• Earthquakes and Structures
• /
• v.6 no.2
• /
• pp.181-199
• /
• 2014

The infill walls, whose contribution to the earthquake resistance of a structure is generally ignored due to their limited lateral rigidities, constitute a part of the lateral load bearing system of an RC frame structure. A common method for improving the earthquake behavior of RC frame structures is increasing the contribution of the infill walls to the overall lateral rigidity by strengthening them through different techniques. The present study investigates the influence of externally bonded perforated steel plates on the load capacities, rigidities, and ductilities of hollow brick infill walls. For this purpose, a reference (unstrengthened) and twelve strengthened specimens were subjected to monotonic diagonal compression. The experiments indicated that the spacing of the bolts, connecting the plates to the wall, have a more profound effect on the behavior of a brick wall compared to the thickness of the strengthening plates. Furthermore, an increase in the plate thickness was shown to result in a considerable improvement in the behavior of the wall only if the plates are connected to the wall with closely-spaced bolts. This strengthening technique was found to increase the energy absorption capacities of the walls between 4 and 14 times the capacity of the reference wall. The strengthened walls reached ultimate loads 30-160% greater than the reference wall and all strengthened walls remained intact till the end of the test.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.03a
• /
• pp.1188-1194
• /
• 2008

As computation technologies has developed, the analysis using load transfer is mainly performed. But most of the functions used in the above program has been developed in foreign countries. Also in our nation, lots of studies concerning load transfer are being researched. The investigation of suitability about the piles installed in our grounds, however, is required as functions acquired experientially, basing on the piles installed in foreign grounds. In this background, the load transfer curve required to use load transfer method on its design through the analysis of field tests inside our nation intends to be made, on which this research focuses.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.03a
• /
• pp.539-550
• /
• 2009

As computation technologies has developed, the analysis using load transfer is mainly performed. But most of the functions used in the above program has been developed in foreign countries. Also in our nation, lots of studies concerning load transfer are being researched. The investigation of suitability about the piles installed in our grounds, however, is required as functions acquired experientially, basing on the piles installed in foreign grounds. In this background, the load transfer curve required to use load transfer method on its design through the analysis of field tests inside our nation intends to be made, on which this research focuses.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.760-766
• /
• 2008

As computation technologies has developed, the analysis using load transfer is mainly performed. But most of the functions used in the above program has been developed in foreign countries. Also in our nation, lots of studies concerning load transfer are being researched. The investigation of suitability about the piles installed in our grounds, however, is required as functions acquired experientially, basing on the piles installed in foreign grounds. In this background, the load transfer curve required to use load transfer method on its design through the analysis of field tests inside our nation intends to be made, on which this research focuses.

• Computers and Concrete
• /
• v.24 no.3
• /
• pp.223-236
• /
• 2019

Experience of previous earthquakes shows that a considerable portion of concrete precast buildings sustain relatively large damages especially at the beam-column joints where the damages are mostly caused by bar slippage. Precast concrete buildings have a kind of discontinuity in their beam-column joints, so reinforcement details in this area is too important and have a significant effect on the seismic behavior of these structures. In this study, a relatively simple and efficient nonlinear model is proposed to simulate pre- and post-elastic behavior of the joints in usual practice of precast concrete building. In this model, beam and column components are represented by linear elastic elements, dimensions of the joint panel are defined by rigid elements, and effect of slip is taken into account by a nonlinear rotational spring at the end of the beam. The proposed method is validated by experimental results for both internal and external joints. In addition, the seismic behavior of the precast building damaged during Bojnord earthquake 13 May 2017, is investigated by using the proposed model for the beam-column joints. Damage unexpectedly inducing the precast building in the moderate Bojnord earthquake may confirm that bearing capacity of the precast building was underestimated without consideration of joint behavior effect.

• Steel and Composite Structures
• /
• v.47 no.6
• /
• pp.679-691
• /
• 2023

The application of short, fiber-reinforced polymer composite pipes has been increasing rapidly. A comprehensive review of the prior research reveals that the majority of the previously-reported studies have been conducted on the filament-wound composite pipes, and fewer studies have been reported on the mechanical behavior of short, randomly-oriented fiber composite pipes. On this basis, the main objective of this research endeavor is to investigate the mechanical behavior and failure modes of short, randomly-oriented glass-fiber composite pipes under three-point bending tests. To this end, an experimental study is performed in order to explore the load-bearing capacity, failure mechanism, and deformation performance of such pipes. Fourteen properly-instrumented composite pipe specimens with different diameters, thicknesses, lengths, and nominal pressures have been tested and also simulated using the finite element approach for verification purposes. This study demonstrates the effectiveness of the diameter-to-thickness ratio, length-to-diameter ratio, and nominal pressure on the mechanical behavior and deformation performance of short, randomly-oriented glass-fiber composite pipes.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.05a
• /
• pp.385-386
• /
• 2023

In this application study, field pilot tests were performed to evaluate the validity of a proposed formula between the exerted electrical energy and SPT N-value based on the result of the basic study. Measurement sensors and recording system were developed to obtain exerted motor current and drilling depth in a field. By using the correlation formula proposed in the basic study, the measured motor current and boring speed were applied to predict SPT N-value and the predicted N-values were compared to SPT N-value of site exploration. From the comparisons it is verified that the exerted electrical energy to bore ground might be used to predict SPT N-value and pile tip location.

• Structural Engineering and Mechanics
• /
• v.58 no.3
• /
• pp.577-596
• /
• 2016

FRP-concrete interfacial mechanical properties determine the strengthening effect of RC beams strengthened with FRP. In this paper, the model experiments were carried out with eight specimens to study the failure modes and the strengthening effect of RC beams strengthened with FRP. Then a theoretical model based on interfacial performances was proposed and interfacial mechanical behaviors were studied. Finite element analysis confirmed the theoretical results. The results showed that RC beams strengthened with FRP had three loading stages and that the FRP strengthening effects were mainly exerted in the Stage III after the yielding of steel bars, including the improvement of the bearing capacity, the decreased ultimate deformation due to the sudden failure of FRP and the improvement of stiffness in this stage. The mechanical formulae of the interfacial shear stress and FRP stress were established and the key influence factors included FRP length, interfacial bond-slip parameter, FRP thickness, etc. According to the theoretical analysis and experimental data, the calculation methods of interfacial shear stress at FRP end and FRP strain at midspan were proposed. When FRP bonding length was shorter, interfacial shear stress at FRP end was larger that led to concrete cover peeling failure. When FRP was longer, FRP reached the ultimate strain and the fracture failure of FRP occurred. The theoretical results were well consistent with the experimental data.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.16 no.1
• /
• pp.18-26
• /
• 2004

In order to accelerate the rate of consolidation settlement, to reduce settlement, and to increase bearing capacity for soft ground under quay, sand compaction pile method (SCP) has usually been applied. SCP-reinforced ground is composite soil which consists of the sand pile and the surrounding soft soil. One of main important considerations in design and analysis for SCP-reinforced soils is stress concentration ratio according to area replacement ratio. In this paper, the numerical analysis was conducted to investigate characteristics of stress concentration ratio in composite ground. It was found that stress concentration ratio of composite ground is not constant as well as depends on several factors such as area replacement ratio, depth of soft soil, and consolidation process. The values of stress concentration ratio increase during loading stage due to stress transfer of composite soil, and reach up to 2.5∼12 according to area replacement ratio at the end of construction. After the end of consolidation, however, these values are converged to 2.5 to 6.0 irrespective of area replacement ratio due to increase in effective stress of soft soil during consolidation process.

• Earthquakes and Structures
• /
• v.24 no.5
• /
• pp.353-364
• /
• 2023

In this study, a method has been proposed for the static and dynamic nonlinear analysis of multi-storey buildings, which takes into account the contribution of axial deformations in vertical load-bearing elements, which are especially important in tall and narrow structures. Shear deformations on the shear walls were also taken into account in the study. The presented method takes into account the effects that are not considered in the fishbone and flexural-shear beam models developed in the literature. In the Fishbone model, only frame systems are modeled. In the flexural shear beam model developed for shear wall systems, shear deformations and axial deformations in the walls are neglected. Unlike the literature, with the model proposed in this study, both shear deformations in the walls and axial deformations in the columns and walls are taken into account. In the proposed model, multi-storey building is represented as a sandwich beam consisting of Timoshenko beams pieced together with a double-hinged beam. At each storey, the total moment capacities of the frame beams and the coupled beams in the coupled shear walls are represented as the equivalent shear capacity. On the other hand, The sums of individual columns and walls moment at the relevant floor level are represented as equivalent moment capacity at that floor level. At the end of the study, examples were solved to show the suitability of the proposed method in this study. The SAP2000 program is employed in analyses. In a conclusion, it is observed that among the solved examples, the proposed sandwich beam model gives good results. As can be seen from these results, it is seen that the presented method, especially in terms of base shear force, gives very close results to the detailed finite element method.