Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
62,479
result(s) for
"Joints (Engineering)"
Sort by:
Advances in modeling and design of adhesively bonded systems
The book comprehensively charts a way for industry to employ adhesively bonded joints to make systems more efficient and cost-effective Adhesively bonded systems have found applications in a wide spectrum of industries (e.g. , aerospace, electronics, construction, ship building, biomedical, etc. ) for a variety of purposes.
eBook
Influences of roughness and filling degree on the shear strength and damage evolution characteristics of cement-filled joints
The shear resistance of filling joints is an important factor affecting the stability of rock joints. Pressure-shear tests of cement-filled joints were carried out. Combined with the acoustic emission (AE) technique, the effects of normal stress, roughness and filling degree on the shear strength, damage morphology and damage evolution of cement-filled joints were investigated. The results show that with the increase of roughness, the failure mode is more complicated. When the roughness is low, only the bonding surface of the interface between the filler and the joint surface is damaged, and the filling degree has a weak effect on the failure mode. When the roughness is high, with the increase of normal stress and filling degree, the failure of the filled joint is from the joint failure of the bonding surface and the filling material to the serious failure of the bonding surface, the filling material and the joint. The peak shear strength of filled joints is positively correlated with roughness and negatively correlated with filling degree. With the increase of filling degree, the influence of roughness will be weakened by filling material, and the normal stress will amplify the effect of roughness. The evolution characteristics of AE show that the damage degree of filled joints is positively correlated with normal stress and roughness, and negatively correlated with filling degree. The joint surface is damaged locally at first, then failure near the main raised body of the joint, and finally spreads to the whole joint surface.
Journal Article
Behavior of Exterior Beam-Column Connections with Headed Bars under Nonreversible Cyclic Loading
Two large-scale exterior beam-column connections with beam longitudinal headed bars were tested to evaluate their susceptibility to breakout failures. The specimens were designed following the strength and transverse reinforcement detailing provisions in Chapter 15 of ACI 318-19. The variable investigated was the headed bar embedment length, which was determined based on either Chapter 25 of ACI 318-19 or recent research at The University of Kansas, the latter leading to a 22% shorter embedment length. Both specimens exhibited beam flexural yielding, but the specimen with the shorter bar embedment length experienced significantly more connection damage, followed by a concrete breakout failure. Based on the limited test results, it is recommended that nominal joint shear strength be calculated based on a joint effective depth equal to the headed bar embedment length and a shear stress of 1.0[lambda][??] MPa (12 [lambda][??] psi). A method for calculating headed bar group anchorage strength in exterior beam-column connections was proposed, which led to reasonable and conservative strength estimates in the test specimens. Keywords: anchorage; bar groups; breakout strength; development length; joints; shear.
Journal Article
Pressure-relief joints of initial support structural system used in tunnels with high-stress surrounding rock
To address the problem of large deformations in weak surrounding rock tunnels under high ground stress, which cause damage to initial support structures, this study proposes a novel type of circumferential pressure-relief joint based on the concept of relieving deformation pressure of the surrounding rock. Key parameters of the pressure-relief joint, such as initial bearing capacity peak, constant bearing capacity, and allowable pressure-relief displacement, were obtained through numerical simulations and laboratory experiments. A comparison was made between the mechanical characteristics of rigid joints and the new type of pressure-relief joint. The applicability of the pressure-relief joint was verified through field tests, monitoring the surrounding rock pressure, internal forces in the steel frames, and the convergence displacement of the support structure. The results show that: (1) In the elastic stage, the stiffness of the new pressure-relief joint is similar to that of rigid joints. In the plastic stage, rigid joints fail directly, whereas the pressure-relief joint can control deformation and effectively release the deformation pressure of the surrounding rock while providing a constant bearing capacity. (2) The right arch foot in the experiment had poor rock quality, leading to high stress in the steel frame and significant horizontal displacement. After the deformation of the pressure-relief joint, the stress in the surrounding rock and steel frame significantly reduced, and the rate of horizontal deformation of the support structure slowed down. (3) The vertical and horizontal final displacements of the pressure-relief joint in the experiment were 61mm and 15mm, respectively, which did not exceed the allowable deformation values. The components of the support structure remained intact, ensuring safety. However, this study has limitations: the design of the new pressure-relief joint only allows for a vertical deformation of 150mm and a horizontal deformation of 50mm, limiting the range of pressure-relief deformation.
Journal Article
Analysis of the effect of joint roughness on the failure mechanism of jointed rock mass under direct shear loading
The mechanical properties of jointed rock bodies are important in guiding engineering design and construction. Using the particle flow software PFC2D, we conducted direct shear test simulations on joints with various inclinations and five different roughness levels to examine the models’ crack extension penetration paths, damage modes, and strength characteristics. The findings indicate that the direction of the joint influences the pattern of the rock crack and its penetration route. Under forward shear, the rock bridge creates a notched through surface, whereas under reverse shear it creates two adjacent through surfaces, categorised into four types of crack consolidation between joints with different inclinations: ‘end to end’, ‘the end is connected to the middle’, ‘end connection’, ‘first outward expansion and then rock bridge destruction’. Variations in joint inclination and roughness can alter the mechanical properties and damage patterns of joint specimens. The ‘climbing’ and ‘gnawing’ effects determine the peak shear strength of the rock body at the joint section. It is vital to consider these factors when assessing the joint’s characteristics. The damage effect is determined by the joint inclination and joint roughness. When the main damage effect changes from ‘creeping’ slip to ‘gnawing’ damage, increasing joint roughness enhances the shear strength. Nevertheless, under the same ‘gnawing’ damage effect, augmenting joint roughness weakens the mechanical properties of the rock bridge, and as roughness increases, the shear strength decreases. For example, at a joint inclination of 30°, the shear strength increases by 20.1% as the JRC (Joint Roughness Coefficient) increases from 0 to 5. At a joint inclination of 60°, the shear strength decreases by 10.7% as the JRC increases from 0 to 10.
Journal Article
Uncovering the Damage Mechanism of Different Prefabricated Joint Inclinations in Deeply Buried Granite: Monitoring the Damage Process by Acoustic Emission and Assessing the Micro-Evolution by X-Ray CT
This study reveals the damage mechanisms and fracture evolution characteristics of deeply buried granite with prefabricated joints (inclinations of 0°, 30°, 45°, 60°, and 90°) using uniaxial compression tests monitored by Acoustic Emission (AE) technology. Three-dimensional X-CT technology was used to analyze post-damage fracture evolution in specimens with varying joint inclinations. The results show that the stress–strain curve of deeply buried jointed granite under uniaxial compression includes three stages: initial compaction, crack extension, and failure. AE characteristics align with these stages, showing clear stress responses and timing features. In the initial compaction stage, micro-crack closure dominates, with smaller joint inclinations showing stronger closure effects. In the crack extension stage, joint inclination determines the crack propagation mode. In the failure stage, joint inclination significantly affects the spatial distribution of the rupture network by altering stress concentration areas and crack types. The proportion of shear micro-cracks increases with joint inclination, and peak strength rises with increasing joint angle, potentially accelerating micro-crack evolution. These findings provide valuable insights for designing excavation and instability monitoring in deeply buried multi-jointed granite underground projects.
Journal Article
Damage Characteristics of a Step Lap Joint Exposed to Flexural Loading for Its Different Configurations
Step lap joints are kinds of lap structures, where butted laminations of each layer are consecutively offset in succeeding layers in the same direction. They are mainly designed this way to reduce the peel stresses at the edges of the overlap area observed in single lap joints. In their service, lap joints are often subjected to bending loads. However, the performance of a step lap joint under flexural loading has not been studied in the literature yet. For this purpose, 3D advanced finite-element (FE) models of the step lap joints were developed via ABAQUS-Standard. DP 460 and A2024-T3 aluminum alloy were used for the adhesive layer and adherends, respectively. The polymeric adhesive layer was modelled using cohesive zone elements with quadratic nominal stress criteria and power law interaction of the energies to characterize the damage initiation and damage evolution, respectively. A surface-to-surface contact method with a penalty algorithm and a hard contact model was used to characterize the contact between the adherends and the punch. Experimental data were used to validate the numerical model. The effects of the configuration of the step lap joint on its performance in terms of the maximum bending load and the amount of energy absorbed were analyzed in detail. A step lap joint with three steps (three-stepped lap joint) was found to show the best flexural performance, and when the overlap length at the upper and lower steps was increased, the amount of energy absorbed by the joint increased markedly.
Journal Article
Rehabilitation of Exterior Beam-Column Joint by Geopolymer Mortar under Quasi-Static Loading
Most of the studies conducted on the rehabilitation of reinforced concrete (RC) beam-column joints are on pre-1970 structures. Recently, it was reported that seismically designed beam-column joints might also suffer damage under lateral loading. On the other hand, there is an increasing interest among researchers to study the effectiveness of geopolymer as an alternative repair material. To date, no study has been conducted to examine the performance of geopolymer for the rehabilitation of seismically detailed beamcolumn joints following the removal and replacement method under cyclic loading. In the present investigation, two groups of exterior beam-column joints with different flexural strength ratios were rehabilitated with geopolymer mortar. For comparison, another set of beam-column joints (one from each group) were rehabilitated with cement mortar following the same rehabilitation technique and testing. Test results indicated that geopolymer rehabilitated specimens exhibited 20 to 21% higher initial stiffness, 19 to 22% higher displacement ductility, 24 to 37% higher cumulative energy dissipation, 14 to 17% higher initial equivalent viscous damping ratio, 21 to 26% higher ultimate equivalent viscous damping ratio at failure, and 10 to 14% lower damage index compared to specimens rehabilitated with cement mortar. However, irrespective of repair material, removal and replacement technique was only able to partially restore the cyclic performance of rehabilitated specimens. Keywords: beam-column joint; cyclic loading; geopolymer; removal and replacement method; seismically detailed.
Journal Article