Innovative mass timber panels, known as composite laminated panels (CLP), have been developed using lumber and laminated strand lumber (LSL) laminates. In this study, strain distributions of various 5-layer CLP and cross-laminated timber (CLT) were investigated by experimental and two modelling methods. Seven (7) different panel types were tested in third-point bending and short-span shear tests. During the tests, the digital imaging correlation (DIC) technique was used to measure the normal and shear strain in areas of interest. Evaluated component properties were used to determine strain distributions based on the shear analogy method and finite element (FE) modelling. The calculated theoretical strain distributions were compared with the DIC test results to evaluate the validity of strain distributions predicted by the analytical model (shear analogy) and numerical model (FE analysis). In addition, the influence of the test setup on the shear strain distribution was investigated. Results showed that the DIC strain distributions agreed well with the ones calculated by the shear analogy method and FE analysis. Both theoretical methods agree well with the test results in terms of strain distribution shape and magnitude. While the shear analogy method shows limitations when it comes to local strain close to the supports or gaps, the FE analysis reflects these strain shifts well. The findings support that the shear analogy is generally applicable for the stress and strain determination of CLP and CLT for structural design, while an FE analysis can be beneficial when it comes to the evaluation of localized stresses and strains. Due to the influence of compression at a support, the shear strain distribution near the support location is not symmetric. This is confirmed by the FE method.
The goal of this study was to analyze the bearing properties of the differently oriented glulam using digital image correlation (DIC). Six differently oriented specimens associated with three anatomical directions including longitudinal (L), radial (R), and tangential (T), and 12-mm drift pins were used to analyze the bearing properties, including yield load and bearing strength. The highest bearing strength of 22.57 MPa from RL was found, whereas the lowest bearing strength of 6.47 MPa from LR was found. Different strain distributions were observed from the differently oriented bearing specimens using DIC. Different failure ratios of the differently oriented specimens were highly related to the strain distributions. Although the bearing properties were found to be different between the differently oriented specimens, for the connection design aspect, the bearing properties of glulam could be grouped as RL and TL specimens, RT and TR specimens, and LR and LT specimens.
The goal of this study is to evaluate the effect of different sizes of drift pins (12mm, 16mm, 20mm, 30mm) and six orientations of glulam associated with pin positions (RL, TL, LR, TR, LT, RT) on bearing stress and strain distributions of glulam using digital image correlation (DIC). Different bearing stresses, strain distributions, and fracture behaviours associated with the orientation of the glulam and pin sizes were observed. As the diameter of drift pins increased, the bearing strength increased regardless of the orientation. However, the trends of failure behaviours did not change by the pin size.
Guadua angustifolia Kunth (Guadua) is a bamboo species native to South and Central America that has been widely used for structural applications in small and large scale buildings, bridges and temporary structures. Guadua remains a material for vernacular construction associated with high levels of manual labour and structural unpredictability. The aim of this work is to develop standardised industrial structural products from Guadua and to measure and predict their mechanical behaviour. Cross laminated Guadua (CLG) panels comprised of three and five layers were manufactured and their mechanical properties evaluated by testing small and large specimens in compression and shear. The digital image correlation (DIC) method was used to measure strain variations in the X, Y and Z axes on the surface of small CLG panels with strain gauge measurements on the reverse face. The deformation of large CLG panels was measured using DIC on the front face and transducers on the reverse face. The results from mechanical tests and DIC were compared and a finite element (FE) model developed that predicts the response of the material. Overall, this study provides guidelines for structural design with engineered bamboo products which are of key importance for their mainstream use.
The goal of this study was to analyze behavior of the cross-laminated timber (CLT) panel subjected to torsion and develop an efficient procedure for quick verification of numerical model of CLT that subsequently may be used for virtual prototyping of non-standard CLT products. Study used both experiments based on optical measurement using digital image correlation (DIC) and numerical modeling by means of finite element method (FEM). A physical torsion test of the CLT panel was first analyzed in terms of a displacement field that was computed on its surface. The FE simulation of the torsion test followed real boundary conditions and was carried out with use of 2 geometrically different FE models of the CLT. The first FE model did not take into account edgebonding of the lamellas, the second one demonstrated alternative manufacturing option by considering the lamellas’ edge-bonding. The experiment and FE simulations were mutually compared based on displacement paths created on the panel surface. Results showed that the presented procedure offers relatively easy way of verification of FE analyses of CLT. FE model with edge-bonding of lamellas exhibited higher stiffness and higher relative error to DIC measurement than FE model without edge-bonding. Edge-bonding of lamellas introduces influential factor in FE modeling of CLT and should be omitted for accurate and realistic FE analyses of their behavior. Study also showed that lack of orthotropic properties of Oregon hybrid poplar can be in FEA sufficiently substituted by using cottonwood properties. Combining the DIC measurement and FEM in the analysis of the CLT is favorable since it offers an full-field validation of numerical models, which can be subsequently used for virtual prototyping.
This paper presents a new alternative energy dissipation solution to be used with cross-laminated timber (CLT) self-centering walls. CLT is a relatively new building product in North America and could potentially be used for high-rise construction. The development of high-performance seismic design solutions is necessary to encourage innovative structures and the design of these structures to new heights. The objective of this paper is to propose a wall-to-floor connection system that is easy to install and replace (structural fuse) after the occurrence of a large damaging event. The proposed energy dissipators are fabricated following concepts used in developing steel buckling restrained steel braces (BRB), having a milled portion, which is designed to yield and is enclosed within a grouted steel pipe. The connection system is investigated experimentally through a test sequence of displacement-controlled cycles based on a modified version of the test method developed by the American Concrete Institute (ACI) to facilitate development of special precast systems (ACI T1.1-01 Acceptance Criteria for Moment Frames Based on Structural Testing). Digital Image Correlation (DIC) was used to analyze strain behavior of the milled portion, as well as track movement of the panels during quasi-static uniaxial and cyclic testing. The results show the yield behavior and energy dissipation properties of the connection system. Damage was focused primarily in the energy dissipators, with negligible deformation and damage to the CLT panels and connections.