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Experimental investigation of bond–slip behavior of between-anchored steel strips to concrete surface

Kopraman Yağmur, Özdemir Anil, Anil Özgür, Sakin Shaimaa, Armakan Furkan

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 4

art. no. e198, 2022

EN

Reinforced concrete and masonry structures may need strengthening or retrofitting for many different reasons. It is known that strengthening/retrofitting details developed with steel elements are used and widely preferred in these studies. Realistic knowledge of the bond–slip material model between the existing concrete surface and the steel strip in the strengthening/retrofitting details developed using steel strips is extremely important to determine the designed strengthened structural bearing capacity and load–displacement behavior. In the literature review, no study was found in which the bond–slip material model between concrete surfaces and steel strips was investigated extensively. For this reason, an experimental study was planned. In the experimental program, using a special axial tensile test setup designed by the authors, 72 test specimens were tested under the effect of monotonically increased axial tensile force. Axial load displacement, shear stress–shear displacement, and strain distribution values along the steel strip of the test specimens were obtained. It was interpreted how the results were affected by the experimental variables. An innovative bond–slip material model was proposed using the experimental results between the non-anchored and anchored steel strips and the concrete surface. It is thought that the bond–slip model between the developed steel strips and the concrete surface will be useful in the realistic calculation of the bearing capacity and general load–displacement behaviors of the strengthening/retrofitting details designed using steel strips. It can be used in finite element models. It can be used in finite element models. The increase in concrete compressive strength from 10 to 25 MPa increased the axial load maximum bearing capacity values of the steel strips by an average of 44%. The maximum bearing capacity values of the steel strips bonded with a 2 mm thickness epoxy layer were calculated by, on average of 86% higher than the test specimens bonded with 6 mm thickness epoxy. The maximum axial bearing forces of the test specimens in which the axial tensile force was applied concentrically were obtained on an average of 27% greater than the test specimens tested by applying eccentric loading. The maximum bearing capacity values of the test specimens with two anchors on the steel strips adhered to the concrete surface were obtained on an average of 42% higher than the non-anchored test specimens in which only epoxy was used. The maximum bearing capacity values of the test specimens with 400 mm steel strip adhesion length exhibited an average of 108% higher maximum bearing capacity values than the test specimens with 100 mm steel strip bond length.

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Experimental investigation of bonding behavior of anchoraged timber-to-timber joint

Ghoroubi Rahim, Mercimek Ömer, Sakin Shaimaa, Anil Özgür

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e7, 2022

EN

The comprehensive experimental study examining the general load–displacement behavior, stress distributions and shear stress–shear-displacement behaviors in the connection area when wood structural elements are combined with adhesive or adhesive with mechanical anchorages have been found in very limited number of studies in the literature. Therefore, an experimental study was planned. In this study, the general load–displacement behavior of the timber connection regions which are connected by adhesive and mechanical anchorages together with adhesive, with varying lengths of 180, 240 and 350 mm are investigated experimentally. Besides, the effect of changing the number and location of mechanical anchorages used in the connection area on the general load–displacement behavior and shear stress–shear-displacement behavior was also investigated. Using the load–displacement graphs obtained as a result of the experimental study, a generalized material model is proposed for the shear stress–shear-displacement interfacial adhesion surface for wood–wood junction points. This material model, which is proposed for wood–wood connection points with mechanical anchors, is a model that can be useful and can be used in the analysis of structural systems containing such connections using finite element software. It is thought that the overall capacity and load–displacement behavior of structural systems containing such connection points can be calculated more realistically using the proposed interfacial material model.

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Development of a simple bond-slip model for joints monitored with the DIC technique

Biscaia H. C., Franco N., Chastre C.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 4

1535--1546

EN

The monitoring of structures has undergone important advances with the improvements of digital cameras available on the market. Thus, the Digital Image Correlation (DIC) technique has become a viable way of studying engineering problems. Recently it has been used in the debonding failure process between the reinforcement and the substrate. The methods or methodologies that should be followed to obtain the results associated to the debonding phenomenon using the DIC technique need to be better understood and studies on this topic are scarce. The present work therefore proposes a new and inexpensive method to monitor the interfacial behaviour between a reinforcement material and a substrate by combining the use of the DIC technique and a simplified nonlinear bond-slip model. For the validation of the proposed method, a series of single-lap shear tests with a sufficient long bond length carried out by the authors are used. Based on the slip distribution obtained from the DIC technique, it was found that a third-degree polynomial function can be used to approximate the interfacial bond-slip curve of the joint. The validation of the model is made with several analytical solutions using the proposed bond-slip model.