Types Of Cross Sectional Aspect Ratio

As the human body ages, it becomes more fragile. America’s infrastructure is nearly the same. With the everyday use of many large structures, such as bridges, buildings, and other large structures made of concrete and/or steel, many are beginning to wither away while the average American is unaware of these changes. In many projects around the world, there is a material that is being commonly used to strengthen structures known as Carbon Fibre Reinforced Polymer (CFRP). The types of structures that this material can help to strengthen includes, but is not limited to, reinforced concrete columns, bridge girders, steel structures, and cable

Introduction : To determine the strength, maximum load can be applied and workability of concrete mixture.

The use of steel rebars was started in construction in 18th century. Cast iron was used in the earlier age. Cast iron rebars were of high quality, and there was no corrosion. The technique was refined by embedding the steel bars in concrete. Square twisted steel bars (deformed bars) were introduced in 1960s but these were phased out due to their inherent inadequacies. Later the steel rebars of high yield strength were produced by raising carbon (>0.5 and <1.0 wt% content) as well as manganese contents. Carbon was added to steels in order to achieve strength and later on it was realized that higher content of carbon created problem of brittleness and accelerated rate of corrosion (due to the presence of higher proportion of cementite phases

The testing is done in a laboratory off-site. The only work done on-site is to make a concrete cylinder for the compression test. The strength is measured in Megapascals (MPa) and is commonly specified as a characteristic strength of concrete measured at 28 days after mixing. The compressive strength is a measure of the concrete’s ability to resist loads which tend to crush it.

The report primarily discusses results obtained from the conducted experiments and includes computed data from the Kingston computer program. The value of the plastic moment capacity of each experiment was obtained; Obtained value was used to find the yield strength of the structures and compare them to typical values for mild steel. The important data is summarized in a table; followed by a list of important formulae. All individual results are listed in the appendix at the end.

In some cases, lateral force shapes result to good approximation of demand displacements. Nevertheless, there has not been found any constant loading for exact approximation of local mechanisms and plastic hinges. Earthquake codes have made it mandatory to use a minimum of two lateral load patterns in nonlinear static procedure. These two load patterns are chosen to cover resulting forces in actual dynamic response of the structure. There are two load patterns which are used mostly in usual studies: uniform and modal load pattern. When using uniform load pattern, called also constant acceleration pattern, lateral forces applied to the structure are proportional to the mass of the building stories. This load pattern emphasizes on bottom floors demands more than top floor demands. It also increases the importance of shear in stories against overturning moment while modal load pattern emphasizes overturning moment and story demands. The FEMA356 code allows using comparative load pattern instead of constant load pattern. In this method the load pattern varies by plastic hinges as the displacements in the structure increase.

Over the last two decades Fiber Reinforced Polymers have emerged as an attractive competitor to the more conventional civil engineering materials for the creation of new structures and the strengthening/rehabilitation of existing ones [1-book]. Therefore many related associations such as ACI committee provided practical design manuals for all aspects of application FRPs for strengthening structural elements. The comparison between experimental and analytical code based studies performs previously for shear strengthening of RC beam with FRP composites is not very promising. Specially for shear strengthening the use of additional principle in the actual shear design equations must be questioned.[] The large dispersion between the expected values of different models and experimental results is of real concern bearing in mind some of this semi-empirical models are applied to present design codes. [01-arc] Shear strengthening of RC members with FRP is actually a research problem have not been completely solved and is still under investigation; [2-ar] so that the trustworthiness of existing models to achieve reliable and safe codification needs to be evaluated. Many uncertainties and complicated problems have assessed so far for strengthening of RC beams with FRPs are: real effective strain of FRPs in shear strengthening [Chen & Teng 2003a], main failure modes recognized for each section configuration, most accurate evaluation model [03-arc], and interactions between the external

Several analytical models for the non-linear analysis of reinforced concrete structural components have been proposed. These range from very refined and complex finite element models (N go and Scordelis I967) to simplified macro-models (Chen and Powell 1982, Lai et al, 1984, Powell and Campbell 1994, Pctrangeli et al. l999). Refined analytical models are typically used in predicting the response of small structures or structural subassemblies. The use of refined finite element models in non-linear static, cyclic and dynamic response of reinforced concrete frames is complex, time consuming and may not be practical. On the other hand, simplified macro-models have been

However, the number of studies on the axial stress-strain behavior of FRP-confined RC columns subjected to a cyclic axial compression loading has been going up slowly, particularly for noncircular RC columns. A better understanding of the latter and a sufficient summary of laboratory testing results can lead to the development of well-informed and calibrated cyclic uniaxial stress-strain model. In fact , Research is more limited on the cyclic axial stress-strain behavior of FRP-confined rectangular reinforced concrete columns of large scale, unlike several cited articles that previously explored the influence of the cyclic axial loading on the behavior of FRP- confined unreinforced concrete specimens including cylinders and noncircular specimens of small size many researchers tested (e.g., Shao et al. 2006; Lam et al. 2006; Lam and Teng 2009; Abbasnia and Ziaadiny 2010; Abbasnia et al.2012a,b; Abbasnia and Holakoo 2012; Ozbakkaloglu and Akin 2012;Abbasnia et al. 2013; Bai et al. 2013; Harajli et al. 2015).

Introduction: It is widely known that many older reinforced concrete columns may suffer from an inadequate amount of transverse steel reinforcement providing insignificant confining pressure to the concrete core. The seismic performance of these columns may thus be very poor due to their insufficient ductility or low concrete strength. Because the FRP composites owe some of the favorable properties such as high strength-to-weight ratio, the use of FRP composites is nowadays become more common in the construction industry as a confining material for concrete to enhance the strength and ductility capacities of existing RC columns. To achieve a proper and safe design of FRP-confined rectangular RC columns, it is necessary to properly understand and model the axial stress-strain behavior of FRP-confined concrete. The axial cyclic stress-strain behavior of FRP-confined concrete is of particular importance in the seismic design of existing RC columns.

The steel tube in a concrete filled tubular (CFT) column acts as both lateral and longitudinal reinforcement, and is thus subjected to hoop tension and biaxial stresses of longitudinal compression. At the same time, concrete is tri-axially stressed. Concrete filled tubular (CFT) column has become popular as structural-member in buildings due to their excellent performance for structural characteristics, which include high ductility, stiffness, and high strength. The advantages of the Concrete filled tubular (CFT) column over other composite members are that the filled-in concrete prolongs local buckling of the steel tube wall, the steel tube provides formwork for the concrete, the tube prevents excessive concrete spalling and composite columns add more stiffness to a frame compared to old-style steel frame construction. According to past study on the concentric compression behavior of Concrete filled tubular (CFT) columns, the ultimate axial strength of Concrete filled tubular (CFT) columns is largely affected by the thickness of the steel tube and the shape of its cross section Although confining effect in square columns show a small increase in axial strength due to triaxial-effects, although it has large wall thicknesses. On the other hand, the axial load and deformation behavior of columns is remarkably affected by the cross sectional shape, diameter/width-to thickness ratio (D/t) of the steel tube, and the strength of the filled concrete.

For examples, placement of seal concrete, mass concrete and shaft concrete can be successfully placed without vibration. These seal, mass and shaft concretes are generally of lower strength, less than 34.5 MPa and difficult to attain consistent quality. Modern application of self-compacting concrete (SCC) is focused on high performance and more reliable quality, dense and uniform surface texture, improved durability, high strength, and faster construction.

Abstract 1: A slowly growing number of studies have concentrated too much on investigating, but less on modelling the cyclic axial stress-strain response of concrete columns (RC) confined with fiber-reinforced polymer FRP sheets. Since the early 1990s, the largest amount of research, including both experimental and analytical studies, has been rising continuously, in contrast, on the monotonic axial stress-strain behavior of concrete columns externally jacketed with FRP composite wraps. However, most of the available literature on the behavior of FRP-confined RC columns has focused extensively on square and circular concrete columns that can be classified as small or medium-size. Also recently, a few experimental studies have been devoted to investigating the cyclic axial compression behavior of small-scale unreinforced (plain) rectangular concrete columns with smaller-cross sections. Therefore, a deep review indicates that there is a distinct lack of research on the axial stress-strain behavior of FRP-confined RC columns subjected to a cyclic axial compression loading. This is owing to the fact that the majority of the structural buildings columns (RC) are noncircular ,and it has been clearly demonstrated that the behavior of these columns mainly depends on several factors such as aspect ratio of cross-section,

Abstract -The study includes an investigation of the stresses, deflections capacity and lateral-torsional buckling behavior of regular I section steel column of jib crane subjected to a axial compressive eccentric loading. The lateral torsional buckling is the main failure mode that controls the design of “slender” column. Different shapes of columns are proposed in this study with different cross section, web shapes and materials. Finite element analysis and experimental study are carried out on both types (i.e. Regular and proposed column) to calculate and validate results. An optimization technique is used to optimize the solution from proposed different designs. The thickness of the web and thickness of column is constant for all specimens with length 2 to 3 m and tested for 500, 750 and 1000 Kg load lifting capacity. Structural analysis is done to examine the influence of the section dimension due to axial compressive eccentric loading on column. Using the study it is observed that not only the web thickness, but also the shape of web, angle of web and sectional cross section of steel column influences the resistance to lateral torsional buckling and bending.

The maintenance, restoration and development of structural components, is maybe one of the most typical problems in construction field applications. In addition, a huge number of structures developed in the past utilizing the ancient established design codes in various parts of the world are basically structurally hazardous as indicated to the recent time design codes on the other hand the retrofitting has become necessary due to the environmental degradation, heavier loading conditions and their life spans. Therefore, various strengthening techniques are being introduced, historically the structural components were repaired by post-tensioning or jacketing with new concrete in conjunction with a surface adhesive, since mid-1960’s steel