13 research outputs found
Environmental degradation of structural glass systems: A review of experimental research and main influencing parameters
Get PDFSeveral factors, including incentives associated with aesthetics, transparency, high chemical, and mechanical durability, and its excellent corrosion resistance, have rapidly accelerated the interest and use of glass as windows, façades, or load-bearing elements in structural applications. Nonetheless, the glass is chemically attacked when subjected to certain environmental conditions and its chemistry, structure, as well as its optical and mechanical properties, are altered by the different weathering processes throughout its service life. Several techniques exist for evaluating the performance of weathered glass. These include both natural and artificial ageing techniques. However, little correlation has been shown to exist between natural and artificial ageing, especially the comprehensive comparison between the naturally aged and artificially weathered glazing systems have yet to be examined. In this review paper, the weathering of structural glass systems when exposed to environmental conditions is presented. Emphasis in the literature has been placed chiefly on the different types of glazing in the construction industry and their resistance to three main weathering agents: humidity, temperature, and soiling. Main optical and mechanical tests reported in the literature are summarized, and the properties described in each of them are examined, providing evidence of current challenges, limitations, and insight on future prospects
Load bearing capacity of glass fins and T-beams subjected to static and cyclic loads
No full textNowadays there are examples of structures made of glass only. It is progressively being used
in building construction as load bearing elements. Glass is brittle and has an unusual behaviour
when loaded. The aim of this paper is to study the performance of glass fins and T-beams under
two loading conditions namely, static and cyclic loads. The cyclic load that was controlled by
constant displacement rate was applied for few loading stages. The displacement rate was
increased by 0.5mm at each loading stage. Three-point flexure testing method was adopted to
determine the ultimate breaking load of these glass structures. The ultimate bending strength
of glass T-beam is approximately 74% higher than that of glass fin. The load-displacement
response of both types of glass structures is non-linear. Under the combination of pre-cyclic
and static loads, the bending strength of glass fin and T-beams is 40% and 24% lower than that
of the glass structures under static load only, respectively. The bending strength of glass
structures reduced significantly when the glass was initially loaded. From this study, it was found
that the strength of the glass structures is influenced by the repetitive or cyclic loads
XFEM modelling in multi-bolted joints using a unified bolt preload
No full textMulti-bolted joints are adopted and designed to provide efficient load transfer within assembled engineering parts. Bearing failure is favorable during design phase due to more progressive failure mode, however, ability of by-pass stress to be transferred to adjacent bolts in multi-bolted joints prone to catastrophic net-tension failure. Former approach known as equivalent spring stiffness (ESS) was proposed but it requires experimental sliding load value. This has led to semi-empirical approach to require experimental set-up than incorporating a generic bolt preload value. This paper aims to provide a unified bolt preload (UBP) value to be implemented in each bolt independent upon plate properties and bolts arrangements. Strength prediction were taken place by 3-D Extended Finite Element Method (XFEM) framework of various staggered and non-staggered arrangements to include various lay-ups types and plate thickness. The failure loads predictions in each testing series were investigated and then validated against experimental datasets and also compared with previous technique (ESS approach). Crack patterns and failure modes from this approach were consistent with experimental observations, where net-tension failures were observed within all testing series. Less good prediction compared to from ESS technique, partly due to semi-empirical nature in former approach. Nevertheless, reasonable agreement in UBP technique with experimental datasets were obtained (average discrepancy of approximately 20%)
Glass Stiffness Contribution of Flat and Curved Cable-net Supported Glass Façade Systems
No full textVision-based experimental study of force estimation in the cable-stayed bridge’s cable model
No full textIn this paper, a vision-based measurement is proposed, so as to realize quick and convenient tests on the cable force of single-cable plane cable-stayed bridge. Firstly, laser is used to lay out the reference points, and pictures are taken by mobile phone or camera, gaining cable sag by serial image processing. The next step is to calculate the cable force by its relation with sag. According to laboratory test of cable force, the measuring error of cable force is within 3%, which meets the engineering precision requirements. This simple, efficient and low-risk method is easy to operate, and can solve the difficulty of marker installation during visual measurement
Performing laboratory study of the behavior of reactive powder concrete on the shear of RC deep beams by the drilling core test
No full textIn the past decade, it has been observed that the applications of modern materials have developed a lot, especially effective reactive powder concrete (RPC), due to its superior performance properties. As a result of the superior resistance of RPC, it will give a longer construction life with less maintenance and more resistance to various environmental conditions and exhibits high-performance features such as high porosity, very high strength, and excellent corrosion resistance. The parameters studied in the present research were used to investigate the effect of maximum load, deflection, tensile and strain of concrete, first shear crack, crack pattern, and crack width. Considering the aforesaid cause and objective, one specimen of RPC RC deep beams has a rectangular cross-section of 150 mm in width, 500 mm in depth, and a total length of 1.2 m. One control specimen was tested for comparison. Moreover, 12 control specimens including cylinders and cubes were cast and tested to obtain the mechanical properties of the normal and RPC deep beams. Following the specimens’ processing, they were subjected to two concentrated load pressure tests through a hydraulic jack. Based on the results, the ultimate strength, deflection, and first shear crack capacity for the reactive powder concrete deep beam (RPCDB) have increased by 68, 10.5, and 62.5%, respectively, compared with concrete deep beam (CDB). Moreover, with respect to the width, the delay in the appearance of the first shear crack was reduced by 11 and 78%, respectively, compared with CDB at 65% of the final shear load. In addition, regarding the stress-strain results, RPCDB has increased by 118% at the maximum stress compared with CDB and in contrast, the strain scores for CDB increased by 22.5% at maximum stress compared to RPCDB
A Pre-Process Enhanced Digital Image Correlation Approach for Smart Structure Monitoring
No full textThis research provides a practical guideline for Digital Image Correlation (DIC) data variations minimization in structural engineering through simple image processing techniques. The main objective of this research is to investigate the Pixel Averaging (P.A.) effect on the differential strain Diff(εx) variations. Three concrete arches were tested with three-point bending using the DIC technique for strain measurements. The measured strains are obtained through two virtual horizontal extensometers in the middle of each arch. The Diff(εx) was selected to avoid other 2D-DIC issues, such as the sample-camera out-of-plane movement. Three image cases, namely, one, ten, and twenty averaged images, were used for DIC analysis of each arch. The conditions of each image case are assessed by computing the Diff(εx) variance and the linear least square criterion (R2) between the two extensometers. The second objective is to examine the speckles’ dilation effects on the speckle pattern density and surface component quality utilizing the Image Erode (I.E.) technique. The (P.A.) technique provided consistent differential strain Diff(εx) values with a variance reduction of up to (90%) when averaged images were used. The (R2) has considerably increased (from 0.46, 0.66, 0.91 to 0.90, 0.96, 0.99), respectively, for the three samples. Moreover, the (I.E.) technique provided qualitatively denser speckles with a highly consistent DIC surface component
Experimental performance of the cable-net structure supported glass systems with cable damages
No full textAn experimental investigation into the characteristics and performance of reactive powder concrete to choose the ideal mix
No full textreactive Powder Concrete (RPC) originated in the early 1990s as a cutting-edge concrete material renowned for its outstanding strength, durability, and ductility. Its remarkable durability attributes stem from a low water-cement ratio, high density, and elevated strength. With high ductility, RPC exhibits significant deformation capabilities before reaching failure. Additionally, its low porosity contributes to reduced material permeability, enhancing resistance against chemical attack and water infiltration. The primary goal of this experimental investigation is to choose an ideal mix for reactive powder concrete after implementing several experimental mixes based on mixing ratios implemented during previous studies to choose the optimal mix. Subsequently, the chosen mixture underwent testing at 7 days to assess its behavior and mechanical properties, utilizing six standard cylindrical specimens (10*20) cm and six cubes (15*15) cm. The results demonstrated a substantial increase in the ultimate compressive strength of the (RPC) specimen by 72% compared to the Normal Concrete (NC) specimen. Moreover, the tensile strength of the RPC exhibited a 35.4% increase compared to the (NC) specimen. The stress-strain analysis indicated a remarkable 118% increase in the (RPC) specimen's maximum stress compared to the (NC) counterpart. In contrast, the strain values for ordinary concrete rose by 22.5% at the point of maximum stress compared to the RPC specimen. Specifically, the tensile stress of the (RPC) specimen increased by 10% compared to the (NC), accompanied by a 29% uptick in tensile strain for the RPC specimen at the point of maximum stress. Furthermore, the (RPC) specimen demonstrated a 38.2% increase in the Modulus of Elasticity and a 35.7% increase in Poisson's ratio compared to the (NC) specimen
A Digital Image Correlation Technique for Laboratory Structural Tests and Applications: A Systematic Literature Review
No full textDigital image correlation (DIC) is an optical technique used to measure surface displacements and strains in materials and structures. This technique has demonstrated significant utility in structural examination and monitoring. This manuscript offers a comprehensive review of the contemporary research and applications that have leveraged the DIC technique in laboratory-based structural tests. The reviewed works encompass a broad spectrum of structural components, such as concrete beams, columns, pillars, masonry walls, infills, composite materials, structural joints, steel beams, slabs, and other structural elements. These investigations have underscored the efficacy of DIC as a metrological instrument for the precise quantification of surface deformation and strain in these structural components. Moreover, the constraints of the DIC technique have been highlighted, especially in scenarios involving extensive or complex test configurations. Notwithstanding these constraints, the effectiveness of the DIC methodology has been validated as a strain measurement instrument, offering numerous benefits such as non-invasive operation, full-field measurement capability, high precision, real-time surveillance, and compatibility with integration into other measurement instruments and methodologies
