The wrapping of fibre-reinforced composite sheets around concrete columns is a promising method for structural strengthening and repair. This rehabilitation technique is of practical interest, as the lay-up of the sheets is rather easy; it does not require specialized tools, and the epoxy resins employed cure at ambient temperatures. Here, results of an experimental investigation are reported for 16 round reinforced concrete columns 300 mm in diameter and 1200 mm high. These columns were confined by means of carbon-epoxy sheets and loaded concentrically in axial compression. The effects of various parameters on the structural behaviour of the confined concrete columns are investigated. These parameters included the concrete strength, longitudinal steel reinforcement, steel stirrups, steel corrosion, and concrete damage. The test results show that composite confinement can considerably enhance the structural performance of concrete columns, especially with regard to ductility. The potential to restore the full strength of severely damaged columns is also demonstrated, as retrofitted columns exhibit axial load carrying capacities equal or superior to those of undamaged columns, along with significant increases in ductility. The contribution of the transverse steel reinforcement is seen to be minimal, as long as the stirrup spacing is medium to large. For such cases tests on plain concrete cylinders are sufficient for further investigations of this retrofit method, as the key parameters which really affect strength and ductility are the concrete strength, composite fibre type, and sheet thickness.Key words: fibre composite sheets, confinement, concrete, column repair, rehabilitation, strengthening.
Leiomyosarcoma of the inferior vena cava is a rare malignancy, and radical resection with negative margins remains the only hope for cure. In this report we cite four cases of this tumor treated at The University of Texas M.D. Anderson Cancer Center with particular emphasis on the use of preoperative chemotherapy. In our patients, preoperative chemotherapy did not adversely affect operative outcomes or survival. The potential benefits of preoperative chemotherapy include control of micrometastases, reduction in tumor size before resection, and in situ evaluation of tumor response to chemotherapy for postoperative adjuvant therapy.
An experimental research project was undertaken to evaluate the need to strengthen existing reinforced concrete bridges belonging to the Ministère des Transports du Québec. A typical bridge consisting of a single-span bridge with T-shaped sections was identified. Evaluation of the bridge showed that an increase in bending strength and shear strength would be necessary to satisfy current loading conditions and code requirements. The increase in bending strength was obtained by bonding carbon-reinforced composite materials to the underface of the beams, with fibres in the longitudinal direction. External U-shaped stirrups made of glass-reinforced composite materials were installed on the outside faces of the beams in order to increase their shear strength. This paper presents a selection of experimental results initially obtained on T-section beams, scaled 1:3 with respect to the bridge under consideration. The actual reinforcement scheme selected for the bridge is then presented, accompanied by comments on the construction process. Conventional instrumentation and fibre optic sensors were incorporated to the repair work in order to evaluate the behaviour of the bridge, before and after strengthening. Initial results of this ongoing evaluation are presented here.Key words: bridge strengthening, FRP, composite materials, instrumentation, field testing.
31Through experimental and numerical studies, this research work aims to provide directions 32 on the optimal geometric configuration for single-lap and double-lap bolted connection 33 between aluminum alloy 6061-T6 and steel. From experimental test results, the effects of 34 different geometric parameters on the joint strength were discussed. These parameters include 35 the end-distance, the side-distance, the pitch-distance, the plate thickness and the joint 36 eccentricity. Then, the experimental results were compared to predicted results using design 37 references and geometric recommendations proposed by design references were critically 38 examined. The experimental study was complemented by finite element (FE) analysis to 39 extend the study to a larger range of parameters. In addition to the analysis of the geometric 40 parameters listed above, the effects of the gage-distance on the joint strength were studied in 41 the FE analysis. The experimental and finite element results show that a careful selection of 42 geometric parameters can result in the high improvement of the connection strength and 43 failure mode. Limiting the side-distance to the minimum recommended value was found to 44 limit the strength of a connection with two bolts in a column to that of the one-bolt 45 connection. In most cases, bearing was found to govern the strength of the connections. The 46 calculated bearing strengths were found to underestimate significantly the connection 47 strength. Based on these analyses, maximum geometric parameters beyond which there is no 48 further increase of the joint capacity were evaluated and optimum geometric parameters were 49proposed. 50
30This paper presents the effect of geometric parameters on the behavior of bolted GFRP 31 pultruded plates for civil engineering applications. After a literature review, results of an 32 experimental analysis investigating the behavior of GFRP-to-steel single-lap bolted 33 connections are presented. Then, a finite element analysis validated by experimental data is 34 used to evaluate the effects of the end-distance, side-distance, gage, pitch and plate 35 properties on the strength and failure mode of the connection. A critical examination of 36 geometric recommendations proposed in design references is presented. Bearing failure 37 caused by contact of the bolt on the GFRP plate is usually defined as the preferred failure 38 mode. With highly orthotropic plate, this type of failure was found to be less likely to occur 39 when loading is applied in the pultruded direction. The investigation showed that the 40 minimum end-distance and pitch-distance recommended by design references usually 41 produce a connection with the maximum capacity. However, it was found that the 42 minimum side-distance recommended by these references does not necessarily lead to the 43 maximum capacity for one-bolt and for two-bolt in a column connections. 44
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.