Experimental study on notched connectors for glulam-lightweight concrete composite beams

Abstract

A new type of structural element, the timber-concrete composite beam, exhibited excellent structural performance. The notched connector is widely used in timber-concrete composite systems as a result of its considerable shear capacity and stiffness. Six groups of push-out tests were performed to investigate the shear performance of the notched connectors for the timber-concrete composite beams, with consideration to the varying concrete types, the shear length of the timber, and whether the notch was reinforced. From the test results, the notched connectors that corresponded to the shear fracture of concrete or timber had a low shear capacity and poor ductility. Notched connectors that simultaneously failed at the concrete slab (via shear force), as well as at the lag screw reinforcement point during bending presented the greatest shear capacity. This was followed by the notched connectors that exhibited diagonal-compression failure at the concrete slab. Screw fasteners in the notch were shown to improve the strength, ductility, and post-peak behavior of the notched connectors. In addition, the concrete type, the shear length of the timber, and whether the notch was reinforced were found to have no major influence on the slip modulus of the notched connectors.

Shear stiffness of notched connectors in glue laminated timber-concrete composite beams under fire conditions

“…In Table 5, the effects of concrete strength, notch length, notch width, timber sheared length, and steel fasteners on the notched connectors shear stiffness can be observed. From the experimental results of Yeoh et al (2008), Thai et al (2020), andJiang et al (2020), it can be concluded that screw diameter, screw length, and the presence of a screw did not noticeably affect the connectors' shear stiffness within the investigated range. The research data of Yeoh et al (2008) and Jiang et al (2020) showed that timber sheared length had little influence on the connectors' shear stiffness.…”

“…From the experimental results of Yeoh et al (2008), Thai et al (2020), andJiang et al (2020), it can be concluded that screw diameter, screw length, and the presence of a screw did not noticeably affect the connectors' shear stiffness within the investigated range. The research data of Yeoh et al (2008) and Jiang et al (2020) showed that timber sheared length had little influence on the connectors' shear stiffness. The experimental results from this study suggested that the variation of notch length between 150 and 250 mm did not remarkably affect the connectors' shear stiffness.…”

Load-carrying capacity of self-tapping lag screws for glulam-lightweight concrete composite beams

“…The theoretical results from different models were compared with the push-out test results in this paper and the previously published test results (Deam et al 2008;Oudjene et al 2013;Jiang et al 2016), as shown in Table 4. It can be concluded that the timber-timber and steel-timber calculation models proposed in EN 1995-1-1 (2014) make a conservative prediction on the load-carrying capacity of lag screw connectors.…”

“…A comparison was made between the specimens using normal concrete and lightweight concrete, and their test results showed that the concrete type had no obvious effect on the short-term and long-term performance of the connectors. Deam et al (2008) and Jiang et al (2016) performed push-out tests on coach screw connectors in TCC beams, and the test results showed that the shear performance of screw connectors was mainly influenced by the bearing area. The embedment strength of dowel-type connectors and the bending stiffness of the timber were investigated (Sawata and Yasumura 2002;Gaff et al 2015).…”

Review of connections for timber-concrete composite structures under fire

“…Notched connectors are made by cutting notches into wood beams and filling them with concrete. Yeoh et al (2008Yeoh et al ( , 2011 and Jiang et al (2019Jiang et al ( , 2020 carried out shear tests of notched connectors in TCC beams at room temperature, which showed that notched connectors were one of the best shear connectors, and also one of the most effective and cost-saving connectors. If the notch is used as the main connector, most of the shear force is transmitted through the compression surface of concrete and wood, which can effectively improve the stiffness of the connector.…”