Mohammed Altaee
@uobabylon.edu.iq
University of Babylon
Scopus Publications
Scopus Publications
Majid M. A. Kadhim, Akram Jawdhari, Mohammed M. Altaee, Ali Majdi, and Amir Fam
Elsevier BV
Mohammed J. Altaee, Sarmed A. S. Altayee, Majid M. A. Kadhim, Akram Jawdhari, Ali Majdi, Ali Chabuk, and Nadhir Al-Ansari
Hindawi Limited
Existing bond-slip (τ-s) relations for fibre-reinforced polymer (FRP)-steel joints employ different shapes and mathematical expressions, inferring that their predictions of failure load and mode, and other interface properties, might be inconsistent or inaccurate. In this study, predictions of four widely used τ-s relations are evaluated using a large experimental database of 78 double-lap FRP-steel specimens. To facilitate the evaluation process, a robust finite element (FE) model is developed for each test, implementing data from either of the existing τ-s relations to define the FRP-steel interface. Comparisons between test and FE results indicated that the existing τ-s models were unable of predicting the ultimate load (Pu) and effective bond length (Leff) of FRP-steel joints, or the relation between Pu and bond length and that between Leff and FRP modulus (Ef). A new τ-s model is developed based on an inverse FE simulation, comparison with experimental results, and regression analysis. It considers the effects of Ef, the type of FRP reinforcement (sheet or plate), and applies to both linear and nonlinear adhesives. The model predictions were validated by comparing with results from small bond tests and large FRP-strengthened steel beams tested under bending, yielding excellent results for Pu, failure mode, and all other interfacial properties.
Majid M. A. Kadhim, Mohammed J. Altaee, Ali Hadi Adheem, Ali Chabuk, and Nadhir Al-Ansari
Hindawi Limited
The use of NSM FRP strengthening of concrete structures has become an attractive option to retrofit the existing structures against shear and flexure. This paper reviews only the utilization of NSM for shear in previous review articles. A database of tests of NSM strengthened beams in shear is presented to evaluate the existing design formulations of calculating the NSM contribution in shear. These formulations were in agreement with the experimental results in the database. Further research topics are also identified such as the shape of NSM FRP bars, combined effects of existing steel stirrups, and NSM FRP reinforcement and analytical formulations.
Majid M.A. Kadhim, Akram R. Jawdhari, Mohammed J. Altaee, and Ali Hadi Adheem
Journal of Building Engineering Elsevier BV
Abstract In this study, a non-linear three-dimensional finite element model was developed to study the impact behaviour of reinforced concrete beams strengthened in shear and/or flexure with carbon-FRP (CFRP) sheets. Concrete damage plasticity model was used for the concrete part, a traction-separation law for the CFRP-concrete interface, and Hashin criteria for rupture in CFRP. Comparisons with experimental data from literature, for various properties, confirmed the accuracy of developed model. A detailed parametric analysis was performed focusing on: the impact location as a ratio (α) from support to mid-span, impact velocity (v); and several geometrical properties related to CFRP technique. Increasing α from 0.26 to 0.79 results in increasing the maximum displacement (Δmax) for both un-strengthened and strengthened beams. CFRP strengthening resulted in decreasing Δmax for different values of α and v and prevented global concrete failure for v = 8.86 m/s. Δmax is also decreased by 13% when a round corner and an arched soffit were used to prepare the beam substrate for bonding the transverse sheets instead of a sharp corner. Furthermore, the paper presents detailed discussions and implications for the above parameters and two additional ones, namely: configuration of transverse sheets (continuous wraps or discontinuous strips) and thickness of CFRP longitudinal sheets.
Mohammed Altaee, Lee S. Cunningham, and Martin Gillie
Elsevier BV
Abstract Strengthening of existing steelwork is often necessary where a change of use or geometric modifications are made. In the case of floor beams, it is particularly common to introduce web openings to accommodate services such as air conditioning etc. The use of carbon fibre reinforced polymer composites (CFRP) overcomes several of the difficulties associated with the use of traditional strengthening techniques with welded steel plate. CFRP has a superior strength to weight ratio than steel and has excellent corrosion resistance. In comparison to welded plate, CFRP is generally easier to handle and apply. Currently there is a scarcity of research on the application of CFRP to steel beams with web openings and the work that does exist is limited to relatively small-scale beams. In the present work a numerical model validated against experimental work by the authors is used investigate the application of CFRP to floor beams common in everyday practice. The results show that practical and efficient layouts of CFRP can be used to achieve similar or greater strengthening effect in comparison to traditional steel plate methods.
Mohammed J. Altaee, Lee S. Cunningham, and Martin Gillie
Elsevier BV
Abstract The introduction of web openings in existing steel floor beams is a common occurrence in practice. Such modifications are often necessary to accommodate additional services driven by a change of building use, thus extending the service life of the structure. Depending on their size and location, openings in the web can present a major challenge to the strength and stiffness of the beam. Strengthening around an opening is often necessary to maintain the required performance of the floor beam, traditionally this is affected via application of additional steel plate, either bolted or welded. This paper focusses on the novel application of carbon fibre reinforced polymer (CFRP) to the problem of strengthening web openings, taking advantage of the material's ease of handling, superior strength-to-weight ratio and corrosion resistance. An experimental study involving 4 full scale universal beams was conducted in order to investigate the ability of CFRP to recover the strength and stiffness of beams following the introduction of web openings. All the specimens were tested under 6-point bending in the experiments. For further comparison, the equivalent test series without the addition of strengthening was modelled numerically via finite element analysis.. The effectiveness of the strengthening technique was demonstrated with increases in the load carrying capacity over the un-altered beam of between 5 and 20% being achieved.