Dynamic Analysis on RCC and Composite Structure for Uniform and Optimized Section

This study examines the composite structure that is increasing commonly in developing countries. For medium-rise to high-rise building construction, RCC structures is no longer economical due to heavy dead weight, limited span, low natural frequency and hazardous formwork. The majority of commercial buildings are designed and constructed with reinforced concrete, which largely depends on the existence of the constituent materials as well as the quality of the necessary construction skills, and including the usefulness of design standards. Conventional RCC structure is not preferred nowadays for high rise structure. However, composite construction, is a recent development in the construction industry. Concrete-steel composite structures are now very popular due to some outstanding advantages over conventional concrete and steel structures. In the present work, RCC and steel-concrete composite structure are being considered for a Dynamic analysis of a G+25-storey commercial building of uniform and optimized section, located at in seismic zone IV. Response Spectrum analysis method is used to analyze RCC and composite structure, CSI ETABS v19 software is used and various results are compared such as time period, maximum storey displacement, maximum storey stiffness. Maximum storey shear and maximum stoey overturning moment. Keywords: RCC Structure, Composite Structure, Uniform Section, Optimized Section, Shear Connector, Time Period, Storey Displacement, Storey Shear, Storey Stiffness, Response Spectrum method, ETABS

A Heuristic Approach to Dynamic Stiffness Control

For appropriate and even superior performance yet cost reduction, this work was performed with the aim of weight reduction in the overall design and construction of possibly any machine tools. As far as our literature search is concerned, there does not seem to be much work published regarding successful weight reduction while maintaining performance using mass participation factor (MPF) in the areas of interest of the machine tools. In order to accomplish this task, we started with the ‘bed’ compartment of a CNC system and resorted to using the finite element analysis (FEA) software package and thoughtfully manipulated the available data/parameters until the desired results were obtained. The most important parameters were static stiffness, dynamic stiffness, and damping ratio. On the ‘bed’ of the machines’ compartment currently in production, it was so identified that there was unnecessary material (dead weight), and thus the FEA software was used in order to remove the unnecessary material by iteration. Finally, a new machine was built devoid of the unnecessary material, resulted in 9.3% weight reduction as predicted by the simulation, without sacrificing any accuracy and/or precision in performance.

A Design Procedure for Anchors of Floating Ocean Current Turbines on Weak Rock

In recent years, ocean current turbines have proven to be a reliable device for renewable energy generation. A crucial element of these turbines are the foundations, since they limit the displacement of the turbine, which is key in achieving efficiency in energy conversion, and can account for up to 26% of the total cost of the project. Most design procedures for foundations focus on sandy and clayey soils, but rock soils often predominate in tropical locations where marine currents are suitable for the installation of this type of turbine. This paper presents a design procedure for steel pile anchors (PAs) and concrete dead weight anchors (DWAs) on weak rock soils, using the assumptions of current technical documents and design codes commonly used in the industry for marine structures. Using specific designs for PA and DWA anchors, the procedure was theoretically assessed for a site off Cozumel Island, Mexico. The results show that the dimensions needed for DWAs are substantially larger than those for PAs. Therefore, whenever drilling is economically and operatively possible, piles would be preferable for the foundations of current turbine systems.

Strength of Modified Foam Concrete-Filled Hollow Section Using Fly Ash as Sand Replacement

Hollow sections for columns, beams and trusses have been used in the steel construction industry for a decade. Concrete-filled hollow section (CFHS) has been widely used due to its aesthetic efficiency and to improve the load-carrying capacity. However, the use of normal concrete as infilled in steel hollow section has increased the dead load of structures. A modified foam concrete filled hollow section using fly ash as sand replacement (FCFHS-FA) is proposed to reduce the structure’s dead weight. This study aims to determine the strength performance of FCFHS-FA structure by using two types of steel hollow section thickness and compare the strength between FCFHS and FCFHS-FA. Steel, preformed foam, and fly ash were used to increase the strength. Nine specimens were prepared and a compression test was conducted. The strength index was calculated to compare the strength of FCFHS with FCFHS-FA. Result shows that FCFHS-FA has a similar strength index compared with FCFHS.

Fundamental Investigations on the Performance of Micro Steel Fibres in Ultra-High-Performance Concrete under Monotonic and Cyclic Tensile Loading

: Ultra-high-performance fibre-reinforced concrete (UHPFRC) can preferably be used for lean and thin-walled structures due to its very high compressive strength. Based on the adverse relation between the increased load bearing capacities and the condensed dead weight of UHPFRC-structures, the impact of live loads in the design gets bigger and, in case of traffic loads, the effects of a cyclic loading have to be considered in more detail. In this context, this study investigated the material behaviour of UHPFRC, especially the tensile fatigue behaviour of high-strength micro steel fibres and the bond behaviour between those fibres and plain UHPC. The test programme included once tensile tests of high-strength micro steel fibres under monotonic and cyclic loading. Based on the test results, an S/N-curve was set up with the characteristic values. Furthermore, the test programme included pullout tests of fibre groups with different embedded lengths and orientations under monotonic and cyclic loading. It was observed that some fibres rupture under certain test configurations like the angle of orientation and the load amplitude.

The Short-Term Performances of Two Independent Gas Modulated Refractometers for Pressure Assessments

Refractometry is a powerful technique for pressure assessments that, due to the recent redefinition of the SI system, also offers a new route to realizing the SI unit of pressure, the Pascal. Gas modulation refractometry (GAMOR) is a methodology that has demonstrated an outstanding ability to mitigate the influences of drifts and fluctuations, leading to long-term precision in the 10−7 region. However, its short-term performance, which is of importance for a variety of applications, has not yet been scrutinized. To assess this, we investigated the short-term performance (in terms of precision) of two similar, but independent, dual Fabry–Perot cavity refractometers utilizing the GAMOR methodology. Both systems assessed the same pressure produced by a dead weight piston gauge. That way, their short-term responses were assessed without being compromised by any pressure fluctuations produced by the piston gauge or the gas delivery system. We found that the two refractometer systems have a significantly higher degree of concordance (in the 10−8 range at 1 s) than what either of them has with the piston gauge. This shows that the refractometry systems under scrutiny are capable of assessing rapidly varying pressures (with bandwidths up to 2 Hz) with precision in the 10−8 range.