• Computers and Concrete
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• v.17 no.1
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• pp.129-140
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• 2016

Basalt is a type of volcanic rocks, grey to black in colour, contains less than 20% quartz, 10% feldspathoid, and at least 65% of the feldspar of its volume. Basalt is considered an igneous rock with fine grains due to the rapid cooling of lava. Basaltic rocks have been widely used as aggregate for various purposes. The study presented in this paper was carried out on basalts that are widespread in the Madeira Island of Portugal and that comprise the major source of local crushed rock aggregates. This paper discusses an experimental programme that was carried out to study the effects of basaltic aggregate on the compressive strength and modulus of elasticity of concrete. For this purpose, cylinder specimens with $150{\times}300mm$ dimensions and prism specimens with $150{\times}150{\times}375mm$ dimensions were cast. The experimental programme was carried out with several concrete compositions belonging to strength classes C20/25, C25/30, C30/37, C40/50 and C60/75. The Eurocode 2 indicates the modulus of elasticity should be 20% higher when the aggregates are of basaltic origin, however results showed significant differences and a correction is proposed.

• Journal of Industrial Technology
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• v.24 no.A
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• pp.179-184
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• 2004

Each year, new technological advancements for repair-purpose are being introduced to overlay the old deterioration of RC bridge deck at highway by latex-modified concrete. The days may come when this old problem will be successfully resolved. While the experimental works and researches are very active at both laboratory and field, only a few theoretical studies were performed on interfacial problems, especially on stress distribution and concentration of RC beam overlayed by latex-modified concrete. The repaired and strengthened structures would induce a premature failure due to the stress concentration at the adhesive layer of different material before the design expected failure. This paper investigated and proposed an analytical model for predicting interfacial shear and normal stresses of RC beam repair-purpose overlayed by latex-modified concrete. This would be used for predicting interfacial stresses and preventing premature failure at interfaces. This study modified Smith-Teng method for applying to cementitious repairing material, which was based on a direct governing equation and linear-elastic approach for interfacial normal and shear stresses. The proposed theoretical model was verified using commercial FEA program, LUSAS, in terms of interfacial stresses predicted by the proposed model and calculated by LUSAS.

• Computers and Concrete
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• v.3 no.4
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• pp.197-212
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• 2006

Modeling of physically non-linear behavior becomes more and more important for the analysis of SFRC structures in practical applications. From this point of view we will present an effective, three-dimensional constitutive model for SFRC, that is also easy to implement in commercial finite element programs. Additionally, the finite element analysis should only require standard material parameters which can be gained easily from conventional experiments or which are specified in appropriate building codes. Another important point is attaining the material parameters from experimental data. The procedures to determine the material parameters proposed in appropriate codes seem to be only approximations and are unsuitable for precise structural analysis. Therefore a finite element analysis of the test itself is used to get the material parameters. This process is also denoted as inverse analysis. The efficiency of the proposed constitutive model is demonstrated on the basis of numerical examples and their comparison to experimental results. In the framework of material parameter identification the idea of a new, indirect tension testing procedure, the "Modified Tension Test", is adopted and extended to an easy-to-carry-out tension test for steel fiber reinforced concrete specimens.

• International Journal of High-Rise Buildings
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• v.6 no.1
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• pp.33-47
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• 2017

This mixed-use Raffles City (RCH) development is located near the Qiantang River in Hangzhou, the capital of Zhejiang province, located southwest of Shanghai, China. The project incorporates retail, offices, housing, and hotel facilities and marks the site of a cultural landscape within the Quianjiang New Town Area. The project is composed of two 250-meter-tall twisting towers with a form of vibrant waves, along with a commercial podium and three stories of basement car parking. It reaches a height of 60 stories, presenting views both to and from the Qiantang River and West Lake areas, with a total floor area of almost 400,000 square meters. A composite moment frame plus concrete core structural system was adopted for the tower structures. Concrete filled steel tubular (CFT) columns together with steel reinforced concrete (SRC) beams form the outer moment frame of the towers' structure. The internal slabs and floor beams are of reinforced concrete. This paper presents the engineering design and construction of this highly complex project. Through comprehensive discussion and careful elaboration, some conclusions are reached, which serve as a reference guide for the design and construction of similar free-form, hybrid, mix-use buildings.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.683-690
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• 2008

Steel-concrete composite columns are popular for superstructures of bridges, and the outside steel attached to the shaft increases the shaft resistance due to confining concrete. In this study, lateral resistance of steel-concrete composite drilled shafts was evaluated quantitatively based on numerical analysis when steel casings are used as structural elements like composite columns. Ultimate lateral resistance of composite drilled shafts with various diameters was numerically calculated through 3D finite element analysis. For that, elasto-plastic model with perfectly plasticity is involved to capture the ultimate load. A commercial FEM program, MIDAS-GTS, is used in this study. Real field conditions of the West Coast, Korea were considered to set up the ground conditions and pile lengths required for this parametric studies. Detailed characteristics of the stress and displacement distributions are evaluated for better understanding the mechanisms of the composite shaft behavior.

• Nuclear Engineering and Technology
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• v.36 no.6
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• pp.512-527
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• 2004

This paper describes the finite element (FE) analysis results of a 1/4 scale model of a prestressed concrete containment vessel (PCCV) by considering the tension stiffening effect, which is a result of the bond effect between the concrete and the steel. The tension stiffening model is assumed to be an exponential form based on the relationship between the average stress and the average strain of the concrete. The objective of the present FE analysis is to evaluate the ultimate internal pressure capacity of the PCCV, as well as its failure mechanism, when the PCCV model is subjected to a monotonous internal pressure beyond is design pressure capacity. With the commercial code ABAQUS, the FE analysis used two concrete failure criteria: a 2-dimensional axi-symmetric model with modified Drucker-Prager failure criteria and a 3-dimensional model with a damaged plasticity mod디. The results of our FE analysis on the ultimate pressure capacity and failure modes of PCCV have a good agreement with the experimental data.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.105-110
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• 2018

A concrete docking hose of pump car's boom pipe line have been used in many construction sites. They are long structures with continuous cornering, similar to a trunk of the elephant, characterized by a very high pressure resistance of 20MPa. They need flexible materials and structure in order to move the hose smoothy. But commercial concrete hose is hard to handle and heavy owing to adaption of steel reinforcement. In this study, it is tried an experimental approach to the characteristic of inner rubber layer and abrasion resistance. Also, we are investigated the bursting pressure according to the reinforcement of the hose and propose the usefulness of the hose reinforced with high strengthened aramid fiber.

• Journal of the Society of Disaster Information
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• v.14 no.4
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• pp.492-500
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• 2018

Purpose: In this paper, based on this background, the main purpose of studying the behavior of concrete slab reinforced with new material fiber in impact loading is investigated by AFRP using aluminum fiber. Results: Research on the use of new materials as reinforcing materials for concrete members has been carried out in many fields such as flexural and shear tests under static loading, fatigue loading under cyclic loading, and application to PC beams. However, And the issue of plate elements is still at a basic stage. Conclusion: In this paper, the dynamic behavior of reinforced concrete slabs is investigated by using AFRP rod reinforced with aluminum fiber.

• Structural Engineering and Mechanics
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• v.77 no.5
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• pp.673-689
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• 2021

This paper addresses the efficiency of thermal insulation layers applied to protect structural elements strengthened by fiber-reinforced polymers (FRP) in the case of fire event. The paper presents numerical modeling and nonlinear analysis of reinforced concrete (RC) columns externally strengthened by FRP and protected by thermal insulation layers when subjected to elevated temperature specified by standard fire tests, in order to predict their residual capacity and fire endurance. The adopted numerical approach uses commercial software includes heat transfer, variation of thermal and mechanical properties of concrete, steel reinforcement, FRP and insulation material with elevated temperature. The numerical results show good agreement with published results of full-scale fire tests. A parametric study was conducted to investigate the influence of several variables on the structural response and residual capacity of insulated FRP-confined columns loaded by service loads when exposed to fire. The residual capacity of FRP-confined RC column was affected by concrete grade and insulation material and was shown to improve substantially by increasing the concrete cover and insulation layer thickness. By increasing the VG insulation layer thickness 15, 32, 44, 57 mm, the loss in column capacity after 5 hours of fire was 30%, 13%, 7% and 5%, respectively. The obtained results demonstrate the validity of the presented approach for estimation of fire endurance and residual strength, as an alternative for fire testing, and for design of fire protection layers for FRP-confined RC columns.

• Journal of the Korean Society of Safety
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• v.37 no.4
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• pp.101-112
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• 2022

Expanding urbanization practices result in high numbers of buildings being developed in city centers. This high building concentration leads to an increased fire risk, resulting in higher casualty rates and increased economic damages compared to fires in the past. The purpose of this study was to analyze the structural behavior of fire-damaged reinforced concrete buildings using analytical methods and to suggest methods of improving fire resistance in the event of a fire. Damage levels were measured using commercial software to apply the finite element method, ABAQUS, and MIDAS GEN to the dataset. Load-deflection curves were calculated using the effective area and moment of inertia of the fire-damaged columns provided by ABAQUS. The results of this analysis indicate that fire-damaged beams with experience greater deflection from indoor fires than they will from outdoor fires. Fires that occurred on the middle floors were more dangerous than those occurring on higher floors, and eccentrically loaded columns experienced more damage than axially loaded columns. The results indicate that these methods accurately predict structural behaviors of fire damaged concrete columns by considering fire exposure area and eccentric loading.