Abstract
In this paper, tests of plug-pin joints are conducted in order to obtain their mechanical parameters, including semi-rigid property. To solve the difficulties of multi-point displacement measurements for small joints, this investigation proposes a vision-based measurement system based on the principle of binocular stereo vision to improve measurement accuracy. Accurate sub-pixel location is achieved according to a template-matching algorithm based on grayscale. Joint performance, including horizontal bar joint tension and compression, semi-rigidity between horizontal bars and upright rods and bracing tension and compression, is investigated in order to acquire joint failure modes as well as load and displacement (or moment and rotation angle) curves. Through data fitting, multi-linear simplified models are proposed to illustrate the joints’ mechanical performance. This paper also investigates geometric imperfection of temporary member structure with plug-pin joints based on several substructure models and temporary grandstand units using a total station theodolite. The probabilistic models of initial member out-of-straightness and story frame out-of-plumb have been acquired, which can be used into Monte Carlo simulation to create stochastic model of the temporary member structure.
Highlights
Temporary member structures (TMS) are a type of structure composed of slender members and corresponding connection joints
In order to resolve the issue of modeling geometric imperfections for TMS with wedge type joints, the actual data of geometric imperfections are needed to identify the probability distribution which can be considered by Monte Carlo method (Bielewicz, Goórski 2002)
There were 19 tests conducted in the lab, including three for horizontal bar joint tensile strength (HBT), three for horizontal bar joint compression (HBC), four for positive semi-rigidity between horizontal bars and vertical rods (PSR), three for negative semi-rigidity between horizontal bars and vertical rods (NSR), three for bracing tension (BTT) and three for bracing compression (BCT)
Summary
Temporary member structures (TMS) are a type of structure composed of slender members and corresponding connection joints. Traditional displacement sensors, such as linear variable differential transformers (LVDT), require a stationary platform as the measurement reference For this wedge-type joint, the arrangements of two or three LVDTs are difficult, so the non-contact measurement method is a newer and better option to conduct to these joint tests. In order to resolve the issue of modeling geometric imperfections for TMS with wedge type joints, the actual data of geometric imperfections are needed to identify the probability distribution which can be considered by Monte Carlo method (Bielewicz, Goórski 2002) Both of geometric imperfections and joint stiffness are indispensable to establish three-dimensional advanced analysis models of TMS (Chandrangsu, Rasmussen 2011b). A total of 91 measurements of upright rod out-of-straightness and 45 measurements of story out-of-plumb were taken and the corresponding probability distributions acquired
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