Amount Of Steel Reinforcement Research Articles

Numerical analysis of load-bearing capacity of shear-strengthened reinforced concrete beams without shear reinforcement using side-bonded CFRP sheets

As CFRP (carbon fiber-reinforced polymer) offers high retrofit efficiency for structural members in bending and shear due to its superior mechanical properties compared to steel, sheets made from this material have become ubiquitous in strengthening existing reinforced concrete (RC) structures. However, there needs to be more research on RC beams with no stirrups that have been shear-strengthened with side-bonded CFRP sheets. As such, this study aims to investigate this specific topic and assess design-related parameters that impact the load-bearing capacity of these shear-strengthened beams. To achieve this, nonlinear finite element models of four RC beams, including one control beam and three beams strengthened with side-bonded CFRP sheets, were built and verified regarding shear capacity, crack patterns, and failure mechanisms. The simulated beams demonstrated a high level of accuracy in all mentioned aspects. Numerical models were then developed to evaluate the design-oriented parameters that affect the response of shear-strengthened beams, including the concrete compressive strength, the amount of steel reinforcement, the number of CFRP layers, the CFRP bonding configuration, and the shear span-to-effective depth ratio. The results showed that not only the compressive strength of the concrete but also the amount of steel longitudinal reinforcement had a significant relationship with the load-bearing capacity of shear-strengthened beams. Meanwhile, the bonding configuration and the layer number of side-bonded CFRP sheets considerably influenced the ductility, the crack pattern, and the failure mode of shear-strengthened beams.

The Effect of Seismic Design on Total Cost of Structural Work for Medium Rise Apartment Building

People believed Malaysia did not experience earthquakes because the country is not in the Pacific Ring of Fire. Then, an earthquake of magnitude M w 6.0 struck Ranau, Sabah, meaning Malaysia was no longer safe from seismic catastrophes. This is especially true when most buildings in Malaysia are not made to withstand the shaking that comes from earthquakes. Considering the seismic design will mean using higher steel reinforcement, immediately raising costs. Hence, this paper studies the cost effect on Sabah’s 6-story reinforced concrete (RC) apartment building. The study had three levels of reference peak ground acceleration: α gR = 0.08 g, 0.12 g, and 0.16 g, and the soil type was D which was classified as Ductility Class Medium (DCM). In the comparison between the non-seismic and seismic models, the findings suggested that the amount of steel reinforcement per 1 m3 of concrete increased by 7% and 31%, respectively. Other than that, the cost increment of structural work increased by 3.3% to 12.7% compared to the non-seismic model.

Flexural behaviour of concrete-basalt FRC beams with steel bars under concentrated load

In this work, the experimental investigation and theoretical analysis on the flexural behavior of steel-reinforced concrete-basalt fiber reinforced concrete (RC-BFRC) beams were conducted. The formulae for calculating the cracking, yielding and ultimate moments, and the deflection of RC-BFRC beams were proposed and validated through experiments. Experimental results demonstrated significant enhancement in load-carrying capacity, deformation ability, and crack resistance for the RC-BFRC beam compared with the ordinary reinforced concrete (RC) beam. And the ultimate deflection of the RC-BFRC beam was slightly smaller than that of the steel-reinforced basalt fiber reinforced concrete (RBFRC) beam at the same fiber content. To gain a deeper understanding of the flexural performance of the RC-BFRC beam, a parametric study was also conducted based on the proposed methods. The results indicated that yield and ultimate moments increased but ultimate curvature in case of under-reinforced failure decreased with the increase of yield strength and amount of steel reinforcement. In case of under-reinforced failure, curvature ductility and energy dissipation of the whole stage decreased with the increase of yield strength and amount of steel reinforcement but increased with the increase of concrete compressive strength and concrete ultimate compressive strain.

A Structural Design Comparison Between Two Reinforced Concrete Regular 6-Level Buildings using Soil-Structure Interaction in Linear Range

Structural engineers commonly design superstructures as fixed at the base and transmit the reactions to the infrastructure in order to design the foundation system and estimate the displacement of the soil while disregarding the change in seismic response that this induces. In this article, the foundation system was transformed into equivalent springs, and the seismic response in the linear range was compared and quantified, obtaining results such as increased periods, increased amounts of steel reinforcement in beams (between 7% and 25%) and columns (between 29% and 39%), an increase in the number of stirrups per linear meter (between 3% and 11% in columns and between 5% and 45% in beams) and drifts (between 1% and 14%), and a decrease in basal shear (up to 20%), which directly affects the design of the structure. This study concludes that the inclusion of the soil-structure interaction is necessary for structural design in the linear range.

Performance of Thin-Wall Synthetic Fiber–Reinforced Concrete Pipes under Short and Long-Term Loading

Abstract Synthetic fibers have been recently used as a replacement for conventional steel reinforcement in concrete pipes to enhance their durability, ductility, shear strength, and flexural strength. However, there is very limited understanding of the long-term performance of thin-wall synthetic fiber–reinforced concrete pipes, as synthetic fiber has material properties that may change with a sustained load over time. This research investigates the performance of polypropylene fiber–reinforced concrete pipe under short and long-term loads in terms of strength, deflection response, strain response, crack width, and crack patterns. Concrete pipes with diameters of 1,200 and 1,500 mm with respective wall thicknesses of 50 and 63 mm were subjected to the short-term three-edge bearing test. To ensure maximum fiber contribution to pipe strength, a 9 kg/m3 fiber dosage was used with different amounts of steel reinforcement. For the long-term three-edge bearing test, a pipe with a diameter of 1,200 mm reinforced with fiber dosage of 9 kg/m3 along with steel reinforcement with an area of 5.7 cm2/m was tested for 30 days at 40 % of the ultimate load (Load Stage 1) obtained from the short-term test, for another 30 days at 50 % ultimate load (Load Stage 2), and subsequently at 70 % ultimate load for a final 30 days (Load Stage 3). Short-term results showed that synthetic fiber was a viable replacement for the steel reinforcement cage, as some of the tested pipe achieved the strength requirement specified by ASTM C76-15a, Standard Specification for Reinforced Concrete Culvert, Storm Drain, and Sewer Pipe. In response to sustained load, the tested pipe initially exhibited a linear response, followed by a stable response with a slight increase in deflection over time. Fiber creep did not significantly increase the crack width or affect the time dependence of the strain, indicating that the fibers adequately transfer the stress in the pipe wall and limit the crack width. The cracks propagated longitudinally at the invert, crown, and springline, where there were high flexural tensile stresses.

Blast behavior of columns built with high-strength concrete and Grade 690 MPa high-strength reinforcement

As part of this study a series of columns built with high-strength concrete and Grade 690 MPa high-strength reinforcement are tested under blast loads using a shock-tube. The performance of the columns is compared to a control set of specimens built with Grade 400 MPa reinforcement. In addition to the effects of concrete and steel type, the effects of longitudinal steel ratio and seismic detailing are also investigated. The results show that concrete strength has limited effects on blast behavior. Conversely, use of high-strength bars significantly enhances column blast performance by reducing displacements and increasing blast resistance, with an ability to reduce the required amount of steel reinforcement. The results further demonstrate that increasing the longitudinal steel ratio and seismic detailing improve the blast behavior of columns built with conventional and high-strength bars. As part of the analytical study the blast response of the columns is predicted using nonlinear single degree of freedom analysis and finite element modelling.

Experimental Behavior of Cracked Reinforced Concrete Columns Strengthened with Reinforced Concrete Jacketing.

Reinforced concrete (RC) columns often need to be strengthened or rehabilitated to allow them to carry the loads applied to them. In previous studies, RC columns have been strengthened by jacketing, without considering the occurrence of cracking. In this study, the behavior of RC columns strengthened externally by jacketing after cracking is analyzed. The accuracy of the existing models was verified by analyzing the performance of fifteen RC columns with different cross-sections to determine the effect of new variables, such as the column size, amount of steel reinforcement, and whether the column was cracked or not, on the effectiveness of strengthening. The analysis demonstrated that this strengthening technique could effectively improve both the ductility and strength of RC column cross-sections. The results indicate that the model suggested by the ACI-318 code can predict the ultimate load capacity of RC columns without strengthening, or strengthened by RC jacketing before or after cracking, with higher accuracy and material efficiency. The RC columns without strengthening met the safety limit of the ACI-318 model. However, for strengthened columns, a reduction coefficient must be used to enable the columns to meet the safety limit, with values of 94% and 76% for columns strengthened before and after cracking, respectively. Furthermore, strengthening after cracking affects the ultimate load capacity of the column, with 15.7%, 14.1%, and 13.5% lower loads for square, rectangular, and circular columns than those strengthened before cracking, respectively.

Investment of Steel Reinforcement Extracted from Destroyed Buildings in Iraq

The number of destroyed cities in Iraq has increased significantly over the last five years. It presents a negative impact on the country's economy on the one hand and on the environment on the other. Reconstruction of these cities requires substantial capital to provide building materials needed for reconstruction and this leads to depletion of natural resources. This paper aims at finding an effective management method that contributes to the investment of the remnants of the components of destroyed buildings, including reinforcing steel, using the building information modelling (BIM) technique. The results showed that the amount of steel reinforcement that can be obtained from the destroyed buildings is enormous. Therefore, these quantities must be addressed through reusing or recycling. The sale of these quantities as recycling materials can provide a large income which can be added to the capital of the project.

Steel Reinforcement and Concrete for Multipurpose Hall Building with Seismic Design

Multipurpose hall is a public building of people assembly for various function and activities. It can be converted to be a temporary shelter during disaster like flood and earthquake. After experiencing tremors from both local and distant earthquakes, the time has come to implement the seismic design to new buildings in Malaysia to ensure public safety. The implementation of seismic design also affecting the cost of construction, especially materials. Therefore, this paper presents the taking off results for reinforced concrete multipurpose hall building with seismic design. In this study two parameters namely as soil type and concrete grade had been considered as design variable. Result from design and taking off demonstrated that the amount of steel reinforcement is strongly influenced by both parameters. The usage of steel for reinforced concrete buildings with seismic design is estimated to increase around 3% to 59% depend on soil type and concrete grade. Results also demonstrated that higher concrete grade require lower amount of steel as reinforcement.

Cost-Based Optimum Design of Reinforced Concrete Retaining Walls Considering Different Methods of Bearing Capacity Computation

This paper investigates the effect of computing the bearing capacity through different methods on the optimum construction cost of reinforced concrete retaining walls (RCRWs). Three well-known methods of Meyerhof, Hansen, and Vesic are used for the computation of the bearing capacity. In order to model and design the RCRWs, a code is developed in MATLAB. To reach a design with minimum construction cost, the design procedure is structured in the framework of an optimization problem in which the initial construction cost of the RCRW is the objective function to be minimized. The design criteria (both geotechnical and structural limitations) are considered constraints of the optimization problem. The geometrical dimensions of the wall and the amount of steel reinforcement are used as the design variables. To find the optimum solution, the particle swarm optimization (PSO) algorithm is employed. Three numerical examples with different wall heights are used to capture the effect of using different methods of bearing capacity on the optimal construction cost of the RCRWs. The results demonstrate that, in most cases, the final design based on the Meyerhof method corresponds to a lower construction cost. The research findings also reveal that the difference among the optimum costs of the methods is decreased by increasing the wall height.

Revising seismic behaviour factors for reinforced concrete bridge design in the longitudinal direction using multi-objective evolutionary algorithms

Seismic behaviour factors represent the ratio between the strength of a structure, assuming it always maintains an elastic behaviour, and the strength demand with plastic behaviour and consequent loss of stiffness, at the seismic target displacement. This value is closely related to ductility and to energy dissipation due to hysteretic behaviour. The use of behaviour factors allows to design structures with elastic models, without having to explicitly account for material non-linearity while taking advantage of ductility. However, the definition of these values is not easy, and is dependent on several factors. In bridges, these factors can be, among others, regularity of the bridge in terms of pier height, concrete and steel quality, size of elements and amount of steel reinforcement, pier confinement, etc. These factors influence ductility demand and available ductility in different ways and through multi-objective optimization (MOO), the infrastructure solutions that maximize the use of the available ductility under a given earthquake action and for a given bridge superstructure, pier height scheme and ductility class according to Eurocode 8—part 2, can be obtained. Those optimized solutions, which are obtained through the minimization of steel and concrete in the piers as concurrent objectives, are associated with the maximum behaviour factors that can be used in the design of a given bridge and can be compared with the values recommended by EC8—part 2. Without loss of generality, the methodology is applied to a set of case-studies composed of RC bridges with four 30-m spans and circular piers, analysed in the longitudinal direction and without accounting for abutment effects. With the results from the MOO, the behaviour factors associated to solutions with different ductility levels and pier irregularity schemes are calculated and equations are derived, relating the obtained behaviour factors with a pier irregularity measure and ductility level. The results also show the importance of the choice of stiffness used in the design process.

Effect of Casing and High-Strength Reinforcement on the Lateral Load Transfer Characteristics of Drilled Shaft Foundations

AbstractIncreased seismic flexural demands on drilled shaft foundations have led to significant increases in the amount of steel reinforcement, leading to a greater number and/or larger sized steel...

Concrete slab fragmentation after bullet impact: An experimental study

The response of nonreinforced concrete to high-speed flying fragments depends on many factors such as composition, geometry and boundary conditions of the obstacle. In this study, the authors verified experimentally a series of concrete slabs with various aggregate types and amounts of steel reinforcement. The material properties were previously developed and verified during the laboratory experiments with standard cubic specimens. Moreover, the main goal of this research was the verification of high-strength concrete plates using different kinds of aggregate, that is, traditional gravel, granite, basalt and amphibolite subjected to the military bullet impact. It is known that the aggregate filled about 70% of total concrete volume, and therefore, the properties of aggregate, like density, strength and surface will be the main factors influencing the concrete strength and further concrete resistance to projectiles. The research presented shows that the type and shape of aggregate determined the conditions of concrete failure. The outcomes show that the obtained compressive strength varied between 60 and 80 MPa. In the second stage of the test, randomly distributed reinforcement was added to selected concrete mixtures. Hooked steel fibres with an aspect ratio of 50 in the amounts of 50 and 100 kg per cubic metre were applied. The influence of steel fibres on the concrete properties was verified in compressive and splitting strength tests. On the basis of preliminary laboratory tests, the final slab specimens, with the dimensions of 0.5 × 0.5 m and 0.05 m thickness, were produced. The final verification was performed in the real field conditions using the most popular military bullet, whose kinetic energy was more than 2000 J. The measurements of the initial and final velocities of the bullets and concrete fragments were obtained using high-speed camera measurement equipment. The final failure of the slabs was presented as the primary outcome.

ASSESSING THE INCREASE IN BEARING CAPACITY OF BORED PILES IN SANDY SOIL USING EXPANSIVE ADDITIVES

The pile foundation is usually designed to exceed the weak soil to the strong stratum. There is very close relation between the pile capacity and surrounding soil conditions. In cohesionless soil, the bored pile is effecting surround soil by loosening deposits through a combination of pile volume replacement and exist of pile case used for installation of bored pile. In this study, the improvement of the weak soil that surrounds the pile and observing the effect of improvement on pile increase the skin friction of the bored pile capacity for bored pile carried out. This study conducts research into the use of expansive additives in concrete bored piles. The aim of this project was to investigate how Na2Co3 as an additive in concrete can increase the shaft resistance of a bored pile. Several tests were conducted on concrete single piles with a variation of length to the diameter ratios and different percentages of soda ash additives. All tests were made in dry, sandy soil at loosening state. All tests showed that the shaft capacity could be increased using expansive additives due to increase the volume of the pile or enlargement of pile volume during concrete setting; it was also concluded that the shorter expansive piles could be able to achieve the same pile capacity as a longer conventional pile. This would lead to reductions on the volume of concrete poured, the amount of steel reinforcement used and the amount of soil excavated. Therefore, construction costs can be decreased and construction times can be shortened.

Computer Program for Reinforced Concrete Bar Bending Schedulling to Increase Efficiency of Reinforcement

The construction project consists of several components, one of them is a reinforced concrete. Reinforced concrete construction contributes to 30% of the total budget or 80% of the total civil work. Meanwhile, judging from the proportion provided by the use of steel reinforcement reaches 45% of the contribution of the use of reinforced concrete. The use of steel reinforcement that is not planned well lead to cost overruns and the resulting increase in waste production. The waste is unlikely to be used again because the length does not qualify the existing needs. In terms of environmentally wasteful use of steel reinforcement is not aligned with the slogan green construction. According to the Environmental Product Declaration (EPD) in 2012 the production of steel reinforcement produces CO2 gas 430 kg CO2 eq /ton. On the other hand, local contractors in Surakarta never planning the use of steel reinforcement. Contractors plans and cuts of reinforcement. It increase potential construction waste due to inaccurate planning. Therefore in this study are create a computer program to design a model of bending reinforcing steel. Finally, steel reinforcement planning are better obtained. This program is applied to create a Visual Programming software, ACAD, Crystal Report, and Microsoft Database. Visual Programming is used as a place store of scripts and programs to connect database and Crystal Report. Microsoft database used to store data and Crystal Report are employed to display the results of the program. Furthermore, scheduling program of bar bender can be created. the time of production of reinforcement detailed is faster. By inputing a cross-section measurements and information reinforcement used various bending of reinforcement pieces are produced automatically. Crystal Report output can be made a flexible and attractive form to look at as well as the ability to transfer to other programs such as MS Word, Excel and PDF. Output can display different forms of reinforcement pieces with illustrated picture and the required amount of steel reinforcement in accordance with the dimensions and types.

Seismic performance of masonry strengthened with steel strips

Strengthening of unreinforced masonry structures to improve their seismic performance is getting attention of civil engineers across the world. In this study, laboratory tests were carried out to investigate the seismic performance of unreinforced burnt clay masonry wall panels strengthened with externally anchored steel strips. Six masonry panels having an aspect ratio of 0.7 were constructed. First masonry panel was unreinforced reference specimen and remaining specimens were strengthened with steel strips using different steel ratios and mesh patterns. Three specimens were strengthened with steel strips on one face and two specimens were strengthened with steel strips on both sides. All the specimens were tested under lateral cyclic loading at constant axial pressure to determine seismic performance. The test results revealed a significant improvement in energy dissipation, ductility and lateral strength of strengthened masonry wall panels. The main contributing factors in performance improvement were 1) amount of steel reinforcement, 2) mesh pattern and 3) single or double side application of steel strips. The proposed steel strips strengthening technique is quite simple and economical which involves external application of steel strips and does not alter the mass significantly. The simplicity, cost effectiveness and efficacy of the technique can help the local designers and engineers to enhance seismic performance of existing masonry structures.

Evaluation of the influence of design factors on the CO2 emissions and costs of reinforced concrete columns

Reinforced concrete (RC) is one of the structural materials that produce environmental pollution. The objective of this study is to present design guidelines for reducing CO2 emissions or costs associated with structural materials in the structural design phase of RC columns. After identifying the cross-sections of RC columns with the minimum CO2 emissions or costs while satisfying the structural design conditions via a parametric study, the influence of the design factors (i.e., concrete strength, steel reinforcement strength, cross-section size, and amount of steel reinforcement) on the CO2 emissions and costs of RC columns are investigated. The results confirm that increasing the strength and amount of steel reinforcements is efficient for sustainable design, whereas increasing the strength of the structural materials and the amount of concrete is efficient for economical structural design.

Seismic In-plane performance of retrofitted masonry walls

Retrofitting of masonry to improve its seismic performance is the focus of research community all around the globe. In the present work, a new masonry retrofitting technique using externally anchored steel strips mesh is presented. An extensive experimental programme was carried out to study the effects of proposed technique on masonry lateral strength, ductility, energy dissipation, response and damping factor under lateral cyclic loading. A total of twenty tests were carried out; 1) twelve were lateral cyclic tests, 2) four monotonic lateral tests and 3) four pure compression tests. The test results were analysed in five separate groups and this paper presents the analysis of group 3, which deals with the effect of steel retrofitting of un-reinforced masonry wall panels on its seismic performance. Six single leaf panels with aspect ratio of 0.67 were constructed using same type of material and workmanship. It was observed that amount of steel reinforcement and meshing pattern of steel strips had significant effect on seismic performance and failure modes. The simplicity, cost effectiveness and efficacy of this proposed technique could help the local designers and engineers to enhance seismic performance of existing masonry structures.

Sensitivity of Natural Frequencies to Composite Effects in Reinforced Concrete Elements

This article attempts to explain the effect of composite action in reinforced concrete (RC) elements on the natural frequencies. Natural frequencies are governed by the relationship between the physical properties of RC elements and its composite action. The softening of concrete in tension, compression, and pre- and post-yielding steel behavior are considered. The bonding action between steel and concrete under loading and unloading conditions is also taken into account. The assumption of the increase in stiffness of RC elements in tension due to bond action is investigated by tests on two RC beams. Both static and modal testing were carried out after inducing different levels of damage in the beams. Results show the validity of the assumption made due to composite action. Mode 1 can be an indicator for bond action behavior and for predicting the yield state of steel in the RC beams. Mode 2 behavior is governed by the amount of steel reinforcement, where for maximum steel ratio it will be affected by concrete softening, while for minimum steel ratio it will be affected by both concrete softening and bond action. Modes 3 and higher can be indicators for concrete softening.

Prediction of shear strength of FRP-reinforced concrete beams without stirrups based on genetic programming

The use of fibre reinforced polymer (FRP) bars to reinforce concrete structures has received a great deal of attention in recent years due to their excellent corrosion resistance, high tensile strength, and good non-magnetization properties. Due to the relatively low modulus of elasticity of FRP bars, concrete members reinforced longitudinally with FRP bars experience reduced shear strength compared to the shear strength of those reinforced with the same amounts of steel reinforcement. This paper presents a simple yet improved model to calculate the concrete shear strength of FRP-reinforced concrete slender beams (a/d>2.5) without stirrups based on the gene expression programming (GEP) approach. The model produced by GEP is constructed directly from a set of experimental results available in the literature. The results of training, testing and validation sets of the model are compared with experimental results. All of the results show that GEP is a strong technique for the prediction of the shear capacity of FRP-reinforced concrete beams without stirrups. The performance of the GEP model is also compared to that of four commonly used shear design provisions for FRP-reinforced concrete beams. The proposed model produced by GEP provides the most accurate results in calculating the concrete shear strength of FRP-reinforced concrete beams among existing shear equations provided by current provisions. A parametric study is also carried out to evaluate the ability of the proposed GEP model and current shear design guidelines to quantitatively account for the effects of basic shear design parameters on the shear strength of FRP-reinforced concrete beams.