In the present research, carbon fiber reinforce polymer (CFRP) Composite with fibers aligned along the column axis was used to strengthen the RC columns. A newly introduced method named as grooving method (GM) was utilized to improve the compressive behavior of longitudinal FRP and postpone the buckling and delamination of longitudinal Composite from concrete substrate. Two techniques of GM, i.e. externally bonded reinforcement on grooves (EBROG, to be pronounced as / ebrΛg /) and externally bonded reinforcement in grooves (EBRIG, to be pronounced as / ebrIg /) was used, as well as EBR method, to strengthen the column specimens. For this purpose, 11 RC column specimens with circular section of 150 mm diameter and height of 500 mm were tested under uniaxial compression. Experimental results showed that using the grooving method in strengthening the column specimen, significantly increased the load carrying capacity of specimens; while the conventional EBR method showed inconsiderable effects on the load capacity. The results demonstrated that utilizing EBROG and EBRIG techniques led to respectively 14.1% and 18.5% increase in the column maximum load. However, the column strengthened with EBR method indicated only 2.6% increase in the load carrying capacity.

The use of Near-surface Mounted (NSM) FRP bars is an efficient strengthening technique to enhance the flexural strength of RC structures. This article is intended to analytically investigate the effectiveness of Glass Fiber Reinforced Polymer (GFRP) bars in combination with GFRP wraps on the flexural capacity of reinforced concrete (RC) columns with Fiber Element Modeling approach. The accuracy and reliability of the proposed fiber-based modeling method is demonstrated by numerical models on seven half-scale experimental RC reference columns under axial and cyclic lateral loads. These reference specimens are comprised of seven half-scale RC columns including two unstrengthened and five strengthened specimens with two GFRP bar reinforcement ratios under three axial load levels. Additionally, eight RC strengthened columns are analytically simulated with four complementary GFRP bar reinforcement ratios under two axial load levels. As the numerical results represent good correlation between the fiber-based modeling approach and the experimental results of the reference RC columns, it is concluded that the numerical simulations explicitly predict a considerable improvement in the flexural strength of the RC columns retrofitted with Glass Fiber Reinforced Polymer bars.

One of the most sensitive decisions a structural designer should consider is choosing the type of consumables in the structure. This decision is in many cases dependent on the type of structure, financial issues also the experience and skill of the designer. The main aim pursued in the design is to obtain highly secure, economical structures. Concrete and steel are materials that are widely used in construction. The benefits of both materials are well known today. The clever combination of these two materials, an effective explosion-proof system, will have the effect of exploding explosions in the Plasco building in Tehran compared to using any of the materials. Lack of efficient performance factors, lack of clear and valid guidelines for the seismic design of such columns, how to model their geometry and material can still be obstacles to using such systems. In this research, according to the objectives of the problem, different parameters should be evaluated, this parameter is the type of column cross-section geometry. The aim is to determine the effect of defined parameters, especially column geometry, on the behavior and seismic capacity of Composite columns )CFST(, achieving high resistivity, especially for columns that, incidentally, increase their loading exponentially with increasing classes. It is found that circular sections of Composite columns )CFST( show better behavior and performance than columns with square geometry and further show that Composite columns )CFST( can be used as a basic solution. Use it to solve challenges between designers and architects.

Lightweight concrete has been used in the construction industry for many years and by the introduction of modern technologies in the construction industry, this type of concrete has been accounted as one of the powerful and reliable materials in the construction industry. The density of lightweight concrete is about 0. 56 that of the ordinary concrete. This type of concrete is commonly used as a flooring material in buildings. Thus there is possibility of its corrosion in different climatic conditions. In the present research, we would investigate the compressive strength and durability of the lightweight concrete in the acid environment, so that by specifying the corrosion rate, one could have a better understanding of the behavior of these concretes. For making the lightweight concrete in the present research use has been made of pumice aggregate in the mix design, and the acid used is 1M sulfuric acid. Also, the effect of adding two types of Nanomaterials i. e., Nano silica and Nano clay on the concrete behavior is assessed. The results have shown that in case of keeping the specimens of lightweight concrete in the acid environment for 90 days, their weight reaches 0. 56 that of the ordinary specimens. The results of the current research have shown that the use of Nano silica and Nano lime per 10 wt% of cement could result in the increased compressive strength of the lightweight concrete. So that the concrete compressive strength per 10 wt% of Nano lime increases by 1. 43%. On the other hand, the concrete durability in the acid solutions reaches the maximum value per addition of 5% Nano silica and 5% Nano lime, and has lost a lower percentage of its weight.

The paper presents the results of a study on the ductility behavior of Composite fibre reinforced polymer- high strength concrete columns under uni-axial compression. The columns had slenderness ratios of 8, 16, 24 and 32. Three types of wrap materials (Chopped Strand Mat GFRP, Uni-Directional Cloth GFRP and Woven Roving GFRP) were used with 3 mm and 5 mm thicknesses. The columns were tested under monotonic axial compressive loading up to failure. The deflections and axial strain were noted for each load increment.The HSC columns with GFRP wrapping exhibited improved performance in terms of deflection ductility and energy ductility capacity. Regression equation has been proposed for predicting the performance parameters. A better correlation has been observed between the test results and those predicted through the proposed equations.