Column Reinforcement Research Articles

Theoretical Analysis and Finite Element Simulation of the Flat Compressive Stiffness of Oblique Column Reinforced Foam Sandwich Composites

In this paper, the finite element analysis of Ansys software and theoretical analysis was used to study the variation of the flat compression stiffness of the oblique column reinforced sandwich structure with the inclination of the rod and the radius of the rod. The results showed that the inclination angle of the rod increased from 45°. At 90°, the equivalent flat modulus increases by 2 times. When the tilt angle increases from 45° to 70°, as the angle increases, the equivalent flat modulus increases and the rate of change also increases, when the angle of inclination increases. When the angle is greater than 70°, the angle continues to increase, and the rate of change of the equivalent flat compressive modulus gradually becomes slower. The increase in the slanting column radius increases the flat compressive modulus, but increases the upper limit, and at the same time, the increase in radius causes an increase in mass, resulting in a decrease in the specific rigidity. The functional equivalent relationship between the modulus of elasticity and the structural parameters was deduced using the theory of mechanical equivalence. The functional relationship was used to predict the modulus of elasticity. The predicted results were in good agreement with the results of the finite element simulation. The configuration parameter selection provides reference guidance, and the functional relationship can also easily predict the influence of other structural parameters on the Z-stiffness of the sandwich structure.

Reliability analysis of circular reinforced concrete columns subject to sequential vehicular impact and blast loading

This study investigates the first-order second-moment structural reliability of circular reinforced concrete (RC) bridge columns subjected to vehicular impact, explosive blast, and sequential vehicular impact and explosive blast loading. The analysis is performed for five vehicle types of increasing size, mass, and explosive charge capacity. The structural reliability under vehicular impact is shown to be highly sensitive to column diameter, reinforcement ratio, and vehicle velocity. The structural reliability under explosive blast loading is shown to be highly sensitive to column diameter, reinforcement ratio, and blast standoff distance. In general, the structural reliability is lower under explosive blast loading. The structural reliability under sequential loading is evaluated by the newly proposed resistance reduction method and by fault tree analysis. A resistance reduction factor for the second event is defined as a function of the probability of failure under the first event. The resistance reduction method is shown to be more conservative than fault tree analysis and has the added benefit of allowing for the derivation of the density function for performance under sequential loading.

Active and passive protection of steel reinforcement in concrete column using carbon fibre reinforced polymer against corrosion

This study aims to investigate the efficiency of active and passive protection of the pre-corroded steel reinforcement in reinforced concrete (RC) columns using an externally bonded carbon fibre reinforced polymer (CFRP) wrap. Active protection is a novel technique used to impede corrosion achieved by employing the CFRP wrap as the anode of the impressed current cathodic protection (ICCP). Passive protection denotes the anti-corrosion behaviour of the CFRP fabric. Nine reinforced concrete columns with different degrees of corrosion (theoretical mass losses of 1%, 3%, and 6%) were prepared and then treated with different protection methods (non-protection, passive protection, and active protection) by exposing them to wet–dry cycles. By measuring the steel potential, linear polarization, and electrochemical impedance spectroscopy (EIS) of all investigated specimens, the efficiency of active protection was found to be closely related to the degree of the pre-corrosion of the protected specimens. Furthermore, the efficiency of active protection decreased with time, which may be attributed to the deterioration of the CFRP anode and CFRP/concrete interface. Passive protection was proven to be effective in every case, however, it can only slow down the corrosion process but cannot stop the elicited corrosion response.

Innovation of Iron Reinforcing Column of Partical From Frame of Light Steel

Almost half of houses in Indonesia are using lightweight steel roof truss today. The phenomenon in the field is that lightweight steel roof truss can blend with mortar mixture. Thus this phenomenon is captured for later applied dynamically, creatively, and innovatively with new idioms such as reinforcement for columns. This research aims to investigate the comparison of the way of making and the price of the materials between the column material made of the light steel and the column material made of the iron reinforcement which is the most efficient. Type of research is qualitative with a comparative causal approach. This research is divided into several stages, namely; Literature study, column creation, and validation. This study concluds that the manufacture of column material from reinforcement is more efficient, than the lightweight steel column material. The reinforcement column material is more efficient because of the more effective way of making and the price of the working materials more economical than the lightweight steel column material. Lightweight steel columns can be used for public housing on condition made by experienced craftsmen to make the process faster, and the dimensions of lightweight steel can be scaled down to make it more economical.

Ductile Compressive Failure of Concrete Reinforced with High Strength Carbon Hybrid Composite

Background:For centuries, steel rebar has been the primary reinforcement in concrete despite its major drawbacks, such as its heavy weight, high electrical conductivity, and corrosiveness. Thus, in response to the need for better alternatives, innovative Hybrid Composite (HC) reinforcements have been developed.Objective:The focus of this paper is to investigate the performance of tubular HC reinforcements in concrete columns under axial compressive loading.Method:Concrete columns of different sizes were tested.Results and Conclusion:For the small columns, HC reinforced columns showed very high load capacity, which was more than 3 times the capacity of plain concrete. Moreover, significant ductility was achieved with an ultimate strain of up to 59%. For the large columns, HC reinforced columns showed similar load capacities, but much larger ultimate strains in comparison to the corresponding steel reinforced concrete columns.

Steel-reinforced concrete-filled steel tubular columns under axial and lateral cyclic loading

SRCFT columns are formed by inserting a steel section into a concrete-filled steel tube. These types of columns are named steel-reinforced concrete-filled steel tubular (SRCFT) columns. The current study aims at investigating the various types of reinforcing steel section to improve the strength and hysteresis behavior of SRCFT columns under axial and lateral cyclic loading. To attain this objective, a numerical study has been conducted on a series of composite columns. First, FEM procedure has been verified by the use of available experimental studies. Next, eight composite columns having different types of cross sections were analyzed. For comparison purpose, the base model was a CFT column used as a benchmark specimen. Nevertheless, the other specimens were SRCFT types. The results indicate that reinforcement of a CFT column through this method leads to enhancement in load-carrying capacity, enhancement in lateral drift ratio, ductility, preventing of local buckling in steel shell, and enhancement in energy absorption capacity. Under cyclic displacement history, it was observed that the use of cross-shaped reinforcing steel section causes a higher level of energy dissipation and the moment of inertia of the reinforcing steel sections was found to be the most significant parameter affecting the hysteresis behavior of SRCFT columns.

Investigating relationships between cost and CO2 emissions in reinforced concrete structures using a BIM-based design optimisation approach

An integrated design approach for the cost and embodied carbon optimisation of reinforced concrete structures is presented in this paper to inform early design decisions. A BIM-based optimisation approach that utilises Finite Element Modelling (FEM) and a multi-objective genetic algorithm with constructability constraints is established for that purpose. A multilevel engineering analysis model is developed to perform structural layout optimisation, slab and columns sizing optimisation, and slab and columns reinforcement optimisation. The overall approach is validated using real buildings and the relationships between cost and carbon optimum solutions are explored. The study exhibits how cost effective and carbon efficient solutions could be obtained without compromising the feasibility of the optimised designs. Results demonstrate that the structural layout and the slab thickness are amongst the most important design optimisation parameters. Finally, the overall analysis suggests that the building form can influence the relationships between cost and carbon for the different structural components.

Research Summary on the Masonry Structure Reinforcement Technology in China

Based on the analysis of masonry structure seismic characteristics, summary the influence of setting structural column reinforcement technology, steel mesh cement mortar surface strengthening method, carbon fiber sheet reinforcement technology and ECC surface layer reinforcement technology on such performance parameters as bearing capacity, rigidity, ductility, integrity and deformation capacity and the improvement on the seismic performance of masonry structures are summarized. Through the contrast of the advantages and disadvantages of each reinforcement technology, and the combination of research methods and research content, existing problems and non-involved aspects in the masonry reinforcement research area are pointed out, which can provide references for further research on the performance of masonry structure, strengthening and repairing of masonry structures.

Exterior RC Wide Beam–Column Connections: Effect of Spandrel Beam on Seismic Behavior

AbstractThis paper presents the results of a set of experiments performed on four large-scale exterior wide beam–column connections. The beam and column geometry and reinforcement detailing are ide...

Сравнительный анализ параметров армирования колонн монолитных железобетонных безригельных каркасных зданий класса КС-3 при расчете на статические и сейсмические назгрузки

Сравнительный анализ параметров армирования колонн монолитных железобетонных безригельных каркасных зданий класса КС-3 при расчете на статические и сейсмические назгрузки

Numerical study on effect of integrity reinforcement on punching shear of flat plate

Reinforced concrete flat plates consist of slabs supported directly on columns. The absence of beams makes these systems attractive due to advantages such as economical formwork, shorter construction time, less total building height with more clear space and architectural flexibility. Punching shear failure is usually the governing failure mode of flat plate structures. Punching failure is brittle in nature which induces more vulnerability to this type of structure. To analyze the flat plate behavior under punching shear, twelve finite element models of flat plate on a column with different parameters have been developed and verified with experimental results. The maximum range of variation of punching stress, obtained numerically, is within 10% of the experimental results. Additional finite element models have been developed to analyze the influence of integrity reinforcement, clear cover and column reinforcement. Variation of clear cover influences the punching capacity of flat plate. Proposed finite element model can be a substitute to mechanical model to understand the influence of clear cover. Variation of slab thickness along with column reinforcement has noteworthy impact on punching capacity. From the study it has been noted that integrity reinforcement can increase the punching capacity as much as 19 percent in terms of force and 101 percent in terms of deformation.

Punching of reinforced concrete flat slabs with holes and shear reinforcement

Abstract Punching shear is a possible type of failure that occurs in reinforced concrete flat slabs, which can develop with an ultimate load below flexural capacity. Several researchers have studied the punching resistance of flat slabs over recent years. Although they have made great advances, there are codes that show different approaches to a singular design. Some codes show that there exist contradictions, even in the simplest situations, such as concentric loads. Most codes prescribe empirical expressions based in a theoretical model to analyze punching strength, but for flat slabs with holes around the column and shear reinforcement there are divergences between codes, justifying research in this area. This paper presents an experimental analysis of nine square reinforced concrete flat slabs under concentric loading (width: 1800 mm; thickness: 130 mm). The main variables used in the tests were: a) two square openings (150 mm) adjacent to the smallest side of the column and b) the use of shear reinforcement containing 3 layers, with 6 or 8 elements in each layer and radially distributed around the column. The research concludes that openings adjacent to the column affect punching shear strength, while the correct use of the shear reinforcement can minimize and even compensate this loss.

Bearing Capacity of Group of Stone Columns with Granular Blankets

In this research, the bearing capacity of group of floating stone columns with granular blankets was studied using laboratory tests. To investigate the effect of geosynthetic reinforcement on the bearing capacity of these stone columns, geotextiles and geogrids were used for the reinforcement of the stone columns and blankets, respectively. In this paper, certain large body laboratory tests were performed on stone columns with a diameter of 60 mm and lengths of 200 and 350 mm. The main objective of this research is to evaluate the bearing capacity of group of stone columns with granular blankets, record the stress concentration ratio in the group of stone columns without blankets, and investigate the load ratio parameter. The results indicate that the simultaneous application of group of stone columns and granular blankets significantly increased the ultimate bearing capacity of soft soils. Using geosynthetics for the reinforcement of granular blankets or stone columns improved the efficiency of these granular blankets or stone columns. As length of stone columns increased or stone columns were encased in geotextiles, the stress concentration ratio and stiffness of such stone columns were increased. Increasing the length of the short stone columns is more efficient than reinforcing them. Bulging was decreased in reinforced and unreinforced stone columns that were placed under the granular blanket.

Dificultades en el planteamiento del refuerzo de pilares de hormigón armado

The lack of regulations with regards to strengthening reinforced structures prevents the adoption of a standardised approach to even the simplest building structures. Following the analysis of refurbishment projects, it has been concluded that the common denominator in many reinforced columns was the lack of justification of the calculation of the column reinforcement, or even the load transmission between the existing structure and this new reinforcement. Of special concern were the numerous interventions carried out following the earthquake that took place in Lorca in 2011, where many columns had been severely damaged. Although the strengthening solutions implemented in Lorca were diverse, they all followed a similar pattern presenting design solutions that were rushed and lacked a proper evaluation of their effectiveness.This article focuses on an example of a damaged column on a random building floor and the associated challenge related to the design of a strengthening solution and how this may eventually result in a significantly larger scope than initially envisaged.

Experimental and analytical behavior of short concrete columns reinforced with GFRP bars under eccentric loading

This paper presents experimental and analytical studies on short concrete columns reinforced with glass fiber-reinforced polymer (GFRP) towards characterizing compressive behavior GFRP bars. The experimental program consisted of fourteen 500mm-long specimens with a square cross-section (150×150mm) including nine GFRP reinforced (6#5) and five plain concrete specimens. The specimens were tested under concentric and eccentric compressive load up to failure. Three eccentricity to width ratios of 0.1, 0.2, and 0.3 were considered, where the eccentricities applied symmetrically at both ends of simply supported columns. The experimental program showed no crushing of GFRP bars at peak load and the corresponding strain did not reach 50% of their crushing capacity obtained from material test. In addition, an analytical model was developed and verified against the experimental test data. The model considered both material nonlinearity and geometrical nonlinearity. Using the model, a parametric study was performed on the effect of eccentricity, reinforcement ratio, and concrete strength, which confirmed the capability of GFRP bars to sustain high strains without reaching the compressive strain capacity of the bars. The study showed that GFRP bars can be considered as load bearing longitudinal reinforcement of concrete columns and ignoring their effect is not necessary.

Condition Assessment of the Deteriorated Reinforced Concrete Bridge

A comprehensive assessment was conducted to an old reinforced concrete bridge in Brunei Darussalam. This bridge is about 30-40 years old, and has already shown signs of concrete distresses. The main concern was the integrity of the columns, beams and deck, as signs of concrete deteriorations were readily noticeable, e.g. cracks, delaminations, exposed rebar, and concrete spalling. Both visual inspection and non-destructive tests were performed on site. For more detail evaluation, concrete core samples were extracted and sent for testing. Based on information gathered during the investigation and the results of laboratory testing, the reviewed concrete columns were found in bad condition and required immediate repair. The main cause of this concrete distress was the reinforcement corrosion. The vertical column reinforcements were badly corroded and could not function as designed. Without initiating a repair program, it should be prepared for progressive deteriorating conditions, eventually leading to a structural at-risk scenario.

Precast industrial buildings in Southern Europe: loss of support at frictional beam-to-column connections under seismic actions

This paper presents the evaluation of the loss-of-support conditions in frictional beam-to-column connections of industrial precast concrete buildings under seismic actions. This type of connection is widespread throughout Southern Europe in non-seismically designed industrial precast buildings. First, geometric properties of industrial precast buildings and of the frictional beam-to-column connections, together with reference values for the friction coefficient, are reviewed. Then, earthquake time histories taken from the European Strong-Motion sets and recordings of the two major shocks of the 2012 Emilia-Romagna events are presented and discussed showing the importance of the vertical component. Two dynamic models of increasing complexity are used to ascertain loss-of-support conditions under seismic action. The first model is an elastic one, representing a single frame of the industrial buildings. Results are obtained according to: (1) 2D analyses, disregarding the time correlation between the response peaks along the horizontal and vertical directions, (2) 2D analyses taking into account time correlation, and (3) 3D analyses to evaluate also directionality effects. The second model is a 2D non-linear planar frame developed within the OpenSees framework. Results show that simplified (linear) models are a good proxy to more refined (non-linear) ones. However, one must resort to non-linear models if differential displacements between beam and column are of interest. The non-linear numerical investigations show that friction coefficient, horizontal and vertical periods and damping, and column reinforcement ratio are the key variables in estimating the loss-of-support conditions.

Research of electrochemical chloride extraction and reinforcement of concrete column using MPC-bonded carbon fiber reinforced plastic sheet & mesh

Magnesium phosphate cement (MPC) is used as an adhesive that bonds carbon fiber reinforced plastic sheet (CFRP sheet-Cs) and mesh (CFRP mesh-Cm) in formation of the MPC-CFRP composite material. This type of MPC-CFRP composite material can serve as both an anode, Cs and Cm electrodes, for extracting chloride ions and a reinforcement material for concrete columns, and it contributes to bearing capacity improvement and electrochemical chloride extraction (ECE) of concrete structures. Compared with the traditional Ti-RuO2 anode (T electrode), the MPC-CFRP composite material is used to strengthen concrete columns and extract chloride ions. Current density, i=4, 8A/m2, and power-on time, t=14, 28, 42d, are considered to illuminate the effect of the ECE system on the axial compressive strength, chloride ion concentration and bond strength of the rebar-concrete interface of concrete columns. Cs and Cm electrodes can be used as anodes of the ECE system to migrate chloride ions near the rebar effectively toward the concrete surface. The increase of power-on time and current density improves the chloride extraction efficiency. Cs electrode has similar chloride extraction efficiency as T electrode under the same experimental condition superior to Cm electrode. The bond strength of the rebar-concrete interface degrades after ECE and the degradation increases as the current density and power-on time increases. Cs and Cm electrodes significantly improves the bearing capacity and ultimate displacement of concrete columns. However, the strengthening effect decreases as the current density and power-on time increases. The mechanical properties of the strengthened concrete columns are still superior than those of the un-strengthened. Cs and Cm electrodes can achieve the dual effects of reinforcing and repairing reinforced concrete structures. The estimated equations of ECE efficiency and ultimate load of concrete columns agree with the test data.

Effect of Column Size and Reinforcement Ratio on Shear Strength of Glass Fiber-Reinforced Polymer Reinforced Concrete Two-Way Slabs

Effect of Column Size and Reinforcement Ratio on Shear Strength of Glass Fiber-Reinforced Polymer Reinforced Concrete Two-Way Slabs

Finite Element Analysis of Square RC Columns Confined by Different Configurations of Transverse Reinforcement

Introduction:Square reinforced concrete (RC) columns with the confinement effect of transverse reinforcement perform well in ductility and have been used widely in RC structures. Its behavior is the classic topic of anti-seismic and anti-collapse analysis of RC structures. With the advancement of the finite element (FE) analysis technology, the general-purpose simulation tools such as ABAQUS and ANSYS have been universally used to analyze the behavior of structures and members, where the material constitutive model is a key problem in the analysis.Methods:In this study, a new uniaxial compressive stress-strain curve of the confined concrete considering confinement effect of transverse reinforcement in square RC columns was proposed for the concrete damaged plasticity model in ABAQUS to solve the problem that there is no proper uniaxial compressive stress-strain curve for the concrete damaged plasticity model to describe the behavior of concrete confined by transverse reinforcement. Based on the proposed stress-strain relationship, a FE model was developed to analyze the behaviour of laterally confined RC columns under concentric loading.Results:The finite element model is able to predict the response of the confined RC columns from different experiments with reasonable accuracy. Finally, a parametric study was conducted in order to evaluate the effect of confinement reinforcement configuration on the behavior of core concrete in square section.