Modeling and Analysis for the Transmission Characteristics of a Proposed Dual-Drive Hydrostatic Lead-Screw System

This paper proposes a novel dual-drive hydrostatic lead-screw system (DDHLS). The design enables a lower feed speed and a better transmission performance than the conventional hydrostatic lead screw (HLS). Considering the nut-misalignment, the lubricating mathematical model of the DDHLS is established based on the perturbation method and solved by the finite difference method. The influences of the nut-radial-displacement, the nut-tilt, and the dual-drivable design on the transmission performance of the DDHLS are researched. The results show the nut-misalignment can regularly reduce or increase the axial load capacity, the axial stiffness coefficient, and the axial damping coefficient. Significantly, the dual-drivable design can improve the axial load capacity and the axial stiffness coefficient while hardly affects the axial damping coefficient.

EFFECT OF ASPECT RATIO ON THE BEHAVIOR OF GFRP-RC CIRCULAR COLUMNS UNDER SIMULATED SEISMIC LOADING

The mechanical and physical properties of glass fiber-reinforced polymer (GFRP) reinforcement are different from steel, which requires independent code provisions for GFRP-reinforced concrete (RC) members. The currently available code provisions for GFRP-RC members still need more research evidence to be inclusive. For example, the available provisions for confinement reinforcement of FRP-RC columns do not consider the effects of column aspect ratio, which is not yet supported by any available research data. In this study, two full-scale spirally reinforced GFRP-RC circular columns were constructed and tested under concurrent seismic and axial loads. Both specimens had an aspect ratio (shear span-to-diameter ratio) of 7.0, while other two specimens with an aspect ratio of 5.0, from a previous stage of this study, were included for comparison purposes. For each aspect ratio, each specimen was loaded under one of two levels of axial load; 20 or 30% of the axial load capacity of the column section. All test specimens had a 35 MPa concrete compressive strength, 350-mm diameter, 85-mm spiral pitch and 1.2% longitudinal reinforcement ratio. The experimental results were analyzed in terms of hysteretic response, drift capacity and inelastic deformability hinge length. Based on the experimental results, it can be concluded that the aspect ratio affects the magnitude of secondary moments and inelastic deformability hinge length. In addition, the aspect ratio may affect drift capacity of GFRP-RC columns, depending on axial load level.

Load-Carrying Capacity of Compressed Wall-Like RC Columns Strengthened with FRP

The analytical prediction of the effectiveness of fiber-reinforced polymer (FRP) in the confinement of a rectangular reinforced concrete (RC) column with a high aspect ratio (wall-like) still has an uncertain solution. In this paper, a numerical investigation of the axial response of RC wall-like columns strengthened with FRP systems was developed. Analytical solutions proposed in the literature for the assessment of the axial load capacity were presented and compared with each other and with the available experimental results. Moreover, non-linear finite element analysis was carried out, and the results were discussed, providing a simple model for the assessment of the axial compressive strength of wall-like RC columns strengthened with FRP.

Load and thermal resistance of sandwitched steel-wood composite walling systems infilled with innovative commercial form material

This research investigated the behaviour of sandwich profiled steel sheet composite wall (PSSCW) and oriented strand board composite wall (OSBCW) with infill commercial form material (CFM). The axial load behaviour of PSSCWs and OSBCWs having different height to width ratio and PSS/OSB-CFM connector spacing was analysed based on experimental results of strength, load-deformation response, load-strain development and failure modes. In addition, flexural behaviour of OSBCW and the thermal conductivity tests on PSSCW and OSWCW specimens were carried-out. The axial load capacity of PSSCW/OSSCW was increased by 946% to 1714% compared to walls without in-fill and decreased with the increase of height to width and connector spacing to height ratio. The existing analytical equations were found to over predict the axial load capacity of both PSSCWs and OSBCWs. The recommendation of this research will understand the axial, flexural and thermal behaviour of PSSCW/OSBCW with CFM infill for practical building applications.

Load and thermal resistance of sandwitched steel-wood composite walling systems infilled with innovative commercial form material

This research investigated the behaviour of sandwich profiled steel sheet composite wall (PSSCW) and oriented strand board composite wall (OSBCW) with infill commercial form material (CFM). The axial load behaviour of PSSCWs and OSBCWs having different height to width ratio and PSS/OSB-CFM connector spacing was analysed based on experimental results of strength, load-deformation response, load-strain development and failure modes. In addition, flexural behaviour of OSBCW and the thermal conductivity tests on PSSCW and OSWCW specimens were carried-out. The axial load capacity of PSSCW/OSSCW was increased by 946% to 1714% compared to walls without in-fill and decreased with the increase of height to width and connector spacing to height ratio. The existing analytical equations were found to over predict the axial load capacity of both PSSCWs and OSBCWs. The recommendation of this research will understand the axial, flexural and thermal behaviour of PSSCW/OSBCW with CFM infill for practical building applications.

Comparative Study on Static Characteristics of Double-Pad Inwardly and Outwardly Pumping Water-Lubricated Spiral-Groove Thrust Bearings

The purpose of this technical brief is to investigate comparatively the static characteristics of the double-pad inwardly pumping and outwardly pumping water-lubricated spiral-groove thrust bearings (SGTBs). Firstly, a thermo-hydrodynamic lubrication model including the cavitating, centrifugal, and turbulent effects is established for the double-pad water-lubricated SGTB operating at a high-speed condition. Subsequently, the film thickness and volume flowrate are verified by an experimental study for the high-speed water-lubricated SGTBs. Finally, the effects of the operating conditions and configuration parameters on the static characteristics of the double-pad inwardly pumping and outwardly pumping SGTBs are analyzed systematically. The simulated results show that when the radius ratio exceeds 0.7, the outwardly pumping SGTB can perform better than the inwardly pumping version, with good axial load capacity, higher resistance to tilting and always positive radial flowrate.