• Structural Engineering and Mechanics
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• v.78 no.3
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• pp.319-332
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• 2021

The wood-concrete composite is an interesting solution in the field of Civil Engineering to create high performance bending elements for bridges, as well as in the building construction for the design of wood concrete floor systems. The authors of this paper has been working for the past few years on the development of the bonding process as applied to wood-concrete composite structures. Contrary to conventional joining connectors, this assembling technique does ensure an almost perfect connection between wood and concrete. This paper presents a careful theoretical investigation into interfacial stresses at the level of the two interfaces in composite wooden beam- reinforced concrete slab strengthened by external bonding of prestressed composite plate under a uniformly distributed load. The model is based on equilibrium and deformations compatibility requirements in all parts of the strengthened composite beam, i.e., the wooden beam, RC slab, the CFRP plate and the adhesive layer. The theoretical predictions are compared with other existing solutions. This research is helpful for the understanding on mechanical behaviour of the interface and design of the CFRP- wooden-concrete hybrid structures.

• Structural Engineering and Mechanics
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• v.77 no.4
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• pp.463-472
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• 2021

Fully rigid floor diaphragm is one of the main assumptions that are widely used in common practices due to its simple application. However, determining the exact degree of diaphragms flexibility cannot be easily accomplished without finite element modeling, which is an expensive and time-consuming procedure. Therefore, it is always possible that apparently rigid diaphragms, based on prescriptive limitations of seismic codes, experience some degrees of flexibility during the earthquakes. Since diaphragm flexibility has more uncertainties in asymmetric-plan structures, this study focuses on errors resulting from probable floor diaphragm flexibility of torsionally restrained structures. The analytical models used in this study were single-story buildings with asymmetric plan and RC shear walls. Although floor system is not considered explicitly, a wide range of considered diaphragm flexibility, from fully rigid to quite flexible, allows the results to be generalizable to a lot of lateral load resisting systems as well as floor systems. It has been shown that in addition to previously known effects of diaphragm flexibility, presence of orthogonal side elements during design procedure with rigid diaphragm assumption and rapid reduction in their absorbed forces can also be an important source to increase errors due to flexibility. Accordingly, from the obtained results the authors suggest designers to consider the possibility of diaphragm flexibility and its adverse effects, especially in torsionally restrained systems in their common designs.

• Advances in concrete construction
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• v.11 no.3
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• pp.239-253
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• 2021

The behavior of concrete containing waste glass as a replacement of cement or aggregate was studied previously in the most of researches, but the present investigation focuses on the recycling of waste glass powder as a substitute for silica fume in high strength concrete (HSC). This endeavor deals with the efficiency of using waste glass powder, as an alternative for silica fume, in the flexural capacity of HSC beam. Thirteen members with dimensions of 0.3 m width, 0.15 m depth and 0.9 m span length were utilized in this work. A comparison study was performed considering HSC members and hybrid beams fabricated by HSC and conventional normal concrete (CC). In addition to the experiments on the influence of glass powder on flexural behavior, numerical analysis was implemented using nonlinear finite element approach to simulate the structural performance of the beams. Same constitutive relationships were selected to model the behavior of HSC with waste glass powder or silica fume to show the matching between the modeling outputs for beams made with these powders. The results showed that the loading capacity and ductility index of the HSC beams with waste glass powder demonstrated enhancing ultimate load and ductility compared with those of HSC specimens with silica fume. The study deduced that the recycled waste glass powder is a good alternative to the pozzolanic powder of silica fume.

• Structural Engineering and Mechanics
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• v.89 no.1
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• pp.93-102
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• 2024

Using negative Poisson's ratio materials, an innovative metallic-yielding damper is introduced for the first time in this study. Through the use of ABAQUS commercial software, a nonlinear finite element analysis is conducted to determine the performance of the proposed system. Mild steel plates with elliptical holes are used for these types of dampers, which dissipate energy through an inelastic deformation of the constitutive material. To assess the capability of the proposed damper, nonlinear quasi-static finite element analyses have been conducted on the damper with a variety of geometric parameters. According to the results, the proposed system is ductile and has a high capacity to dissipate energy. The proposed auxetic damper has a specific energy absorption of 910.8 J/kg and a ductility of 33.6. Therefore, this damper can dissipate a large amount of earthquake input energy without buckling by increasing the buckling load of the brace with its ductile behavior. In addition, it was found that by incorporating auxetic dampers in the steel frame, the frame was made harder, stronger, and ductile and its energy absorption increased by 300%.

• Computers and Concrete
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• v.33 no.2
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• pp.163-173
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• 2024

Fiber-reinforced polymers (FRP) have a proven strength enhancement capability when installed into Reinforced Concrete (RC) beams. The brittle failure of traditional FRP strengthening systems has attracted researchers to develop novel materials with improved strength and ductility properties. One such material is that known as polyethylene terephthalate (PET). This study presents a numerical investigation of the flexural behavior of reinforced concrete beams externally strengthened with PET-FRP systems. This material is distinguished by its large rupture strain, leading to an improvement in the ductility of the strengthened structural members compared to conventional FRPs. A three-dimensional (3-D) finite element (FE) model is developed in this study to predict the load-deflection response of a series of experimentally tested beams published in the literature. The numerical model incorporates constitutive material laws and bond-slip behavior between concrete and the strengthening system. Moreover, the validated model was applied in a parametric study to inspect the effect of concrete compressive strength, PET-FRP sheet length, and reinforcing steel bar diameter on the overall performance of concrete beams externally strengthened with PET-FRP.

• International Journal of Highway Engineering
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• v.10 no.2
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• pp.145-157
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• 2008

Load transfer efficiency (LTE) reflects the structural performance of doweled and undoweled joints of Jointed Concrete Pavement (JCP). A 3-dimensional (3-D) model of JCP was built using ABAQUS software in this study. Three concrete slabs were placed on bonded sublayers composed of a base and subgrade. Spring elements were used to connect the adjacent slabs at joints. Different spring constants were input to the model to simulate different joint stiffness of the concrete pavement. The LTE of the joint increased with an increase of the spring constant. The effects of material properties and geometric shape on the behavior of JCP were analyzed using different elastic modulus and thickness of the slab and base in the modeling. The results showed the elastic modulus of the subgrade affected the behavior of the slab and LTE more than that of the base and the thickness of the slab and base. The effects of a negative temperature gradient on the behavior of the slab and LTE were more than that of positive and zero temperature gradients. Joints with low stiffness were more sensitive to the temperature gradient of the slab.

• Tunnel and Underground Space
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• v.11 no.4
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• pp.344-351
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• 2001

In the tunnelling by blasting, the calculations of charge weight and the estimations of blasting effect have been simply carried out by empirical formulas. Also, it has been rare to consider the impact energy of blasting in numerical analyses. Thus in this study a numerical modeling technique of blasting load is developed and used with the 2 dimensional distinct element method(DEM) to consider the nonlinear behaviour of discontinuous underground structures. TD examine and verify its applicability of the numerical model to actual problems, a blasting of tunnel under an embankment is numerically analysed with DEM. It is examined that the behavior of circumference structures, the displacements of above- and under-ground structures, and the propagation of particle velocities can be known by this numerical analysis. As a result, the blasting load model, proposed by this study, can be applied to actual problems. This model applied with DEM can be used in the examination of structural stability.

• Structural Monitoring and Maintenance
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• v.4 no.1
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• pp.17-31
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• 2017

Since extensometers are used to determine the absolute deformation of foundation and abutments and all results are obtained in reference to the base rod, the accuracy of these results has been constantly a subject of debate. In this regard, locating and installing extensometers outside the range of effect zone is also another challenge. The main purpose of this paper is to investigate and modify extensometers results based on the mentioned issues. For this aim, the concrete RCC Zhaveh dam in Iran was selected as the case study. To study the results of extensometers installed in this dam, first, the 3DEC_DP 5.00 software was applied for numerical modeling. Parameters such as discontinuities, dead load and piezometric pressure in the interface of concrete and rock were considered. Next, using the results obtained from 6 extensometers in foundation and abutments and 4 clinometers in dam body, the numerical model was calibrated through back analysis method. The results indicate that the base rod is moved and is not recommended being used as the base point. In other words, because installation of base anchor outside the range of effect zone is not possible due to the operational and economic considerations, the obtained results are not accurate enough. The results indicate a considerable 2-3 mm displacement of the base rod (location of the base anchor) in reference to the real zero point location, which must be added to the base rod results.

• Structural Engineering and Mechanics
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• v.73 no.5
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• pp.529-542
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• 2020

As limited well-documented experimental data are available for assessing the attributes of different deformation components of flanged walls, few appropriate models have been established for predicting the inelastic responses of flanged walls, especially those of asymmetrical flanged walls. This study presents the experimental results for three large-scale T-shaped reinforced concrete walls and examines the variations in the flexural, shear, and sliding components of deformation with the total deformation over the entire loading process. Based on the observed deformation behavior, a simple model based on moment-curvature analysis is established to estimate flexural deformations, in which the changes in plastic hinge length are considered and the deformations due to strain penetration are modeled individually. Based on the similar gross shapes of the curvature and shear strain distributions over the wall height, a proportional relationship is established between shear displacement and flexural rotation. By integrating the deformations due to flexure, shear, and strain penetration, a new load-deformation analytical model is proposed for flexure-dominant flanged walls. The proposed model provides engineers with a simple, accurate modeling tool appropriate for routine design work that can be applied to flexural walls with arbitrary sections and is capable of determining displacements at any position over the wall height. By further simplifying the analytical model, a simple procedure for estimating the ultimate displacement capacity of flanged walls is proposed, which will be valuable for performance-based seismic designs and seismic capacity evaluations.

• The Journal of the Convergence on Culture Technology
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• v.9 no.4
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• pp.593-599
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• 2023

There is risk of derailment due to various factors such as vehicle-track load imbalance in curved parts, so urban railways install and operate derailing prevent guard rails. The angle-type derailing prevent guard rail is composed of various parts including the guard angle. Even if derailment does not occur, various damages occur in the components, so continuous maintenance is required. Through the damage status analysis, the components of the angle-type derailing prevent guard rail with high damage frequency were classified, and conditions for the occurrence of various damages were investigated. In addition, a numerical analysis using a precise 3D numerical model was performed to analyze the cause of the damage analytically. In order to analytically simulate the derailment situation, the static ultimate load condition was applied, and the actual drawing of the angle-type derailing prevent guard rails, rails, and wheels was used for modeling. By analyzing the results of the damage status investigation and finite element analysis, we tried to investigate the damage of the components.