• Steel and Composite Structures
• /
• v.21 no.2
• /
• pp.357-371
• /
• 2016

Column base connections are critical components in steel structures because they transfer axial forces, shear forces and moments to the foundation. Exposed column bases are quite commonly used in low- to medium-rise buildings. To investigate shear transfer in exposed column base plates, four large scale specimens were subjected to a combination of axial load (compression or tension) and lateral shear deformations. The main parameters examined experimentally include the number of anchor rod, arrangement of anchor rod, type of lateral loading, and axial force ratio. It is observed that the shear resisting mechanism of exposed column base changed as the axial force changed. When the axial force is in compression, the resisting mechanism is rotation type, and the shear force will be resisted by friction force between base plate and mortar layer. The specimens could sustain inelastic deformation with minimal strength deterioration up to column rotation angle of 3%. The moment resistance and energy dissipation will be increased as the number of anchor rods increased. Moreover, moment resistance could be further increased if the anchor rods were arranged in details. When the axial force is in tension, the resisting mechanism is slip type, and the shear force will be resisted by the anchor rods. And the shear resistance was reduced significantly when the axial force was changed from compression to tension. The test results indicated that the current design approach could estimate the moment resistance within reasonable acceptance, but overestimate the shear resistance of exposed column base.

• Geomechanics and Engineering
• /
• v.20 no.4
• /
• pp.359-370
• /
• 2020

Prestressed ground anchors are important structural elements in geotechnical engineering. Despite their widespread usage, the design process is often significantly simplified. One of the major drawbacks of commonly used design methods is the assumption that skin friction is mobilized uniformly along an anchor's fixed length, one consequence of which is that a progressive failure phenomenon is neglected. The following paper introduces an alternative design approach - a computer algorithm employing the load-transfer method. The method is modified for the analysis of anchors and combined with a procedure for the derivation of load-transfer functions based on commonly available laboratory tests. The load-transfer function is divided into a pre-failure (hardening) and a post-failure (softening) segment. In this way, an aspect of non-linear stress-strain soil behavior is incorporated into the algorithm. The influence of post-grouting in terms of radial stress update, diameter enlargement, and grout consolidation is included. The axial stiffness of the anchor body is not held constant. Instead, it gradually decreases as a direct consequence of tensile cracks spreading in the grout material. An analysis of the program's operation is performed via a series of parametric studies in which the influence of governing parameters is investigated. Finally, two case studies concerning three investigation anchor load tests are presented.

• Tunnel and Underground Space
• /
• v.28 no.6
• /
• pp.635-650
• /
• 2018

Many people have been recognized that the Korean Peninsula is no longer safe area from the earthquake by the recent earthquakes occurred in the country. The earthquakes that occurred at Pohang and Gyeongju appeared differently from them considered in the seismic design and researches on the seismic design method have been also conducted by many researchers. Studies on seismic loads are mainly focused on existing superstructures, and research involving them has been actively carried out in reality. However, paper regarding structural stability of reinforcement from seismic load such as soil-nails, rock-bolts, ground anchors which were constructed to ensure stability of serviced structure have been published rarely. In this study, ground anchor been effected by static load and seismic load which is settled in the weathered rock is analyzed. Results for static load are obtained from field test and seismic load is from numerical analysis. In this study, the behavioral characteristics of the ground anchor were analyzed by numerical analysis in case of seismic loading based on the result of the in-situ tensile test of the ground anchor settled weathered rock. As a result, settlement of concrete block due to application of tension force for ground anchor occurred as well as following loss of axial force for ground anchor. Also, as bond length and period of seismic load are longer, increasement of displacement is greater.

• Steel and Composite Structures
• /
• v.33 no.3
• /
• pp.357-373
• /
• 2019

Steel storage racks are slender structures whose overall behavior and the capacity depend largely on the flexural behavior of the base-plate to upright connections and on the behavior of beam-to-column connections. The base-plate upright connection assembly details, anchor bolt position in particular, associated with the high-rise steel storage racks differ from those of normal height steel storage racks. Since flexural behavior of high-rise rack base connection is hitherto unavailable, this investigation experimentally establishes the flexural behavior of base-plate upright connections of high-rise steel storage racks. This investigation used an enhanced test setup and considered nine groups of three identical tests to investigate the influence of factors such as axial load, base plate thickness, anchor bolt size, bracket length, and upright thickness. The test observations show that the base-plate assembly may significantly influence the overall behavior of such connections. A rigid plate analytical model and an elastic plate analytical model for the overall rotations stiffness of base-plate upright connections with concentric anchor bolts were constructed, and were found to give better predictions of the initial stiffness of such connections. Analytical model based parametric studies highlight and quantify the interplay of components and provide a means for efficient maximization of overall rotational stiffness of concentrically anchor bolted high-rise rack base-plate upright connections.

• Geotechnical Engineering
• /
• v.11 no.4
• /
• pp.99-110
• /
• 1995

In this study, friction angles on the surface of vertical rigid ground anchor in normally consolidated dry sand were measured by model pullout tests in laboratory. Friction angles were obtained from the normal and shear stresses measured along depth of the anchor stir face by attaching several 2-dimensional load cells. Model tests were conducted under the plane strain state and axial symmetric state. From the results of tests, it was concluded that the maximum friction angle on the anchor surface coincides nearly with the maximum angle of stress obliquity on the plane of zero-extension direction obtained by plane strain compression test. This result was made with regard to the strength anisotropy and stress dependency of sand. It showed that when angle of shear resistance of the sand is applied to the friction angle of the anchor surface, the design capacity could be less than the applied force, thus making the anchor unsafe.

• Steel and Composite Structures
• /
• v.18 no.6
• /
• pp.1451-1464
• /
• 2015

Recently, in recognition of their outstanding structural performance, the use of Concrete Filled Steel Tube (CFT) columns has been increased. New shape welded built-up square tube was developed by the authors for broader usability using thin steel plates which were bent to be L-shaped (Channel) and each unit members were welded to form square steel tube as an cost-efficient use of expensive steel. In addition, since the rib placed at the center of the tube width acts as an anchor; higher load capacity of buckling is achievable. In order to apply the new shape built-up square columns, the structural behavior and stress distribution with parameter width of thickness (b/t), with and without rib were predicted. The New shape welded built-up square tube effectively delayed the local buckling of the steel tube, which led to a greater strength and ductility than regular HSS.

• Geotechnical Engineering
• /
• v.14 no.3
• /
• pp.5-24
• /
• 1998

Two instrumented full scale tieback walls in sand were constructed at to Geotechnical Experimentation Site located on the Texas A 51M University Riversic Measurements were obtained from the one row anchor wall and from the two row at different times during construction. The measured performance of the tieback walls is presented and investigated. The these walls at different construction stage is evaluated with respect to lateral wall. settlement of the ground, bending moment of the wall. axial load distribution and anchor load variation. The fundamental mechanism of a tieback wall in sand is and explained with the measurements.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2022.04a
• /
• pp.237-238
• /
• 2022

The seismic performance of existing reinforced concrete (RC) elements to which seismic design was not applied is questionable. To evaluate the behavior of existing RC columns, column specimens with widely spaced transverse reinforcement and 90-degree hoop anchor hooks as variables were designed. Experimental tests were performed by applying a fixed low axial load and increasing lateral cyclic loads to the specimens. As a result, the hoop spacing and anchor hook angle did not significantly affect the load-displacement relationship and the dissipated energy before failure.

• Journal of the Korean GEO-environmental Society
• /
• v.11 no.12
• /
• pp.27-35
• /
• 2010

The structures built under the groundwater level are affected by the buoyancy force, which is hydrostatic pressure in the up direction. Recently, buoyancy-resistant anchor method has been applied in many cases of the construction of the important structure of large size, which is built under the groundwater level so that it takes high uplift pressure. Even if the construction cost of the method is very high, it surely increases the safety rate. However, the diagnosis of the performance of the buoyancy-resistant permanent anchor and the investigation of resistance mechanism are still insufficient. Especially, the long-term behavior of the anchor has not been studied well due to the difficulty in observation procedure. The contribution of this paper is the establishment of reasonable design methodology. We have measured anchor axial forces for 10 years after the construction, by using an automated measurement and a manual measurement by establishing a load cell in anchor head. Through the data collected from the measurements, we analyze the construction-step behavior of the anchor according to the self-weight variation of the building and the long-term behavior (i.e. movement within 10 years after the construction) of the anchor according to the passage of time.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.12
• /
• pp.1543-1548
• /
• 2011

Structural analysis is performed to design anchor straps for a large-scale-liquefied-natural-gas (LNG) storage tank with corner protection and an inner tank by considering structural integrity. Anchor straps made of 9% nickel steel are attached to the inner tank, corner protection, and concrete raft to prevent the failure of the inner tank during both normal and emergency operating conditions. Two finite element (FE) models were analyzed in this study. One is a stand-alone model of the anchor strap, while the other is an extended model of the substructure of the anchor strap, inner tank, and corner protection. Three-dimensional shell elements are used to effectively assess the bending and axial behavior of structures. The Tresca stress values in each part of the two models are calculated for operation under five different load-condition cases: normal operation, leakage of the LNG, hydro test, and two earthquake conditions.