• Computers and Concrete
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• v.2 no.6
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• pp.455-479
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• 2005

This paper describes a 2D nonlinear finite element analysis (NLFEA) platform that combines heat flow analysis with realistic analysis of cracked reinforced concrete structures. The behavior models included in the structural analysis are mainly based on the Modified Compression Field Theory and the Distributed Stress Field Model. The heat flow analysis takes into account time-varying thermal loads and temperature-dependent material properties. The capability of 2D nonlinear transient thermal analysis is then implemented into a nonlinear finite element analysis program VecTor2(C) for 2D reinforced concrete membranes. Analyses of four numerical examples are performed using VecTor2, and results obtained indicate that the suggested nonlinear finite element analysis procedure is capable of modeling the complete response of a concrete structure to thermal and mechanical loads.

• Structural Engineering and Mechanics
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• v.5 no.6
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• pp.743-754
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• 1997

A three-dimensional constitutive modeling for reinforced concrete is presented for finite element nonlinear analysis of reinforced concrete. The targets of interest to the authors are columns confined by lateral steel hoops, RC thin shells subjected to combined in-plane and out-of-plane actions and massive structures of three-dimensional (3D) extent in shear. The elasto-plastic and continuum fracture law is applied to pre-cracked solid concrete. For post cracking formulation, fixed multi-directional smeared crack model is adopted for RC domains of 3D geometry subjected to monotonic and reversed cyclic actions. The authors propose a new scheme of decomposing stress strain fields into sub-planes on which 2D constitutive laws can be applied. The proposed model for 3D reinforced concrete is experimentally verified in both member and structural levels under cyclic actions.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.541-544
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• 2006

This study was performed to proof expansion effect of the mortar bar due to Alkali-silica Reaction (ASR) by ASTM C 1260 test. Recently, the failure case of cement concrete pavement by ASR was reported in Korea. Cement concrete structures are caused crack by ASR. The service life of cracked cement concrete structures by ASR will be shorted. In this study, crushed the slate rock producted Chungcheongnamdo Boryeong was caused 0.3% expansion at 14 days due to ASR by ASTM C 1260 test. The particular spectrum showed that the ASR gel was analyzed contents included Si, Na, K, and Ca by EDX (electron dispersive X-ray spectrometer). It was verified that the crushed aggregate was caused expansion by ASR in Korea.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.694-701
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• 2022

This paper introduces a study of concrete structures with a broken tire and a flat tire as a complete overhaul. The materials used to make concrete in this study are solid aggregate, cement, sand, flat tire, broken wheel, drinking water, and Ordinary Portland Cement. A total of 6 main compounds were thrown into solid cylinders and replaced by 0% as a controller followed by 5% and 10%. The cylinder pressure test of the concrete is done by applying the same pressure to the cylinders until a failure occurs. The results of the pressure test show that by applying 5% aggregation the pressure decreases. In Crumb wheel joints, the compression force decreases constantly as the percentage change increases. Therefore, the crumb wheel is not recommended for use as a complete replacement due to its compressive church power.

• Computers and Concrete
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• v.33 no.6
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• pp.725-738
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• 2024

This study presents a macro-modeling procedure for nonlinear finite element analysis of reinforced and prestressed concrete panels under blast loading. The analysis procedure treats cracked concrete as an orthotropic material based on a smeared rotating crack model within the context of total-load secant stiffness-based formulation. A direct time integration method compatible with the analysis formulation is adapted to solve the dynamic equation of motion. Considerations are made to account for strain rate effects. The analysis procedure is verified by modeling 14 blast tests from various sources reported in the literature including a blast simulation contest. The analysis results are compared against those obtained from experiments, simplified single-degree-of-freedom (SDOF) methods, and sophisticated hydrocodes. It is demonstrated that the smeared crack macro-modeling approach is a viable alternative analysis procedure that gives more information about the structural behavior than SDOF methods, but does not require detailed micro-modeling and extensive material characterization typically needed with hydrocodes.

• Computers and Concrete
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• v.3 no.1
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• pp.65-77
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• 2006

This study reports the details of the finite element analysis of eleven shear critical partially prestressed concrete T-beams having steel fibers over partial or full depth. Prestressed concrete T-beams having a shear span to depth ratio of 2.65 and 1.59 and failing in the shear have been analyzed using 'ANSYS'. The 'ANSYS' model accounts for the nonlinear phenomenon, such as, bond-slip of longitudinal reinforcements, post-cracking tensile stiffness of the concrete, stress transfer across the cracked blocks of the concrete and load sustenance through the bridging of steel fibers at crack interface. The concrete is modeled using 'SOLID65'-eight-node brick element, which is capable of simulating the cracking and crushing behavior of brittle materials. The reinforcements such as deformed bars, prestressing wires and steel fibers have been modeled discretely using 'LINK8' - 3D spar element. The slip between the reinforcement (rebar, fibers) and the concrete has been modeled using a 'COMBIN39'-non-linear spring element connecting the nodes of the 'LINK8' element representing the reinforcement and nodes of the 'SOLID65' elements representing the concrete. The 'ANSYS' model correctly predicted the diagonal tension failure and shear compression failure of prestressed concrete beams observed in the experiment. The capability of the model to capture the critical crack regions, loads and deflections for various types of shear failures in prestressed concrete beam has been illustrated.

• Journal of Korean Society of Steel Construction
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• v.28 no.1
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• pp.1-12
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• 2016

An experimental study was conducted to evaluate the static shear strength of stirrup-reinforced cast-in anchors. The test parameters considered herein are an existence of front bearing bar and concrete crack. M36 anchor was used with an edge distance of 180mm. HD-10 bars were used for all reinforcing bars and the stirrups were placed with 100mm spacing. The shear resistance increased by 16% when the front bearing bar was installed. Meanwhile, the resistance reduced only 5% in the cracked concrete compared with the uncracked concrete. The test results showed that ACI 318 and ETAG 001 specifications could estimate the shear strength of stirrup-reinforced anchors conservatively and a rational method was proposed. A consideration on the fracture strength of stirrup-reinforced anchor is also given.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.104-111
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• 2013

Deterioration is accelerated due to additional intrusion of chloride ion in crack width in cracked concrete. In this paper, modeling on equivalent diffusion coefficient in cracked concrete is performed for 1-D (Anisotropic) and 2-D (Isotropic) diffusion based on steady state condition. In the previous research, rectangular shape of crack was considered but the shape was modified to wedge shape with torturity. For verification of the proposed model, crack is induced in concrete sample and migration test in steady state is performed for 1-D diffusion. For 2-D diffusion, previous test results are adopted for verification. Through considering wedge shape of crack with torturity, diffusion coefficients in 1-D and 2-D diffusion are reduced, and the more reasonable prediction is obtained. The results from the proposed model with torturity of 0.10~0.15 are shown to be in the best agreement with the test results.

• Journal of the Korea Concrete Institute
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• v.19 no.1
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• pp.57-65
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• 2007

Over the past few decades, considerable numbers of studies on the durability of concrete have been carried out extensively. A lot of improvements have been achieved especially in both measuring techniques as well as modeling of ionic flows. However, the majority of these researches have been performed on sound uncracked concrete, although most of in-situ concrete structures have more or less micro-cracks. It is only recent approach that the attention has shifted towards the influence of cracks and crack width on the penetration of chloride into concrete. The penetration of chlorides into concrete through the cracks can make a significant harmful effect on reinforcement corrosion. On the other hand, a general acceptable crack width of 0.3 mm has been recognized for keeping the serviceability of concrete structures in accordance with a lot of codes. However, there seems to be rare established description to explain the critical crack width in terms of the durability of concrete. To make a bad situation worse, there is little agreement on critical crack width among a few of literatures for this issue. Critical crack width is still controversial problem. Nevertheless, since the critical crack width is important key for healthy assessment of concrete structures exposed to marine environment, it should be established. The objective of this study is to define a critical crack width. The critical crack width in this study is designed for a threshold crack width, which contributes to the first variation of chloride diffusion coefficient in responsive to the existence of cracks. A simple solution is formulated to realize the quantifiable parameter, chloride diffusion coefficient for only cracked zone excluding sound concrete. From the examination on the trend of chloride diffusion coefficient of only cracked zone for various crack widths, a critical crack width is founded out.

• Computers and Concrete
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• v.9 no.2
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• pp.133-151
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• 2012

This paper presents an analytical procedure for the analysis of high strength steel fiber reinforced concrete members considering the cracking effect in the serviceability loading range. Modifications to a previously proposed formula for the effective moment of inertia are presented. Shear deformation effect is also taken into account in the analysis, and the variation of shear stiffness in the cracked regions of members has been considered by reduced shear stiffness model. The effect of steel fibers on the behavior of reinforced concrete members have been investigated by the developed computer program based on the aforementioned procedure. The inclusion of steel fibers into high strength concrete beams and columns enhances the effective moment of inertia and consequently reduces the deflection reinforced concrete members. The contribution of the shear deformation to the total vertical deflection of the beams is found to be lower for beams with fibers than that of beams with no fibers. Verification of the proposed procedure has been confirmed from series of reinforced concrete beam and column tests available in the literature. The analytical procedure can provide an accurate and efficient prediction of deflections of high strength steel fiber reinforced concrete members due to cracking under service loads. This procedure also forms the basis for the three dimensional analysis of frames with steel fiber reinforced concrete members.