排序方式: 共有55条查询结果,搜索用时 9 毫秒
1.
Michael Karantzikis Catherine G. Papanicolaou Costas P. Antonopoulos Thanasis C. Triantafillou 《Canadian Metallurgical Quarterly》2005,9(6):480-487
The present study investigates experimentally the behavior of concrete confined with fiber reinforced polymers (FRP) in the form of jackets which are applied according to a number of nonconventional techniques. First, the effectiveness of various jacketing configurations combined with anchors as a measure of increasing the strength and deformability of L-shaped columns is investigated. It is concluded that easy to install and low-cost anchors made of resin impregnated fibers properly placed at the reentrant corner of L-shaped columns enable excellent mobilization of confining stresses supplied by the FRP jackets. Next, a number of alternative confinement methods are investigated on concrete cylinders, aimed at quantifying the effectiveness of (1) unbonded jacketing, (2) spirally applied strips attached only at their ends, and (3) jacketing directly on concrete with mortar plastering. Although the study may be regarded as preliminary, it provides useful experimental support to a number of techniques which have the potential to open new horizons in the field of externally applied FRP for enhancing concrete confinement. 相似文献
2.
3.
通过考虑预应力锚索锚固体的抗弯能力,改善数值模拟中预应力锚索的加同效果,以改变大型边坡锚索群加固效果被严重低估的现状,数值试验结果表明,在下一步开挖前,考虑抗弯能力的锚索与不考虑抗弯能力的锚索模型的作用效果完全一致,在下一步开挖后,两种锚索的作用效果出现明显差异,考虑抗弯效果的锚索单元对边坡塑性区、最小主应力的降低及边坡位移的约束效果更加明显。 相似文献
4.
Jacob W. Schmidt Anders Bennitz Bj?rn T?ljsten Henning Pedersen 《Canadian Metallurgical Quarterly》2010,14(4):397-405
A durable and very efficient external strengthening system is achieved if steel tendons for posttensioning applications can be replaced with carbon fiber-reinforced polymer (CFRP) tendons, and if reliable anchorage systems are developed. This paper presents a newly developed and simple-to-use, two-piece wedge anchorage for CFRP tendons with an integrated sleeve and a differential angle between barrel and wedge sections. Three longitudinal slits are cut into the one-piece wedge, with one slit open and the other two stopping 1 mm from the inner wedge hole. The integrated sleeve holds the wedge’s sections together during presetting and loading, resulting in a circumferential confined gripping of the CFRP tendon and optimized surface friction area. Therefore, the one-piece wedge differs from conventional wedge systems, where the wedges act separately with adjacent spaces, wedging the separate tendon sleeve in the longitudinal direction. Evaluation of the failure modes during testing was one of the main keys in achieving an increasingly better performance of the anchorage until the final anchorage was developed. The obtained failure modes are therefore described to enlighten the importance of addressing them when testing. The test setup used and measured behavior are described further together with the loading procedure. The anchorage reached the full capacity of the CFRP tendon and was seen to ensure a stable load of fracture. 相似文献
5.
A. Srirama Rao B. R. Phanikumar R. Dayakar Babu K. Suresh 《Canadian Metallurgical Quarterly》2007,133(5):531-538
Granular pile anchors (GPA) are one of the recent innovative foundation techniques devised for mitigating the problems posed by swelling clay beds. In a granular pile anchor, the footing is anchored to an anchor plate at the bottom of the granular pile. This makes the granular pile tension resistant and enables it to absorb the tensile force caused on the foundation by the swelling clay. An understanding of the amount of uplift resistance offered by the GPA is important in the design of granular pile-anchor foundations in field situations causing tensile forces on foundations, such as in expansive clay beds. This paper presents the results of a field-scale test program conducted to study the pullout response of GPAs embedded in expansive clay beds. Pullout load tests were conducted on GPAs of varying lengths and diameters. It was found from the field pullout load tests that granular pile anchors of larger surface area resulted in higher pullout capacity. Of the various single granular pile anchors with l/d values between 2.5 and 10, the GPA of length 1000?mm and diameter 200?mm (l/d = 5) showed the best pullout load response when tested alone, resulting in a failure uplift capacity of 14.71?kN. Increase in diameter and length of granular pile anchor increased the uplift capacity. When the length of the GPA was increased from 500 to 750 and 1000?mm, the percentage increase in the uplift load required for an upward movement of 25?mm was 33.3 and 55.5% respectively. The pullout load of the GPA when tested under group was 18?kN as against a 12?kN for the GPA when tested single. 相似文献
6.
7.
地下工程桩锚护壁体系的设计、施工及质量控制是一个比较复杂而且条件多变的系统工程,涉及多学科诸多条件,本文结合四个工程,不同土工物理指标、不同地点、不同深度、不同计算方法、不同的质量控制方法,谈一些自己对设计、施工、信息采集与反馈、控制与决策方面的浅见 相似文献
8.
Ehab A. Ahmed Ehab F. El-Salakawy Brahim Benmokrane 《Canadian Metallurgical Quarterly》2008,12(6):596-607
This paper presents the results of an experimental study conducted on the pullout capacity of glass fiber reinforced polymer (GFRP) postinstalled adhesive anchors embedded in concrete. A total of 90 adhesive anchors were installed using sand-coated GFRP reinforcing bars and tested under monotonic tension loading in accordance with ASTM E-488-96 in 1996. The test parameters were: (1) the GFRP bar diameter (25.4, 15.9, and 6.4?mm); (2) the embedment depth (5, 10, and 15 db where db=bar diameter); (3) the adhesive type (epoxy-based and cement-based adhesives); and (4) installation conditions (wet or partially submerged and dry holes). The tested GFRP adhesive anchors were installed in concrete slabs measuring 3,750?mm long, 1,750?mm wide, and 400?mm deep. The test specimens were kept outdoors for 7?months to be subjected to real environmental conditions including freeze-thaw cycles, wet and dry cycles, and temperature variations. The experimental results indicated the adequate performance of GFRP adhesive anchors installed in wet or partially submerged condition using epoxy-based adhesive. Similar behavior was observed for those installed with cement-based adhesive in dry conditions as well. The capacity of the GFRP bars installed with both adhesive types was achieved at an embedment depth ranging from 10 to 15 db. 相似文献
9.
R. S. Merifield 《Canadian Metallurgical Quarterly》2011,137(7):704-716
In recent years, the use of helical anchors has expanded beyond their traditional use in the electrical power industry. The advantages of rapid installation and immediate loading capability have resulted in their being used in more traditional civil engineering infrastructure applications. Unfortunately, our current understanding of these anchors is unsatisfactory, and the underlying theoretical framework adopted by engineers has proven to be largely inappropriate and inadequate. A better understanding of helical anchor behavior will lead to increased confidence in design, a wider acceptance as a foundation alternative, and more economic and safer designs. The primary aim of this research is to use numerical modeling techniques to better understand multiplate circular anchor foundation behavior in clay soils. A practical design framework for multiplate anchor foundations will be established to replace existing semiempirical design methods that are inadequate and have been found to be excessively under- or overconservative. This framework can then be used by design engineers to confidently estimate the pullout capacity of multiplate anchors under tension loading. 相似文献
10.
The ultimate pullout capacity (UPC) and the shape modification factors of horizontal plate anchors were calculated by using upper-bound limit analysis, in which the assumptions of both a nonlinear failure criterion and the nonassociated flow rule were made upon the soil mass above the anchor plate. Three types of anchor plates, including strip anchors, circle anchors, and rectangle anchors, and the corresponding failure mechanisms are taken into consideration. The anchor breakout factors were obtained according to the principle of virtual power, which was realized numerically by the nonlinear sequential quadratic programming algorithm. The shape modification factors for different kinds of anchors were given through a multiple nonlinear regression method. Numerical experiments demonstrate the validity of the solutions by reducing the solutions (nonlinear criterion and nonassociated flow rule) into their special cases (linear criterion and associated flow rule), which matches well with existing work. The dilation and nonlinearity of soil mass should be considered because it plays a remarkable role in the UPC of anchor plates. 相似文献