Compression Reinforcement Research Articles

Prediction of punching shear capacity of concrete slabs reinforced with additional middle-thickness rebar mesh

This paper aims to evaluate the influence of using additional middle-thickness rebar mesh (mid-mesh) on improving the punching shear behavior of interior slab-column connection. Sixteen two-way slabs were cast and tested including different flexural, compression, and mid-mesh reinforcement ratios at different levels of concrete strength. The performance of code-based expressions in predicting the punching shear capacity of reinforced concrete flat plates was also ascertained. The results indicated that using additional mid-mesh showed an increase in the punching shear capacity of slabs reached up to 17.7%. The results also indicated that the ACI 318-19 and CSA A23.1-19 codes underestimate the punching shear strength of tested slabs. Eurocode showed the closest predictions of the ultimate shear load compared to the other design codes investigated in this study. The authors also proposed an equation that can help the designers/engineers to accurately predict the punching shear capacity of intermediate slab–column connection with and/or without additional mid-mesh reinforcement.

Dynamic response of GFRP-reinforced UHPC beams under close-in blast loading

Combined use of ultrahigh-performance concrete (UHPC) with glass fiber reinforced polymer (GFRP) reinforcement has the potential for further blast resistance enhancement of reinforced concrete (RC), due to the improved toughness of UHPC and the high strength-to-weight ratio of GFRP. This paper aims to fill the gap on the effectiveness of GFRP bars on the blast response of UHPC beams. The blast resistance of UHPC beams built with GFRP bars (UHPC-GFRP beams) is experimentally and numerically investigated in this paper. In the experimental scheme, twelve beams strengthened with various types of concrete and reinforcement are tested under near-field explosions. The properties of UHPC beams reinforced with GFRP bars are compared with specimens reinforced with normal-strength steel (NSS) and high-strength steel (HSS) bars. GFRP bars reduce the maximum displacements, which enhances the blast performance of UHPC beams. However, reinforcing UHPC beams with GFRP bars results in large rebound displacements. In addition, the coupled finite element model is adopted to predict the response of test beams. The numerical method using LS-DYNA achieves reasonable accuracy. Moreover, the damage process, energy characteristics, reaction forces, stress response and the effect of the compressive reinforcement are examined to better depict the damage mechanism of the UHPC-GFRP beams.

MODELING OF CROSS-SECTIONS OF WOODEN ELEMENTS FOR DIFFERENT OPTIONS AND PERCENTAGES OF REINFORCEMENT

A detailed analysis of literary sources on the study of strengthening of wooden elements by various methods was carried out.
 The calculation sequence of wooden elements reinforced with glued metal elements is proposed. An algorithm for determining the "moment-curvature" graph using optimized wood deformation diagrams is proposed. Calculations were carried out for various forms of beam cross-sections. Calculations of the cross-section were carried out and "moment-curvature" graphs were determined for different options for the reinforcement of the wooden element (with the reinforcement of the compressed zone, the stretched zone, as well as with the reinforcement of both zones). Schedules were determined with different percentages and methods of reinforcing elements. It was established that the best result of reinforcement occurs when reinforcing compressed and stretched zones, less effective when reinforcing a beam in a compressed zone, the smallest effect of reinforcing a stretched zone.
 To simulate the work of reinforced wood, the mechanical characteristics of "pine" wood with a moisture content of 12% and metal, namely the characteristics of A400S reinforcement, were used. Moment-curvature plots are given for cross-sections with different percentages of reinforcement and reinforcement in compression and tension zones. An increase in the load-bearing capacity of a bending wooden element due to various options and percentages of reinforcement reinforcement is presented.
 It is necessary to note the change in the shape of the "moment-curvature" graph with symmetrical reinforcement, namely, with an increase in the percentage of reinforcement, its shape approaches a straight line. Based on the analysis, conclusions were drawn. The volume of further experimental and theoretical research on this issue is given.

Seismic performance of a ring–beam connecting concrete-filled steel columns with RC frames

The seismic performance of a ring–beam connection system to integrate concrete-filled steel tubular columns and reinforced concrete (RC) frames was studied. Physical experiments on two specimens were conducted under monotonic and cyclic loading. The results showed the connection system had a displacement ductility ratio of 4.68 and an energy dissipation coefficient over 2.0. A finite-element model was established and the numerical and experimental results were compared in terms of skeleton curves and stiffness degradation trends. Parametric studies were then performed to evaluate the effects of the axial compressive force ratio, concrete strength and reinforcement ratio of the ring–beam joint (RBJ) and the reinforcement ratio of the frame beam on the seismic performance of the proposed RBJ connection system. The results showed that an increase in the axial compression ratio or strength of the concrete material improved the initial stiffness and strength of the connection system. The effects of the RBJ reinforcement ratio and the frame beam reinforcement ratio on seismic performance were negligible.

Perencanaan Bak Penampungan Air yang Berasal Dari Mata Air di Lingkungan Universitas Jambi

Jambi University is one of the State Universities in Indonesia which is currently in the phase of sustainable development which is currently focusing on increasing development, especially water resource infrastructure. Planning for water reservoirs with reinforced concrete is an option in long-term infrastructure planning. The planned reservoir is in the form of a reservoir that functions as a container for storing clean water in the water treatment system at the Jambi University. Planning focuses on the design of the capacity and structural elements of the reinforced concrete reservoir. Planning refers to ACI-350M using the LRFD method, as well as SNI 7509:2011. The reservoir capacity is planned according to (Al-Layla et al., 1977)at 39% of the maximum water discharge, and the structural elements of the reservoir are planned in the form of beams, columns, upper, lower plates and walls. Based on the design, the reservoir capacity is 216 m3 with a length of 12 m, a width of 6 m and a height of 3.5 m. In planning the structural elements used concrete quality 21 MPa with the type of reinforcement BJTP-28. Based on the design results, the column size is 20 cm x 20 cm with 4D12 reinforcement details, then for beam sizes 30 cm x 20 cm using 4D12 for tensile reinforcement and 3D12 for compression reinforcement, and for plates using a thickness of 150 cm with reinforcement details D12-150 for top plate and D12-200 for bottom plate and wall plate.

CALCULATION OF OFFCENTRALLY COMPRESSED ELEMENTS

A large number of calculation formulas have been proposed to describe the deformation diagrams of masonry and concrete. The data indicate the possibility and expediency of using full masonry deformation diagrams to calculate the strength and deformations of stone and reinforced stone pillars. Experimental samples and stone pillars were tested. The samples were of five types and differed among themselves in the location of reinforcement and the reinforcement ratio, as well as in the method of loading – axial or off-center compression with different eccentricity. In the paper, experimental and calculated longitudinal deformations of masonry and reinforcement for samples of different groups. These data testify to the possibility and expediency of using full masonry deformation diagrams to calculate the strength and deformations of stone and reinforced stone pillars. As the amount of reinforcement in the stretched zone increases, most of the section works on the descending branch of the diagram. The size of the compressed zone increases, which is equivalent to a decrease in eccentricity. Reinforcement of the compressed zone with reinforcement increases the strength of sections with double reinforcement. The shapes of the stress profiles in the masonry practically do not depend on the presence of compressed reinforcement. The calculation establishes the expediency of the installation and the degree of saturation of the stretched and compressed cross-sectional areas with reinforcement. At small eccentricities, when the force is applied within the core of the section, saturation of the compressed zone with reinforcement leads to a noticeable increase in the strength of the section. At large eccentricities, saturation of the compressed zone with reinforcement is ineffective.

Regularisation methods for modelling flexural dominant lightly reinforced concrete walls

Localisation can occur in distributed plasticity fibre models when a strain-softening response at the section restricts the spread of damage due to the unloading of stress in adjacent sections/elements. Past studies have developed regularisation schemes for the concrete compression response and reinforcement tension response to achieve mesh objective simulations for the failure of reinforced concrete (RC) walls. However, for walls designed with low amounts of longitudinal reinforcement, the response and failure are controlled by the tensile behaviour, including concrete cracking and reinforcement fracture. The aim of this study was to develop reliable regularisation approaches that could be implemented into fibre models to simulate the cracking and reinforcement fracture response for lightly reinforced concrete walls. Methods for regularisation of both the reinforcement and concrete material properties using a fracture energy method were proposed to minimise the effect of element size on the strain localisation during nonlinear analysis of lightly reinforced concrete walls. The proposed regularisation techniques were validated against the measured response of tested lightly reinforced walls subjected to both monotonic and cyclic loading to ensure that both the cracking strength, ultimate strength, and ultimate drift capacity could be accurately simulated. The local strain response was also investigated to highlight the post-processing of model outputs required to achieve objective simulation results. The results indicate that the models implementing the proposed regularisation of concrete and reinforcement constitutive models could accurately predict the global hysterical response as well as the local strain response of lightly reinforced concrete walls.

Numerical analysis of flexural and shear behaviors of geopolymer concrete beams

Geopolymer concrete (GPC) is obtained by activating industrial wastes such as fly ash with chemical liquids such as sodium hydroxide (NaOH) and sodium silicate (Na2 SiO3). In order to use environmentally friendly GPC obtained from industrial wastes instead of portland cement concrete (OPC), its behavior in structural elements is important and should be investigated in detail. Load-displacement characteristics, flexural and shear stiffnesses and crack development of samples were obtained by numerical analysis. The GPC beams to be an alternative to OPC beams, their mechanical properties and fracture modes must be at least as much as OPC. As a result of the analyses, it was determined that the 110x20x15 cm GPC beams with compression reinforcements of 2Φ8 and tension reinforcements of 2Φ8, 3Φ14 and 2Φ18, respectively, showed similar flexural, shear and crack development with OPC beams. Simulations of GPC beams were made up to the breaking point, contributing to the understanding of its behavior.

Span‐to‐depth ratio limits for deflection control of reinforced concrete elements

Indirect deflection control usually applies the limitation of the span-to-depth ratio. The procedures that have developed in the past decades have mostly been derived for predefined values of some of the relevant parameters. Assigning values to parameters simplifies the application of criteria. Predefined values may not be suitable for all design situations and some of the recently published procedures allow direct selection of relevant parameters. This paper offers new expressions for span-to-depth ratio limits for deflection control. Expressions include cross-section size, area, and position of tensile and compressive reinforcement, mechanical and long-term properties of concrete and deflection limit. The load level is represented by the stress in the tensile reinforcement so that the ratio of live and total load can be arbitrary. The dimensionless form of deflection calculation by numerical integration of the mean curvature according to Eurocode 2 is used to formulate the expressions. The proposed procedure is verified with a large number of numerical simulations for different combinations of inputs. Measured long-term deflections, available from the literature, are also used to test the procedure. The expressions are suitable for both deflection control and conceptual design.

Repairing half-loaded flat slabs against punching shear using steel stiffeners

In this paper, a repairing system was implemented on flat slabs that have been suffered from punching shear stresses due to loading to half their capacities. The repairing system primarily relies on retrofitting the damaged concrete by adding steel stiffeners of different dimensions and numbers. The experimental procedure included casting four flat slabs of identical flexural reinforcement and dimensions of (1.5 × 1.5 × 0.1) m. The efficiency of the proposed repairing system was evaluated experimentally in terms of shear capacity, deformation properties and crack behavior. The experimental results were utilized to calibrate a nonlinear finite element model which was constructed using (ABAQUS). The finite element model was then used to conduct a parametric study to check the influence of changing the compressive strength and flexural reinforcement on the shear capacity. Test results showed that the proposed system was effective in repairing the damaged flat slabs in terms of punching shear, in which enhancements in both the strength and deformation capacities were recorded by about 74.2% and 66.4%, respectively. Furthermore, the numerical investigation revealed that increasing the concrete compressive strength and flexural reinforcement ratios has a considerable positive effect on the punching shear capacity of the slab.

Progressive compression and weight reinforcement for spiking neural networks

SummaryNeuromorphic architectures are one of the most promising architectures to reduce the energy consumption of tomorrow's computers. These architectures are inspired by the behavior of the brain at a fairly precise level and consist of artificial spiking neural networks. To optimize the implementation of these architectures, we propose in this article a novel progressive network compression and reinforcement technique. This technique consists of two functions: progressive pruning and dynamic synaptic weight reinforcement, which we apply after each training batch. The proposed approach delivers a highly compressed network (up to 80% of compression rate) while preserving the network performance when tested with MNIST.

A New Approach for Determining the Curvature Ductility of Reinforced Concrete Beams

Abstract This paper presents a numerical parametric study of the moment-curvature and curvature ductility of doubly-reinforced beams with different parameters. The effects of the strength of the concrete and the amount of the reinforcement, including the tensile and compression reinforcement on the complete moment-curvature behavior and the curvature ductility factor of the beam sections, have been studied. A new predictive formula for the ductility factor of beam sections that considers the different parameters has been developed. In a continuation of the study, the flexural ductility of beams designed with different parameters according to the ductility factor proposed by different researchers was investigated. Based on the results of the numerical analysis, the proposed predictions for the curvature ductility factor were verified by comparisons with other predictive formulas. The proposed formula offers fairly accurate and consistent predictions for the curvature ductility factor of beam sections. It is shown that the concrete’s compression strength and the amount of reinforcing steel, including the compression reinforcement ratios, have an effect on the curvature ductility factor of beam sections.

Numerical study and proposal of new design equations for steel decking concrete slabs subjected to fire

This paper presents a numerical study on structurally continuous steel decking concrete slabs subjected to fire. This is an important subject for improving the fire design methods of this type of elements. Slabs with tension, compression and/or both steel reinforcement types have been tested. The results of twelve full-scale slab fire resistance tests carried out by the authors have been used in the calibration of the numerical models. Despite the compression rebars being more thermally protected, the use of tension rebars proved to be a good design solution, because just from the initial 5 min of fire, a detachment of the steel deck was registered. In this sense, slabs without tension rebars performed like a non-reinforced concrete slab. The detachment of the steel decking suggests that this type of slabs should not be fire designed as a composite element. There is no interaction between the steel decking and the concrete just from the beginning of the fire exposure. Nevertheless, when the steel decking detaches and stops contributing to the mechanical resistance of the slab, it continues to work as a thermal barrier. Another important conclusion is that the simple calculation method of EN 1994–1-2 needs an update for taking into account these phenomena. A new methodology for the mechanical and thermal design of these slabs in case of fire is proposed.

Flexural Behavior of a Novel Textile-Reinforced Polymer Concrete.

Textile reinforced concrete (TRC) has gained attention from the construction industry due to its light weight, high tensile strength, design flexibility, corrosion resistance, and remarkably long service life. Some structural applications that utilize TRC components include precast panels, structural repair, waterproofing elements, and façades. TRC is produced by incorporating textile fabrics into thin cementitious concrete panels. Premature debonding between the textile fabric and concrete due to improper cementitious matrix impregnation of the fibers was identified as a failure-governing mechanism. To overcome this performance limitation, in this study, a novel type of TRC is proposed by replacing the cement binder with a polymer resin to produce textile reinforced polymer concrete (TRPC). The new TRPC is created using a fine-graded aggregate, methyl methacrylate polymer resin, and basalt fiber textile fabric. Four different specimen configurations were manufactured by embedding 0, 1, 2, and 3 textile layers in concrete. Flexural performance was analyzed and compared with reference TRC specimens with similar compressive strength and reinforcement configurations. Furthermore, the crack pattern intensity was determined using an image processing technique to quantify the ductility of TRPC compared with conventional TRC. The new TRPC improved the moment capacity compared with TRC by 51%, 58%, 59%, and 158%, the deflection at peak load by 858%, 857%, 3264%, and 3803%, and the toughness by 1909%, 3844%, 2781%, and 4355% for 0, 1, 2, and 3 textile layers, respectively. TRPC showed significantly improved flexural capacity, superior ductility, and substantial plasticity compared with TRC.

The shear strength of concrete beams hybrid-reinforced with GFRP bars and steel bars in main reinforcement without shear reinforcement

Abstract The investigation of the structural performance of reinforced concrete members in the construction process has become a critical issue for Hybrid GFRP bars with steel bars. The ultimate concrete shear strength of reinforced concrete beams contains both GFRP bars and Steel bars in main reinforcement are a main task of work. This paper examines the effect of sharing the fiber-reinforced polymer (FRP) bars with steel bars for reinforced concrete (RC) structures on the concrete shear strength of RC beams. Fourteen RC beams without shear reinforcement were constructed and tested up to failure. The test beams included two steel-RC beams, one GFRP-RC beam, and eleven steel bars and GFRP bars (hybrid GFRP/steel)-RC beams. The main parameters were the reinforcement ratio, shear span to depth ratio, depth of the beam, concrete compressive strength, and compression reinforcement. The test results are presented in terms of crack patterns, failure modes, load-deflection, and load-strain behavior. The test results showed that hybrid GFRP/steel bars causing significant improvement in the ductility with reduction of the deformation comparing with an only steel bar in main steel in tested beams. The dowel action can play a major role in the process by which shear is carried in a beam. Finally, the initial proposal equation that calculates the shear strength of hybrid reinforced elements can serve as a guideline for the introduction of hybrid bars (GFRP and Steel) at the main reinforcement in RC beams.

Taking into account the operation of compressed composite polymer reinforcement when calculating the strength of compressed elements according to the deformation model

Taking into account the operation of compressed composite polymer reinforcement when calculating the strength of compressed elements according to the deformation model

Strengthening effect of prestressed near-surface mounted CFRP bar system according to material properties of aged reinforced concrete beams

The flexural performance improvement of age-deteriorated reinforced concrete (RC) beams by a near-surface mounted carbon fiber-reinforced polymer (NSM CFRP) bar system was experimentally investigated. Ten 6.4 m long RC beams were fabricated and tested in four-point bending using different concrete compressive strengths to distinguish between old and new concrete, different steel reinforcement ratios to reflect deterioration with age, and different quantities of prestressed and non-prestressed CFRP bars. The results indicated that the ultimate strengths of the NSM CFRP-strengthened RC beams were up to twice that of the un-strengthened control beam, and the strengthening effect increased with the material properties of the RC beam. A finite element model of the strengthened RC beam was constructed and verified against the experimental results, then used to conduct a parametric study of the influence of the concrete compressive strength and steel reinforcement ratio on the strengthening effect of the prestressed NSM CFRP bar system.

Comparison of the effect of GFRP and steel reinforcement in concrete members subjected to compressive stress

Composite materials became more popular and commercially available as reinforcement for concrete elements. Fibre Reinforced Polymer (FRP) bar is an excellent thermal and electrical insulator with high tensile strength and low weight. These assumptions make them a possible substitution for steel reinforcement. Moreover, GFRP is not responsible to corrosion for that are suitable for structures with high humidity and unfavorable environment. GFRP is easier to handle due to its low weight. Also, it has electromagnetic neutrality. But it has some disadvantages. It has a low modulus of elasticity and sensitivity to elevated temperatures. Another drawback and uncertainty with designing is the impact of an alkaline environment, which decreases the long-term strength of GFRP bars. This paper describes a pre-experiment study of concrete elements resistance. The analysis is performed for a cross-section of 200x150 mm for a short concrete column with steel and GFRP reinforcement. The study compares P-M diagrams for steel reinforcement and GFRP reinforcement with different reinforcement ratios. Other characteristics such as tensile strength and modulus of elasticity must be considered to design the GFRP reinforced concrete element. The study also considers the contribution of GFRP reinforcement in compression. The analysis has shown, the shape of interaction diagrams of steel and GFRP reinforcement are significantly different.

Parametric Study of Concrete Members with GFRP Reinforcement Subjected to Bending and Axial Force

The paper deals with the possible replacement of steel reinforcement by GFRP reinforcement for concrete elements subjected to bending moment and compressive axial force. For the last 15 years, Fibre Reinforced Polymer (FRP) bars became more popular and commercially available as reinforcement for concrete elements. Composite FRP materials are still new in construction and many engineers are not familiar with their properties and behaviour. FRP has certain advantages over steel reinforcement. It is a durable material that is not subject to corrosion, does not conduct heat, is an electrical insulator and conducts electrical current, and is non-magnetic. In contrast, FRP also has certain deficiencies such as sensitivity to higher temperatures, alkaline environments, and reduction of mechanical properties at high levels of long-term stress. In the case of FRP reinforcements, the plastic branch is missing in the σ-ε diagrams, what leads to a sudden failure of the reinforced concrete element, either by tensile rupture of the reinforcement or by crushing the concrete. The most used FRP reinforcement is made of glass fibres - GFRP reinforcement. The paper deals with the possible replacement of steel reinforcement by GFRP reinforcement for slab and beam elements. The text describes a parametric study for different reinforcement ratio with GFRP reinforcement and steel reinforcement. The study is performed for a cross-section of 500x500 mm for a column element and a cross-section of 1000x250 mm for a slab element. The effect of longitudinal GFRP reinforcement in elements under compression was investigated. The study contains a comparison of interaction P-M diagrams of concrete elements with steel and GFRP reinforcement. For design of GFRP reinforced concrete elements, it is necessary to consider different material characteristics such as tensile strength and modulus of elasticity. The contribution of the GFRP reinforcement in compression was neglected due to the anisotropic nature of the GFRP reinforcement and the low modulus of elasticity. The main reference basis for the elaboration of a parametric study is the fib Bulletin No. 40.

Meningkatkan Daya Dukung Tiang Pondasi Minipile Persegi Pada Gedung Kantor Ngasem Kabupaten Kediri Menggunakan Metode Mayerhoff

The foundation is one part under the building that has a very important role. The choice of the type of foundation is something that needs to be considered. One type of foundation that is widely used is the minipile foundation. Minipile foundation itself is a type of foundation that is used if the load received from the superstructure is not too heavy and the hard soil type is at a depth of between 5-10m. The purpose of this study was to plan the bearing capacity of the minipile foundation pile in the PT. BPJE in Ngasem, Kediri Regency. The building is planned to be used as an office building. The planned sub-building includes foundation planning with a mini-square building with a cross-sectional dimension of 20x20. The calculations carried out include the calculation of the bearing capacity of the foundation using the Mayerhoff method, the calculation of the flexural factor and the calculation of reinforcement. The calculation results (sigma Vertical Ultimate) Vu = 114.78 tons. With bending factor tk = 286.95 kg /. The reinforcement in the pile cap for the x direction of tensile reinforcement = D16–170 and compression reinforcement = D16–250 while for tensile reinforcement in the y direction = D16 - 170 and compressive reinforcement = D10 - 250. Thus, the results of the planning can be used as a reference for the implementation of building construction. office of PT. BPJE in Ngasem, Kediri Regency.