Embedment

About: Embedment is a research topic. Over the lifetime, 2441 publications have been published within this topic receiving 31444 citations.

Fracture mechanics based joint capacity prediction of glued-in rods with beech laminated veneer lumber

Abstract: Glued-in rods (GiR) represent a very successful type of adhesively bonded joints in timber engineering. Despite their apparent geometrical simplicity, their dimensioning still challenges practitioners. A major source of mechanical complexity resides in the orthotropic nature of the wood, or engineered wood products, as laminated veneer lumber (LVL). This paper presents a relatively simple design approach based upon fracture mechanics (FM) and associated double-cantilever beam (DCB) tests that complemented tensile tests for material characterisation. In comparison with the state-of-the-art related to FM in timber engineering, the paper presents a practitioner oriented approach of a yet complex set of GiR geometries involving beech LVL (M16-8.8 threaded rods embedded in cross sections of 120 × 120 mm2 and embedment lengths of 96mm, 128mm and 160mm). The developed numerical model resulted in a good description of the load-displacement of a series of full scale, including very good estimates of their ...

Anchorage Strength and Behavior of Headed Bars in Exterior Beam-Column Joints

Abstract: Headed bars can assist in alleviating steel congestion and are commonly used in areas where development hooks or traditional reinforcement development lengths cannot be achieved. In this study, 30 exterior beam-column joint specimens without transverse reinforcement were tested to measure anchorage strength with respect to anchorage configuration and embedment length. The anchorage behavior of bars terminated with a head and with a 90-degree hook was investigated and compared with each other and existing models. Tensile load was directly applied to the bar and the same amount of compressive load was applied to the compressive zone of an idealized beam. Findings show that existing models based on idealized failure modes do not properly predict the concrete contribution to anchorage strength of headed bars terminated in exterior joints. The anchorage strength of the headed bars consisted of a combination of head bearing and bond. A specific model complying with the given condition of the anchorage zone should be used since failure modes of headed bar anchorage are varied with given geometric and material conditions. A new model is proposed that conservatively estimates the anchorage strength of the headed bars terminated within exterior beam-column joints with sufficient side cover.

Tensile and fatigue investigations of timber joints with glued-in FRP rods

Abstract: Glued-in rods are an effective method to form timber connections that are increasingly in the focus of research. Compared to steel rods, fibre-reinforced polymer (FRP) bars provide higher resistance against corrosion, reduced weight, and lower heat conductivity. Despite excellent mechanical performance, high fire resistance, and improved aesthetics, they are, however, not yet widely used due to lack of design regulation. This is particularly true for cyclic loads, where determination of fatigue characteristics depends upon time-intensive experimental procedures. In this research, 50 glued-in FRP rod specimens with different embedment lengths were manufactured and tested in uniaxial tension: a first set under quasi-static load and a second set under cyclic load. For the fatigue tests, a new approach based on a stepwise load increase was used to estimate fatigue strength, a method that aims at reducing the experimental effort usually associated with Woehler curves. Experimental results indicated tha...

Failure loads for model adhesive joints subjected to tension, compression or torsion

Abstract: The Griffith fracture criterion has been applied to model adhesive joints subjected to tension, compression or torsion. Two model joints are considered: a rigid cylinder partly embedded in and bonded to an elastic cylinder (termed “rod joint” here), and an elastic cylinder inserted partway into, and bonded to, a rigid tube (termed “sleeve joint” here). Both types of joint have been constructed, using vulcanized rubber cylinders bonded to aluminium rods and sleeves.Measurements have been made of the failure loads under tension, compression and torsional loading. They were found to be in satisfactory agreement with the theoretical predictions except, in some instances, for rod joints subjected to tension or torsional loading when the failure loads were as much as three times the predicted values. This discrepancy is attributed to friction between the partially-detached rubber cylinder and the embedded rod, enhanced to a great extent by the tendency of the rubber cylinder to shrink in radius on stretching or twisting. A theoretical analysis of the effect of friction is presented. It predicts increasingly large pull-out forces or torques, as the depth of embedment increases, until frictional seizure occurs. Experimentally, frictional effects were limited by applying an internal gas pressure to the region being detached. All of the failure loads were then found to be in satisfactory agreement with the original theory, ignoring frictional effects. Thus, a simple fracture energy criterion is shown to govern the failure of adhesive joints under complex loading conditions, with or without friction acting at the interface.

Increased suture embedment in tendons: an effective method to improve repair strength.

Abstract: We evaluated the effect of length of suture embedment within tendons on the tensile strength of repaired tendons. Thirty fresh pig flexor tendons were divided into three groups and subjected to repairs with the Halsted tendon sutures in which 1/3, 1/2, and 2/3 of the length of the longitudinal sutures was embedded within the tendons. The repaired tendons were pulled to complete failure by an Instron tensile testing machine. The 2 mm gap-formation force, ultimate strength, stiffness, and energy to failure were greatest when 2/3 of the suture length was embedded within the tendon. The results indicate that suture embedment is an important contributor to the tensile properties of the repair, and that increase in length of suture embedment is an effective way to strengthen tendon repairs.