Papers by Keyword: Lateral Confinement

Abstract: The compressive strength and ductility of concrete can be considerably improved by lateral confinement. In this study, an emergency seismic retrofit technique using lashing belt prestressing is used as to manually retrofit damaged reinforced concrete (RC) columns. The initial prestressing is an important aspect of this technique and is introduced by the ratchet buckle. Thus, this technique offers active and passive confinement as well as shear strengthening. Furthermore, diagonal cracks in the damaged RC columns can be closed by using the active confinement of lashing belts, and the lateral and vertical load-carrying capacity and ductility of the damaged RC columns are recovered. In this study, the recovered axial compression capacity of the retrofitted RC columns and repaired RC columns using epoxy resin was investigated. Finally, the hysteretic behavior of the shear-damaged RC columns after the proposed emergency retrofit was investigated.

Abstract: Concrete is a brittle material which cracks under the tension and pulverized when the compressive stress exceeds the ultimate compressive strength. Confined concrete performs better than that of concrete without confinement in resisting penetration. Based on the Griffith strength theory, a quasi-static cylindrical cavity expansion model for the penetration of steel-tube-confined concrete targets is proposed. Numerical results show that ratio of tube wall thickness to tube radius significantly effects cavity expansion stress, which is in proportion to the former ratio. The results are in good agreement with the cavity expansion process.

Abstract: Confined concrete is superior to the normal concrete in anti-projectile performance. The concrete filled confining tube of relatively small radius would be in cracked-comminuted stage during the penetrating process of projectiles at relatively low velocity. Based on the linear pressure-volumetric strain relationship and the Mohr-Coulomb yield criterion, a dynamic cylindrical cavity expansion model for the penetration into confined concrete targets with lateral elastic confinement is proposed. Numerical results show that the lateral confinement improves cavity stress significantly, and the radius ratio of target to cracked-comminuted interface has little influnce on cavity stress for relatively low cavity expansion velocity.

Abstract: The anti-projectile performance of the confined concrete is better than that of the normal concrete. When the radius of the confining tube is relatively small, the confined concrete would be in comminuted stage during the penetrating process of projectiles. Based on the assumption that comminuted concrete materials obey Griffith strength theory, a finite cylindrical cavity expansion model for confined concrete targets is proposed. Numerical results show that the lateral confinement affects little on the cavity stress for relatively small confining rigidity, and the cavity stress increases significantly with the increase of the radius ratio of cavity to confining tube for relatively large lateral confining rigidity.

Abstract: Based on using combustion synthesis under high gravity to prepare TiC-TiB₂ composite, the ceramic armour targets were achieved by the heat-shrunk laternal, cover and back confinements of steel sleeves and plates. Ballistic testing showed that under the impact of long-rod tungsten alloy projectile, the low-carbon-steel sleeve failed to laterally confine the ceramic due to its inadequate residual strength, resulting in poor ballistic performance of the ceramic, whereas the medium-carbon-steel sleeve had a sufficient residual strength to support lateral confinement of the ceramic as the long-rod tungsten alloy projectile makes room in the ceramic for its penetration, the confined ceramic could present its real ballistic performance, and the results of ballistic testing promised lateral confinement and cover confinement of high-strength metal would be beneficial to the improvement in ballistic performance of ceramic armour.

Abstract: Based on using combustion synthesis under high gravity to prepare TiC-TiB₂ composite, the ceramic armour targets were achieved by the heat-shrunk lateral, cover and back confinements of steel sleeves and plates. Ballistic testing showed that under the impact of long-rod tungsten alloy projectile, the low-carbon-steel sleeve failed to laterally confine the ceramic due to its inadequate residual strength, resulting in poor ballistic performance of the ceramic, whereas the medium-carbon-steel sleeve had a sufficient residual strength to support lateral confinement of the ceramic as the long-rod tungsten alloy projectile makes room in the ceramic for its penetration, the confined ceramic could present its real ballistic performance, and the results of ballistic testing promised lateral confinement and cover confinement of high-strength metal would be beneficial to the improvement in ballistic performance of ceramic armour.

Abstract: The purpose of this paper is to investigate producing mechanism and distribution laws of remote cracks for geotechnical engineering structure. The fracture modes of geotechnical material containing a hole with different lateral confining pressure coefficients of 0, 0.05, 0.1, 0.15, 0.25, 0.33, 0.75 and 1 were numerically simulated using RFPA2D (rock failure process analysis) code. The results indicate that under a certain confining pressure, three types of cracks, i.e., primary crack, remote crack and shear crack, can be observed simultaneously in the same sample. When the lateral pressure coefficient is satisfied that 0

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