold-formed steel floor systems can result in vibration serviceability issues if proper design considerations are not made. Providing sufficient damping within the structure is the most effective way to ensure that occupants are comfortable under typical residential and office service loads. The modern, open-concept interior has open floor plans with few partitions and long spans, which result in inherently low structural damping. Cold-formed steel floor systems also have less mass than traditional floor systems, which will increase the amplitude of acceleration response. The vibration problems that may be present in cold-formed steel floor systems, like any other floor system, can be addressed if proper consideration is given by designers. Traditional design approaches for vibration serviceability have proven inadequate, and there are no current methods available to designers for calculating the response of cold-formed steel floor systems. In order to design a floor system to properly address occupant comfort, consideration must be given for the type of dynamic loading, resonance, dynamic response, and stiffness of the floor system. The objective of this thesis is to improve the understanding of the dynamic characteristics of cold-formed steel floor systems, and recommend an adequate model for predicting the dynamic response and modal properties of floor systems, in order to aid the design process. This thesis presents the results of an extensive laboratory and field study on the vibration of cold-formed steel floor systems. Floor systems built with cold-formed steel TreadyReady® joists and subfloor assemblies containing OSB, FORTACRETE®, sound reduction board, cold-formed steel deck, and LEVELROCK® topping were examined. Previous research has presented the observed influence of construction details on the modal properties of the laboratory floor systems tested. This thesis discusses the influence of different details on the transverse stiffness of the floor systems. It was found that effectively restrained strongbacks, and cold-formed steel deck subfloor assemblies provided significant increases in transverse stiffness. Based on the analysis of the field testing data, recommended design damping ratios are provided for floor systems constructed with the materials investigated in this study. Floor response that can be compared to serviceability criteria is presented. The peak RMS acceleration from walking excitation was found to be within the acceptable range for the ISO criterion based on residential occupancy, and the static deflection from a 1 kN point load was found to be within the acceptable range of Onysko’s criterion. An adequate design criterion for vibration requires a limiting value, and a means of estimating floor response for comparison. The AISC, ATC, and Smith, Chui, and Hu Orthotropic Plate design methods were evaluated by comparing predicted frequency against measured frequency for the test floors. The ATC and Smith, Chui, and Hu Orthotropic Plate methods were evaluated by comparing predicted deflection against measured deflection for the test floors. The ATC method is recommended as the best method for calculating floor response based on current publications. A design procedure is recommended for cold-formed steel floor systems, using the ATC design guide. The ATC acceleration criterion for walking excitation must be met for floors with fundamental frequencies of less than 15 Hz, and the ATC static deflection criterion must be met for all floors. Proposed modifications to the ATC method to improve the design of cold-formed steel floors include: adopting the recommended design damping ratios from this thesis; adopting the frequency-weighted ISO limiting acceleration and, obtaining several coefficients and empirical expressions that are relevant to cold-formed steel floors from further testing. Recommendations for improving the floor testing procedures at the University of Waterloo are given.

This research investigates prefabricated light-gauge steel and concrete panels using reliable and commercially viable shear connectors. An analytical and experimental investigation was undertaken to study the flexural behaviour of light-gauge steel and concrete composite panels under uniform pressure. Normalweight and lightweight concrete panels were fabricated by embedding 16-gauge 41 mm x 203 mm steel channel sections (running parallel to each other) to a depth of 38 mm into a 64 mm thick concrete slab. Push-out tests were also conducted to evaluate the efficiency of three types of shear connection mechanism; natural surface bonding, predrilled holes, and punched holes. Only two types of shear connectors (predrilled holes and punched holes) were used in the full-scale panel specimens. Results show that the predrilled holes and punched holes provide full shear transfer between the steel and concrete. The ultimate load carrying capacity of the lightweight concrete panels exhibited similar behaviour to the normalweight concrete panels. All the panels exhibited good load carrying capacity and ductility, and satisfied the serviceability limit state of deflection. Thus, the proposed panels present a potential for a commercially viable composite floor system for building construction utilizing a maximum span of 2330 mm.

Aim: The prevalence of dental erosion is still increasing. A possible preventive approach might be rinsing with edible oils to improve the protective properties of the pellicle layer. This was tested in the present in situ study using safflower oil. Methods: Pellicle formation was carried out in situ on bovine enamel slabs fixed buccally to individual upper jaw splints (6 subjects). After 1 min of pellicle formation subjects rinsed with safflower oil for 10 min, subsequently the samples were exposed in the oral cavity for another 19 min. Enamel slabs without oral exposure and slabs exposed to the oral cavity for 30 min without any rinse served as controls. After pellicle formation in situ, slabs were incubated in HCl (pH 2; 2.3; 3) for 120 s, and kinetics of calcium and phosphate release were measured photometrically (arsenazo III, malachite green). Furthermore, the ultrastructure of the pellicles was evaluated by transmission electron microscopy (TEM). Results: Pellicle alone reduced erosive calcium and phosphate release significantly at all pH values. Pellicle modification by safflower oil resulted in an enhanced calcium loss at all pH values and caused an enhanced phosphate loss at pH 2.3. TEM indicated scattered accumulation of lipid micelles and irregular vesicle-like structures attached to the oil-treated pellicle layer. Acid etching affected the ultrastructure of the pellicle irrespective of oil rinsing. Conclusion: The protective properties of the pellicle layer against extensive erosive attacks are limited and mainly determined by pH. The protective effects are modified and reduced by rinses with safflower oil. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Master of Engineering (Research) / This report investigates the down-aisle buckling load capacity of steel storage rack uprights. The effects of discrete torsional restraints provided by the frame bracing in the cross-aisle direction is considered in this report. Since current theoretical methods used to predict the buckling capacity of rack uprights appear to be over-conservative and complex, this research may provide engineers an alternative method of design using detailed finite element analysis. In this study, the results from experimental testing of upright frames with K-bracing are compared to finite element predictions of displacements and maximum axial loads. The finite element analysis is then used to determine the buckling loads on braced and un-braced uprights of various lengths. The upright capacities can then be compared with standard design methods which generally do not accurately take into account the torsional resistance that the cross-aisle frame bracing provides to the upright. The information contained in this report would be beneficial to engineers or manufacturers who are involved in the design of rack uprights or other discretely braced complex light gauge steel members subject to axial loads.

Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2007. / Härtill 5 uppsatser.

Aborda-se os principais aspectos da fundamentação teórica relativos ao dimensionamento de elementos em aço, constituídos por perfis de chapa dobrada, baseados nas prescrições das normas Americana e Canadense. A fundamentação teórica destina-se a justificar os procedimentos referentes ao dimensionamento de perfis de aço conformados a frio, em particular os elementos comprimidos e fletidos, além dos aspectos da flambagem local destes perfis. Aborda-se também uma análise dos métodos de projeto das estruturas metálicas formadas por estes perfis, apresentando-se algumas disposições e alguns aspectos interessantes e essenciais no desenvolvimento de um edifício industrial leve. Tendo em vista a grande utilização dos perfis conformados a frios em terças, desenvolveu-se uma sistemática de cálculo fornecendo os valores dos momentos admissíveis que poderão ser aplicados para um pré-dimensionamento. / An analysis of the theoretical basis for the design of cold-formed steel structural members, according to the American and Canadian Standards, is made. The theoretical background is used to justify the procedure to obtain the required geometry of the cold-formed steel structural members particularly the compression and flexural members, also to explain some aspects of the local buckling. Furthermore, an analysis of the design method of steel structures with these profiles is made. Some interesting and essential aspects are presented in what concerns to the development of a light industrial building. Having in mind the intensive use of cold-formed members in purlin structures, a procedure for systematic calculation was developed to determine the allowable bending moment values that can be used on a preliminary design.