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Concrete-filled steel hollow (CFHS) column is an innovation to improve the performance of concrete or steel column. It is believed to have high compressive strength, good plasticity and is excellent for seismic and fire performance as compared to hollow steel column without a filler.

Experimental and numerical investigation has been carried out to study the performance of CFHS having different concrete in-fill and shape of steel tube.

In this paper, an extensive review of experiment performed on CFHS columns at elevated temperature is presented in different types of concrete as filling material. There are three different types of concrete filling used by the researchers, such as normal concrete (NC), reinforced concrete and pozzolanic-fly ash concrete (FC). A number of studies have conducted experimental investigation on the performance of NC casted using recycled aggregate at elevated temperature. The research gap and the recommendations are also proposed. This review will provide basic information on an innovation on steel column by application of in-filled materials.

Design guideline is not considered in this paper.

Fire resistance is an important issue in the structural fire design. This can be a guideline to define the performance of the CFHS with different type of concrete filler at various exposures.

Utilization of waste fly ash reduces usage of conventional cement (ordinary Portland cement) in concrete production and enhances its performance at elevated temperature. The new innovation in CFHS columns with FC can reduce the cost of concrete production and at the same time mitigate the environmental issue caused by waste material by minimizing the disposal area.

Review on the different types of concrete filler in the CFHS column. The research gap and the recommendations are also proposed.

Concrete-filled double skin steel tubes (CFDST) columns are taken more attention due to their ability to withstand high structural loads in structures such as high-rise buildings, bridges' piers, offshore and marine structures. This paper is intended to improve the CFDST column's capacity without the need to increase the column's size to maintain its lightweight by filling it with self-compacted concrete (SCC) containing nanoclay (NC).

First, experimental investigation is conducted to select the optimal NC percentage that improves the mechanical properties. Different mixing method, mixture ingredients, cement content, and NC percentage are considered. Then, slender and short CFDST columns are tested for axial capacity to investigate the effect of adding the optimum NC percentage on column's capacity and failure mode.

The test results show that adding 3% NC by cement weight using dry mixing method to SCC is the optimum ratio. It is concluded that adding 3% NC by cement weight increased the CFDST column's capacity, especially the specimens with higher slenderness ratio. Moreover, it is concluded that more specimens should be tested under various geometric and reinforcement details.

Recently, CFDST tube columns solve many structural and architectural problems that engineers have encountered in traditional systems. Therefore, more studies are required to design high-performance columns capable of carrying complex loads with high efficiency since the traditional design could not achieve the required performance. Since concrete contributes to a large portion in the axial capacity of the CFDST columns, it is proposed to improve the CFDST column's capacity without the need to increase the column's size to maintain its lightweight by filling it with (SCC containing NC. Previous research has affirmed the effectiveness of employing nanoclay in the concrete's workability, durability, microstructures, and mechanical properties.

The purpose of this study is to improve the lateral capacity of Cold-Formed Steel (CFS) frame walls filled with lightweight foamed concrete (LFC) and supported with straw boards by introducing structural foamed concrete and/or bracing.

Finite element models are developed and calibrated based on previous experimental work. Then, these models are extended to conduct a parametric study to quantify the effect of filling CFS walls and structural LFC and the effect of supporting CFS walls with bracing.

Results of the study conclude that the finite element analysis can be used to simulate and analyze the lateral capacity of CFS walls effectively since the maximum deviation between calibrated and experimental results is 10%. The structural LFC usage in CFS walls improves the lateral capacity considerably by (25–75) % depending on the wall properties. Besides, the application of lateral bracing does not always have a positive effect on the lateral performance of these walls.

Although CFS walls are preferred due to it is light in weight, low in cost, easy to install and recyclable, low seismic performance, buckling vulnerability, poor thermal insulation and sound insulation properties, low lateral stiffness, and low shear strength limit their use. This study proposes the use of structural foamed concrete and a different bracing method than what is available in the literature. This can overcome the drawbacks of the CFS walls alone which can permit the usage of such walls in mid-rise buildings and other applications.

Nowadays, circular concrete-filled tubular (CFT) columns are largely used in construction because of structural and architectural advantages such as high load bearing capacity and aesthetic appearance. The behavior of CFT columns at ambient and high temperatures is good; however, there are problems related to their behavior in fire when inserted in a real building structure, as for example, the influence of the restraining to thermal elongation that have to be addressed in order to improve their design. This study aims to present the results of a numerical study on the behavior of CFT columns with restrained thermal elongation in case of fire.

The parameters tested in the numerical simulations included column slenderness, load level, surrounding structure stiffness and steel reinforcement ratio. A sequentially coupled thermal stress analysis was carried out. The numerical model was validated with results from a large series of fire resistance tests carried out at Coimbra University, in Portugal. From these, simple equations to evaluate CFT column critical times were derived.

The results were also compared with the ones obtained from the current EN 1994-1-2:2005 simplified calculation and tabulated data methods. For the analyzed cases, it was verified that, while the simplified calculation method led to safe results on the evaluation of the fire resistance of CFT columns with restrained thermal elongation, the tabulated data method led, in certain cases, to unsafe results. This research showed also lower critical times than those from literature on similar type of columns.

The influence of the stiffness of the surrounding structure on the behavior of CFT columns subjected to fire was not yet clear in the major part of the studies already carried out. So, this paper has the originality to consider this parameter in the numerical simulations of this type of columns.

The purpose of this study is to gain a deeper understanding of the structural behaviour of fire-exposed unbraced composite frames. Designers to date paid little attention to unbraced one-bay composite frames as structural system. There are two main reasons for this. First, codes lack simplified methods for the fire design of these frames due to their sway and the linked P-Δ effects when subjected to fire, which complicates the design. Second, it is demanding to construct external composite joints for the regarded one-bay frames. Thus, external joints in composite constructions are mostly constructed as steel joints. Nevertheless, these frames offer advantages. These include increased usable space and flexibility in the building’s use, large spans, fast construction times and inherent fire resistance.

To profit from these benefits, two different external semi-rigid composite joint were developed for the considered one-bay composite frames. The first solution based on concrete-filled steel tube columns and the second on concrete-filled double skin tube columns. Furthermore, a numerical model was established to study the fire performance of unbraced composite frames. The model was validated against four fire tests on isolated composite joints and two large-scale fire tests on unbraced composite frames.

Overall, the predictions of the numerical model were in good agreement with the test results. Thus, the numerical model is appropriate for further investigations on the fire performance of unbraced composite frames.

The sequence of construction results in significant stresses in the steel section, which creates difficulties in numerical modelling and may account for the relatively few studies carried out at room temperature. For the fire design, there was, to the best knowledge of the author, to date no numerical model available that was capable of considering the sequence of construction.

The objective of this research is to evaluate the influence of mineral additions on the mechanical performances of polymer concrete. This study aims to propose a novel approach formulation of polymer concrete based on reduction in the quantity of the binder and disposal of large quantities of industrial by-products and household waste such as the marble, the brick and silica fume whose valuation in polymer concrete could be an interesting ecological and economical alternative. The incorporation of a rate of 10% brick powder affects the distribution of pores inside polymer concrete, that is, the pore diameters become thinner and decrease and the porosity becomes evenly distributed. The recycled mineral brick powder addition in polymer concrete mix improved the mechanical properties.

This polymer concrete was prepared by using polyester resin and two different types of sand, following a new formulation based on an empirical method. Furthermore, the optimal binder percentage was of 20% resin and a mixture of 52% dune sand and 48% quarry sand according to the Abrams method. To achieve our objective, five rates (from 2% to 10%) of brick powder, marble powder and silica fume were examined. Afterwards, its mechanical characteristics were evaluated via a three-point flexural with compressive resistance. The findings indicated that the addition of brick, marble and silica fume to polymer concrete increases the flexural strength with 21.84%, 12.76% and 9.07%, respectively.

Concerning the compressive strength, the best resistance is that of polymer concretes based on brick powder, and this economic formulation of polymer concrete serves the optimal cost/resistance ratio criteria. It allows an improvement in the mechanical resistance of concrete are obtained by adding brick powder that exceed that of the reference concrete.

In the past few decades, there has been several contribution concerning the subject of the reduction of the binder quantity in polymer concretes and adding the industrial and household wastes. However, previous studies revolving around the same area disregarded the effect of the brick powder, which appears scientifically of great importance for enriching the literature.

This paper is aimed at clarifying the behaviour of concrete-filled stainless steel tube (CFSST) slender columns. Based on the review of previous works, it can be found that the pieces of research on the behaviour of CFSST slender columns are very rare and the existing studies, to the author’s knowledge, have not covered this topic in greater depth. The purpose of this paper is to investigate the structural response and strength capacity of eccentric loaded long CFSST columns.

In this paper, a new finite element (FE) model is presented for predicting the nonlinear behaviour of CFSST slender columns under eccentric load. The FE model developed accounts for confinement influences of the concrete in-filled material. In addition, the initial local and overall geometric imperfections were introduced in the numerical model in addition to the inelastic response of stainless steel. The interaction between the stainless section and concrete in-filled was modelled using contact pair algorithm. The FE model was then verified against an experimental work presented in the literature. The ultimate strengths, axial load–lateral displacement and failure mode of CFSST slender columns predicted by the FE model were validated against corresponding experimental results.

The simulation results show that the improvement in the column strengths (compared to hollow section) is less significant when the composite columns have small width-to-thickness ratio. Finally, comparisons were made between the results obtained from FE simulation and those computed from the Eurocode 4 (EC4). It has been found that the EC4 predictions in most analysed cases are conservative for composite columns analysed under a combination of axial load and uniaxial or biaxial bending. However, the conservatism of the code is reduced with a higher slenderness ratio of the composite columns.

The simulation results throughout this research were compared with the corresponding Eurocode predictions.

This paper provides new findings about the structural behaviour of CFSST columns.

Utilising industrial waste, such as fly ash (FA) and bagasse ash (BA), reduces waste management and increases mechanical strength. Concrete is modified with FA and BA in the cool bonded method of concrete preparation.

The study used to partially replace cement with BA powder at proportions 0, 5, 10, 15, 20 and 25% and coarse aggregates are replaced with FA aggregates made with FA and cement using a cold-bonded technique at proportions 0–25%. FA aggregates were made at 10:90, 15:85, 20:80 and 25:75 proportions of cement and FA. The FA aggregates at the best proportion 15:85 was selected as a coarse aggregate by conducting tests like specific gravity, crushing value, impact value and water absorption tests.

The addition of 30% content decreases porosity by 21% and increases strength significantly at 28 days. Microstructure evolution is carried out to identify material behaviour.

Mechanical and durable properties such as flexural strength, tensile strength, water absorption test, acid and alkaline tests are conducted on M50 grade concrete after 3–28 days of curing.

Durability of concrete can be enhanced by reducing the pore size/volume of pores or by entrapping the pores. This can be achieved by adding concrete admixtures that have particle size finer than cement. In this study, GNP, having particle size much smaller than cement, has been introduced/added to concrete mix to control the pore size in concrete to tape out the contribution of GNP in the durability enhancement of concrete.

Different concrete mixes, at various water–cement ratios and amounts of graphene, have been manufactured to produce concrete containing three different %ages of GNP, i.e. 0%, 0.05% and 0.1%. To demonstrate the effect on durability of the concrete through the addition of GNP, these concrete samples have been subjected to repeated Freeze-Thaw cycles. Followed by testing after 28 days of curing, including weight loss, water absorption and strength, which are directly related to the durability aspect of concrete.

It has been observed that the addition of GNP to concrete mixes reduces the weight loss and pore size distribution and enhances tensile and compressive strength of concrete, thereby increasing the durability of concrete in unfavorable circumstances like freeze-thaw i.e. alternate hot and cold weather conditions.

This investigation presents original piece of experimental work conducted on modified concrete (GNP-based concrete). The aim is to construct the civil infrastructure in deep-cold region with increased life span and better performance.

This study aims on a broad review of Concrete's Rheological Properties. The Concrete is a commonly used engineering material because of its exquisite mechanical interpretation, but the addition of constituent amounts has significant effects on the concrete’s fresh properties. The workability of the concrete mixture is a short-term property, but it is anticipated to affect the concrete’s long-term property.

In this review, the concrete and workability definition; concrete’s rheology models like Bingham model, thixotropy model, H-B model and modified Bingham model; obtained rheological parameters of concrete; the effect of constituent’s rheological properties, which includes cement and aggregates; and the concrete’s rheological properties such as consistency, mobility, compatibility, workability and stability were studied in detail.

Also, this review study has detailed the constituents and concrete’s rheological properties effects. Moreover, it exhibits the relationship between yield stress and plastic viscosity in concrete’s rheological behavior. Hence, several methods have been reviewed, and performance has been noted. In that, the abrasion resistance concrete has attained the maximum compressive strength of 73.6 Mpa; the thixotropy approach has gained the lowest plastic viscosity at 22 Pa.s; and the model coaxial cylinder has recorded the lowest stress rate at 8 Pa.

This paper especially describes the possible strategies to constrain improper prediction of concrete’s rheological properties that make the workability and rheological behavior prediction simpler and more accurate. From this, future guidelines can afford for prediction of concrete rheological behavior by implementing novel enhancing numerical techniques and exploring the finest process to evaluate the workability.