• Structural Engineering and Mechanics
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• v.76 no.1
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• pp.67-81
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• 2020

Pretensioned concrete (PC) is widely used in contemporary construction. Bond of prestressing strand is significant for composite-action between the strand and concrete in the transfer and flexural-bond zones of PC members. This study develops a new methodology for quantifying the bond of 18-mm prestressing strand in PC members based on results of a pullout test, the Standard Test for Strand Bond (STSB). The experimental program includes: (a) twenty-four pretensioned concrete beams, using a wide range of concrete compressive strength; and (b) twelve untensioned pullout specimens. By testing beams, the transfer length, flexural-bond length, and development length were all measured. In the STSB, the pullout forces for the strands were measured. Experimental results indicate a significant relationship between the bond of prestressing strand to the code-established design parameters, such as transfer length and development length. However, the code-predictions can be unconservative for the prestressing strands having a low STSB pullout force. Three simplified bond equations are proposed for the design applications of PC members.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.3 no.4
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• pp.1-10
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• 2000

This study aims at the new design system development of landscape architecture structures, as soundproof wall using reinforced soil block. This structures, that is new soundproof wall system, have to be maintained stability on acting critical wind load, which is combined exist soundproof wall system and soundproof wall system using environmental green stone block. To the harmony of this system, the post block, so-called landscape block or cast block, is manufactured. It's possible to stand of the post bearing system combined with post-pile and post block. Through the comparison with a serious code for the acting wind load on the soundproof wall, the reasonable wind load could be calculated. Also, the mechanical stability on the green stone block was checked by the Lab. tests based on the UBC (Uniformed Building Code). Because the critical height of soundproof wall system using green stone generally was restricted, the new system demands to combination of the exist system and the new system. For the stability analysis of them, the utility program, SAP2000, was used. And, a semi-auto program on the design system of the new soundproof wall using green stone was developed, which can be easily use because of the simplification.

• Computers and Concrete
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• v.15 no.3
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• pp.357-372
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• 2015

This study reports the test results of twelve reinforced concrete deep beams. The deep beams were tested with loads applied through and supported by columns. The main variables studied were the shear span-to-depth ratios, and the horizontal and vertical stirrups. The shear strengths can be effectively enhanced for deep beams reinforced with both horizontal and vertical stirrups. The test results indicate the shear strengths of deep beams increase with the decrease of the shear span-to-depth ratios. The normalized shear strengths of the deep beams did not increase proportionally with an increase in effective depth. An analytical method for predicting the shear strengths of deep beams is proposed in this study. The shear strengths predicted by the proposed method and the strut-and-tie model of the ACI Code are compared with available test results. The comparison shows the proposed method can predict the shear strengths of reinforced concrete deep beams more accurately than the strut-and-tie model of the ACI Code.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.1
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• pp.49-57
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• 2013

Structural elements of typical bridges are superstructure, connections, substuctures and foundations and earthquake resistance is decided with the failure mechanism formed by substuctures and connections. Therefore earthquake resistant design should be carried out in the basic design step where design strengths, e.g. design sections for structural elements are determined. The Earthquake Resistant Design Part of Korean Roadway Bridge Design Code provides two basic design procedures. The first conventional procedure applies the Code-provided response modification factors. The second new procedure is the ductility-based earthquake resistant design, where designer can determine the response modification factors. In this study, basic designs including the two design processes are carried out for a typical bridge and supplements are identified in view of providing earthquake resistance.

• Earthquakes and Structures
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• v.9 no.5
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• pp.1069-1089
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• 2015

This paper investigates the limits and efficacies of the Fiber Reinforced Polymer (FRP) material for strengthening mid-rise RC buildings against seismic actions. Turkey, the region of the highest seismic risk in Europe, is chosen as the case-study country, the building stock of which consists in its vast majority of mid-rise RC residential and/or commercial buildings. Strengthening with traditional methods is usually applied in most projects, as ordinary construction materials and no specialized workmanship are required. However, in cases of tight time constraints, architectural limitations, durability issues or higher demand for ductile performance, FRP material is often opted for since the most recent Turkish Earthquake Code allows engineers to employ this advanced-technology product to overcome issues of inadequate ductility or shear capacity of existing RC buildings. The paper compares strengthening of a characteristically typical mid-rise Turkish RC building by two methods, i.e., traditional column jacketing and FRP strengthening, evaluating their effectiveness with respect to the requirements of the Turkish Earthquake Code. The effect of FRP confinement is explicitly taken into account in the numerical model, unlike the common procedure followed according to which the demand on un-strengthened members is established and then mere section analyses are employed to meet the additional demands.

• Steel and Composite Structures
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• v.7 no.4
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• pp.321-337
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• 2007

The investigation on the behaviour of cold-formed stainless steel non-slender circular hollow section columns is presented in this paper. The normal strength austenitic stainless steel type 304 and the high strength duplex materials (austenitic-ferritic approximately equivalent to EN 1.4462 and UNS S31803) were considered in this study. The finite element method has been used to carry out the investigation. The columns were compressed between fixed ends at different column lengths. The geometric and material nonlinearities have been included in the finite element analysis. The column strengths and failure modes were predicted. An extensive parametric study was carried out to study the effects of normal and high strength materials on cold-formed stainless steel non-slender circular hollow section columns. The column strengths predicted from the finite element analysis were compared with the design strengths calculated using the American Specification, Australian/New Zealand Standard and European Code for cold-formed stainless steel structures. The numerical results showed that the design rules specified in the American, Australian/New Zealand and European specifications are generally unconservative for the cold-formed stainless steel non-slender circular hollow section columns of normal and high strength materials, except for the short columns and some of the high strength stainless steel columns. Therefore, different values of the imperfection factor and limiting slenderness in the European Code design rules were proposed for cold-formed stainless steel non-slender circular hollow section columns.

• Earthquakes and Structures
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• v.18 no.6
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• pp.709-718
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• 2020

Fragility curves are useful tools to estimate the damage probability of buildings owing to seismic actions. The purpose of this study is to investigate seismic vulnerability of reinforced concrete (RC) buildings, according to the 2007 and 2018 Turkish Seismic Codes, using fragility curves. For the numerical analyses, typical five- and seven-storey RC buildings were selected and incremental dynamic analyses (IDA) were performed. To complete the IDAs, eleven earthquake acceleration records multiplied by various scaling factors from 0.2g to 0.8g were used. To predict nonlinearity, a distributed hinge model that involves material and geometric nonlinearity of the structural members was used. Damages to confined concrete and reinforcement bar of structural members were obtained by considering the unit deformation demands of the 2007 Turkish Seismic Code (TSC-2007) and the 2018 Turkey Building Earthquake Code (TBEC-2018). Vulnerability evaluation of these buildings was performed using fragility curves based on the results of incremental dynamic analyses. Fragility curves were generated in terms of damage levels occurring in confined concrete and reinforcement bar of structural members with a lognormal distribution assumption. The fragility curves show that the probability of damage occurring is more according to TBEC-2018 than according to TSC-2007 for selected buildings.

• Geomechanics and Engineering
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• v.22 no.5
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• pp.461-473
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• 2020

Natural rock mass contains defects of different shapes, usually filled with inclusions such as clay or gravel. The presence of inclusions affects the failure characteristics and mechanical properties of rock mass. In this study, the strength and failure characteristics of rock with inclusions were studied using the particle flow code under uniaxial compression. The results show that the presence of inclusions not only improves the mechanical properties of rock with defects but also increases the bearing capacity of rock. Circular inclusion has the most obvious effect on improving model strength. The inclusions affect the stress distribution, development of initial crack, change in crack propagation characteristics, and failure mode of rock. In defect models, concentration area of the maximum tensile stress is generated at the top and bottom of defect, and the maximum compressive stress is distributed on the left and right sides of defect. In filled models, the tensile stress and compressive stress are uniformly distributed. Failing mode of defect models is mainly tensile failure, while that of filled models is mainly shear failure.

• Structural Engineering and Mechanics
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• v.35 no.3
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• pp.265-282
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• 2010

The shear contribution of transverse steel in reinforced concrete beams is generally assumed as independent of the concrete strength by most of the building codes. The shear strength of RC beams with web reinforcement is worked out by adding the individual contributions of concrete and stirrups. In this research 70 beams of medium strength concrete in the range of 52-54 MPa, compressive strength were tested in two sets of 35 beams each. In one set of 35 beams no web reinforcement was used, whereas in second set of 35 beams web reinforcement was used to check the contribution of stirrups. The values have also been compared with the provisions of ACI, Eurocode and Japanese Code building codes. The results of two sets of beams, when compared mutually and provisions of the building codes, showed that the shear strength of beams has been increased with the addition of stirrups for all the beams, but the increase is non uniform and irregular. The comparison of observed values with the provisions of selected codes has shown that EC-02 is relatively less conservative for low values of longitudinal steel, whereas ACI-318 overestimates the shear strength of RC beams at higher values of longitudinal steel. The Japanese code of JSCE has given relatively good results for the beams studied.

• Geomechanics and Engineering
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• v.25 no.2
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• pp.111-121
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• 2021

Large deformation and rapid pressure propagation take place inside the rock mass under the dynamic loads caused by the explosives, on quarry faces in order to extract aggregate material. The complexity of the science of rock blasting is due to a number of factors that affect the phenomenon. However, blasting engineering computations could be facilitated by innovative software algorithms in order to determine the results of the violent explosion, since field experiments are particularly difficult to be conducted. The present research focuses on the design of a Finite Element Analysis (FEA) code, for investigating in detail the behavior of limestone under the blasting effect of Ammonium Nitrate & Fuel Oil (ANFO). Specifically, the manuscript presents the FEA models and the relevant transient analysis results, simulating the blasting process for three types of limestone, ranging from poor to very good quality. The Finite Element code was developed by applying the Jones-Wilkins-Lee (JWL) equation of state to describe the thermodynamic state of ANFO and the pressure dependent Drucker-Prager failure criterion to define the limestone plasticity behavior, under blasting induced, high rate stress. A progressive damage model was also used in order to define the stiffness degradation and destruction of the material. This paper performs a comparative analysis and quantifies the phenomena regarding pressure, stress distribution and energy balance, for three types of limestone. The ultimate goal of this research is to provide an answer for a number of scientific questions, considering various phenomena taking place during the explosion event, using advanced computational tools.