Support Beam Research Articles

Advanced Strengthening of Steel Structures: Investigating GFRP Reinforcement for Floor Beams with Trapezoidal Web Openings

Enhancing existing steel structures becomes imperative upon alterations in usage or geometric configurations, such as introducing web openings in floor beams to accommodate various services. The utilization of welded steel plate and conventional strengthening methods often presents challenges, which may be mitigated through the adoption of composite materials like Fiber Reinforced Polymers (FRP). However, research on the application of FRP to steel beams with web openings remains limited, predominantly focusing on beams with rectangular openings of modest dimensions. This study delves into the application of Glass Fiber Reinforced Polymers (GFRP) to strengthen reinforced steel floor beams featuring trapezoidal openings. Leveraging a rigorously validated numerical model derived from previously published findings by a contributing researcher, the investigation showcases that the proposed GFRP reinforcement scheme exhibits performance comparable to conventional steel plate welding techniques, while preserving the inherent strength of the original solid beams.

Bending behavior of RC beams with Fe-SMA strip reinforcement

This paper presents an experimental investigation on reinforced concrete beams with different slenderness strengthened with unbonded Fe-SMA strips. The retrofitting system acts as an external prestressed tendon with a mechanical anchorage. In a first step, the strips are positioned against the concrete bottom surface and fixed against the concrete substrate with a direct fastening system. Activation and hence prestressing of the strips is performed with a gas torch and a subsequent temperature control. The concrete elements are afterwards subjected to 4-point bending up to failure. The aim of the investigation is to assess the structural behavior of the retrofitted members as well the additional strain and stress development in the Fe-SMA strips under additional loading after prestressing. Stress increase in the external strip resulting from the flexural loading has a direct influence on the failure mechanism in a sense that the ultimate stress is governed by the anchorage resistance. The experimental investigation for instance shows the effect of the beam slenderness and reinforcement ratio on the failure mode.

横梁加筋方式以控制双T板端部裂缝的技术研究

横梁加筋方式以控制双T板端部裂缝的技术研究

Effect of chlorine salt erosion on flexural performance of GFRP and steel bars hybrid reinforced beams

Hybrid reinforced beams subjected to chloride salt erosion are susceptible to chloride ion infiltration, leading to corrosion of longitudinal reinforcement within the beams and thus impacting their flexural capacity. This study aims to assess the impact of varying reinforcement material area ratio and chloride salt erosion environments on the flexural behavior of hybrid GFRP-steel reinforced concrete beams. This is achieved through bending tests conducted on one reinforced concrete beam and seven concrete beams incorporating hybrid GFRP-steel reinforcement, coupled with finite element analysis. The results demonstrate that the better reinforcement material area ratio (RMAR) for hybrid reinforced beams is 1.36. When compared to the non-eroded beam, beams exposed to chloride salt erosion consistently exhibited a failure mode characterized by steel yield-concrete crushing failure, and the development of cross-sectional strain of the erosion beams aligning with the assumption of a plane section. The more severe erosion conditions lead to increased beam deflection, reduced maximum crack width, and reduced load-bearing capacity. Based on these findings, formula for accurately predicting the upper limits of load-induced crack widths at all levels and the formula for the load carrying capacity are deduced. Moreover, the feasibility of the nonlinear spring finite element method is validated. The results of this study offer significant reference value for the design and practical application of hybrid reinforcement beams.

Numerical study of steel–concrete composite beams strengthened by CFRP plates with prestressed unbonded reinforcement system

This work developed a three-dimension refined finite element (FE) model to study the flexural behavior of steel–concrete composite beams strengthened with CFRP plate by prestressed unbonded reinforcement (PUR) system. The numerical result has excellent agreements with the experimental results on the failure mode, overall load–deflection response and strain development at mid-span section as well as CFRP plates. The verified FE model was applied to carry out a comprehensive parametric study, evaluating the effects of sectional area, prestress level and profile of CFRP plate, to investigate the optimum parameter range of PUR system for beam reinforcement. It is found that the yielding load rises as the sectional area, prestress level, and pillar spacing of CFRP plates increase. Besides, the ultimate bearing capacity of beam can be efficiently improved by increasing the sectional area of CFRP plates, while the mid-span deflection and ductility were maintained at failure. Moreover, as the prestress level of CFFR plate increases, the bearing capacities of reinforced beams marginally rise but the ductility markedly decreases. The ideal prestress level for strengthening is considered as 10 %∼30 %. Furthermore, the profile of CFRP plate has significant impact on failure of reinforced beams, but has little effect on ultimate load. The results of parametric studies are of great significance for the practical reinforcement application of the PUR system with CFRP in bridge engineering.

Research on time-varying degradation of RC buildings coupled environmental effects and corrosion-induced damage from multi-scale

Corrosion of steel reinforcement in reinforced concrete (RC) buildings is influenced by several factors, including oxygen content, chloride ion diffusion, concrete damage, and humidity. A numerical method is presented to evaluate the long-term structural performance of RC buildings under environmental conditions, which takes into account the impact of steel corrosion-induced damage from multi-scale. The macro-index used for calculation is the level of reinforcement corrosion-induced damage, which considers the inter-connected effects of oxygen content, chloride ion, moisture transport, mechanical stresses, and corrosion uncertainties. In the case of RC beams, corrosion tends to occur more severely on the outer edge near concrete surface. When the corrosion factor is taken as 1.0, the calculated compression side corrosion rate of RC beam agrees well with experimental results. Due to the influence of multiple factors, the corrosion of tension-side reinforcement exhibits some degree of variability. Furthermore, the corrosion of tension-side longitudinal reinforcement in RC beams gradually intensifies from beam ends towards mid-span, with corrosion at mid-span being particularly significant. The relationship between corrosion rate and corrosion time obtained from tests falls within the range of calculation results, and the calculated results from micro-scale align favorably with tests conducted to measure crack width.

Slab Reinforcement Contributions to Negative Moment Strength of Reinforced Concrete T-Beam with High Strength Steel at Exterior Beam-Column Joints

Previous studies have revealed that the contribution of slab reinforcement to the T-beam flexural strength in negative moment regions are not negligible for the seismic capacity design. An effective slab width (i.e., effective width of flanged section) has been proposed, within which the slab reinforcement needs to be included in the calculation of the beam nominal flexural strength in negative moment regions. These studies mainly focused on the cases using normal-strength steel in moment resisting frames. However, recently high-strength steel has been widely used in reinforced concrete moment resisting frames in high seismic regions to avoid congestion near beam-column joints. The use of high-strength steel may affect the beam stiffness due to the fact that it will require less amount of reinforcement, and result in a different normal stress distribution compared to the case with normal-strength steel. Therefore, this paper investigates the slab reinforcement contribution to the flexural strength of the reinforced concrete T-beam designed with high-strength steel in negative moment regions at exterior beam-column joints, for which nonlinear pushover analyses were conducted. Beam reinforcement grade was considered as a primary parameter with several other design variables including slab thickness, height, and span length of the beam. Analytical results show that the use of high-strength steel can result in a wider effective slab width than the case of normal-strength steel for calculating the beam nominal flexural strength under the negative moment. Based on these results, new design equations were proposed.

Flexural Characterization of Concrete Beams Reinforced with 3D-Printed Formworks

3D printing has been on the rise in recent times and the civil engineering industry has adopted this technology due to its various advantages. However, printing is largely restricted to concrete members while the reinforcement is introduced manually. The current work looks at the possibility of using 3D printed thermoplastics as formwork and reinforcement for concrete beams. Three different polymeric materials, namely PETG, PLA, and TPU were utilized in this research to fabricate formwork-like reinforcement for 150×150×500 mm concrete beams. The reinforcements were 3D-printed using a fused deposition modelling (FDM) printer in the shape of a formwork to serve as moulds and external reinforcement. The reinforcing formwork geometry was designed with trapezoidal corrugations to ensure strong bonding with the concrete. The beams were tested in four-point bending configuration, and their flexural behaviour was characterized and compared with plain and steel reinforced concrete (RC) reference beams. Results indicate that all 3D printed beams reached a load capacity of around 30 kN. The post-peak behaviour of these beams was dependent on the type of polymer used. The PLA and TPU reinforced beams exhibit large post-peak deflection however their load carrying capacity was compromised, while the PETG exhibited a strain hardening behaviour but with much lower deflections. Overall, the results indicate that 3D-printed thermoplastics are a promising economical alternative to the conventional steel reinforcement.

PERENCANAAN GEDUNG RAWAT INAP RS MM DUNDA MENGUNAKAN SOFTWARE SAP 2000

This research aims to analyze the structural analysis of a building using software Since computerization is used to complete every building plan or design, the development of technology and information, especially computerization in the world of construction, cannot be separated anymore and is not a new phenomenon. The decision to use a computer to complete construction plans was based on the fact that computers have the advantage of not only being able to finish quickly but also having accuracy, effectiveness, and ease of use (Dwi Deshariyanto, Anita Intan Nura Diana 2021). The following findings have been achieved based on the final results of the development of this final report. using the SAP 2000 version 22 program to calculate reinforcement in columns, beams, and floor slabs, Using earthquake response spectrum design analysis, earthquake load calculations refer to SNI 1726: 2019 (Procedures for Planning Earthquake Resistance for Buildings and Non-Buildings), The design of this building is based on the type of reinforced concrete structure and the Unique Moment Resisting Frame System (SRPMK). The floor difference is in accordance with the relevant SNI criteria

ANALISIS PERHITUNGAN SISA TULANGAN (WASTE), KEBUTUHAN SERTA BIAYA TULANGAN PADA PROYEK RUMAH SAKIT BUNDA THAMRIN MEDAN

In the implementation of construction, there is such thing as a residual use of material which is commonly referred to as Waste Construction. Errors in the supervision and calculation of materials can have a major impact on the budget spent on project implementation, one of which is the use of reinforcing iron material. The use of reinforcing iron material is very important to be considered and calculated carefully and precisely so that it has very little material remnants. Therefore, the purpose of this research is to find out the amount of reinforcement needed and the required cost along with the reinforcement waste. The method used in this calculation is the Bar Bending Schedule method with the Microsoft Excel program to calculate reinforcement waste and calculate reinforcement requirements for column, beam and floor slab structure work along with the percentage comparison between reinforcement waste and reinforcement requirements. Based on the results of data processing, the need for reinforcement needed for the work of Foundations, Columns, Beams, Floor Plates and Stairs is 183380.233 kg. A lot of waste reinforcement for the work of Foundations, Columns, Beams, Floor Plates and Stairs as much as 26673.281 kg. The percentage of waste reinforcement for Foundations, Columns, Beams, Floor Plates and Stairs is 12.52% and the total cost required is Rp. 2,887,099,791.84.

Interaction Strength of Hanger and Horizontal Steel Reinforcement of Dapped End Beams

The dapped end beam members have a special end with low depth at the support area, which results in a weak area against shear stresses. Classical structural analysis doesn’t capture the precise steel reinforcement interaction at the dapped zone area. The main objectives of this study are to investigate the strength of the dapped end area and to analyze stresses in the steel reinforcement to evaluate the shear failure mechanism at the re-entrant corner. The experimental tests conducted on RC beam samples, in addition to the numerical simulation of these samples by a finite element program, have been compared with a mathematical model. The experimental program highlighted the strains in the steel reinforcement in the dapped region to calculate the magnitude of the stresses in the steel reinforcement. In the experimental program, six dapped beams were fabricated with a length of 3 m, a width of 150 mm, and a depth of 300 mm. The notched end has a 150-mm depth and 150-mm height. These beams were loaded by a concentrated load near support to investigate the shear strength capacity. From the results for steel reinforcement strain, it is found that hanger and horizontal steel reinforcements interact to provide dapped end shear strength. The study proposes a new approach to computing shear strength capacity at the re-entrant corner by adding the contributions of the horizontal and hanger steel reinforcement using an appropriate proportion strain factor. This method revealed greater carrying capacity for the dapped end beam compared with other common structural methods. The results of the numerical analysis were done by the ABAQUS finite element program, showing the same behavior as the experimental work. This study proved the common contribution of hanger and horizontal re-entrant corner steel reinforcement and proposed a new formula to determine the updated nominal shear strength. Doi: 10.28991/CEJ-2023-09-12-015 Full Text: PDF

Numerical Investigation on the Natural Frequency of RC Slab Reinforced with Cambered Steel Beam for Reducing Heavy-Weight Impact Noise

In an apartment building, inter-floor noise occurs due to the residents' movements. The floor impact noises are divided into light and heavy-weight impact sounds depending on the impact source. This study proposed cambered steel beam reinforcement technology installed under floor slab to reduce heavy-weight impact noise. The beam for stiffness reinforcement is supported by both side of the walls in the ceiling structure, and it reduces inter-floor noise by applying upward force to the bottom surface of the slab and controlling the slab vibration characteristics. In order to verify the effectiveness of the proposed technology and investigate the natural frequency of the floor, finite element analysis model was developed for the 84m2 type apartment plan with bearing wall structure. From the eigenvalue analysis, it is known that the first natural frequency increased by 0.37~12.67% depending on the cross-section size of the cambered steel beam. Based on the first natural frequency, as a result of evaluating the vibration standards of residential buildings presented in DIN 4150-2, the vibration characteristics of the slab were improved by reducing the vibration value KB by up to 75.20%. Therefore, this study indicated that in an apartment building reinforced with cambered steel beams, inter-floor noise caused by heavy-weight impact sound was reduced.

A Study on the Flexural Performance of Para-aramid Fiber Reinforced Concrete Beams with Recycled Coarse Aggregates

This study aims to investigate the effectiveness of para-aramid fiber sheet in enhancing the flexural performance of reinforced concrete (RC) beams made with Environmental-Friendly Recycled Coarse Aggregates. The experimental program examines the effect of substitution ratio of recycled aggregates (0%, 30%, and 50%), type of para-aramid fiber sheet (KN 206 RFL and KN AA070-RFL), and the method of fiber sheet attachment (bottom and bottom-side). The test results show that the ultimate load-carrying capacity of RC beams reinforced with para-aramid fiber sheet attached to the bottom and side parts increased by 23.9% compared to the unreinforced specimens. The main findings of the study include the identification of the BU-type attachment method as the most effective method for enhancing the flexural performance of reinforced concrete beams. The comparison of the experimental results with analytical predictions showed that the nominal flexural strength obtained from the experimental study was lower than the analytical predictions, but the ductile capacity of the specimens indicated the effectiveness of para-aramid fiber sheet reinforcement in EFRCA RC beams for flexural strength. The study highlights the potential of using para-aramid fiber sheet in improving the flexural behavior of RC beams made with recycled aggregates, offering a sustainable solution for the construction industry.

Alternate load path behaviour in structures with non-symmetrical design under column missing scenario

In the design and assessment of reinforced concrete (RC) structure against progressive collapse via single column removal scenario, also known as “alternate load path method”, development of secondary mechanisms, i.e. compressive arch action (CAA) and catenary action (CA) in double-span beams has been investigated and identified in many previous researches. The majority of the experimental tests are conducted on symmetrical double-span beams (identical span length and reinforcement detailing at both beam span). However, variations in details of beams adjacent to one another are not uncommon in RC building designs and constructions. Hence, a research study (as presented in this paper) with total of 5 RC frame tests are conducted to investigate the development of secondary mechanisms (CAA and CA) in a double-span beam with unsymmetrical 1) span length and 2) beam detailing. For each unsymmetrical case (span length and beam detailing), there will be 1 unsymmetrical double-span beam, and 2 symmetrical double-span beams (each representing one side of the unsymmetrical double-span beam) to serve as reference for quantifying the development of secondary mechanism in unsymmetrical double-span beams. The behaviour and development of secondary mechanisms are thoroughly analysed based on test observation, measured forces and displacements, etc.

Comparing the efficiency of strengthening timber beams reinforced with carbon composite rods and plates

This study reports the results of experiments comparing the effect of structural reinforcement for timber beams strengthened with different carbon composite materials. Samples of one series were strengthened by gluing a carbon fiber plate from the outside to the face of the beam. The samples of the other series were strengthened by laterally gluing two carbon fiber rods inside the beam. According to the bending research program, the ultimate loads and deflections were determined for both series. As a result of the analysis of the results and comparison with unreinforced samples from the control series, the effect of beam reinforcement and the model of their destruction were determined. Studies have shown that the effect of external reinforcement with a plate was 86.7 % according to the criterion of full failure load, 20.5 % according to the criterion of ultimate load, 13.4 % according to the criterion of ultimate deflection. The effect of rod reinforcement was 48.6 %, 18.6 %, and 4.1 %, respectively. The theoretical analysis of the results showed a convergence of up to 8.2 % with the experimental results. External reinforcement with a plate compared to lateral gluing of rods showed better results due to the placement of the plate in the zone of maximum tensile stresses. This arrangement more effectively limited the spread of ultimate stresses and the development of cracks. The reinforcement parameters of the samples (materials, placement, percentage of reinforcement) were selected under the condition of the same theoretically predicted bearing capacity after reinforcement. However, comparative experimental studies have revealed differences in the processes of deformation and destruction of reinforced beams. The results will contribute to making rational project decisions and for choosing a relevant technique of strengthening timber beams with carbon composite materials

Influence of the Oriented Configuration of the BarChip Fibre Polypropylene to the Ductility Factor of the Reinforced Concrete Beam

Abstract
 Bending and shear strength of fiber reinforced polimer concrete beams was studied in this research project. The reinforced concrete beam behaves in brittle structure in the certain reinforcement configuration. BarChip fibre polypropylene as the material for enhancement of the ductility factor is applied to the concrete beam. Three types of BarChip fibre configuration were examined: randomly spreading, placing at the mid-span area, and concentration on the tension zone. The experimental program included five beam specimens. Two of the beams were control specimens in which one was reinforced with no fibre, while the other one did not have any Barchips polypropylene. Each one of the other three specimens was reinforced with one of the above mentioned fibers by 0,4% volumetric ratio. Investigating the following issues for medium-high concrete strength was the goal of this study. In order to determine whether adding 0.4% volumetric ratio of polypropylenes as additional bar reinforcement in beams would provide adequate strength and stiffness properties comparable to reinforcing steel used as minimum bar reinforcement, it was necessary to first assess the effectiveness of each type of oriented fiber configuration on the bending strength, then to look into each beam's bending strength, shear strength, toughness, crack patterns, and near ultimate load crack width. The findings demonstrated that the bending capacity of the beam specimens was raised by all three types of polypropylene configuration more than by the beam reinforced with the fewest amount of bar reinforcement. Additionally, some of the employed fibers may cause failures other than pure shear. It is reccomended to spread the polypropylene within the tension zone of the reinforced concrete beam on the bottom mid span.
 Keywords: Fibrous Concrete, Polypropylene, Ductility, Reinforced, Beam

Analytic Investigation of Hooked Stirrups on Seismic Behavior of Reinforced Concrete 3D Frame Buildings

Ensuring the safety and stability of buildings during earthquakes is of utmost importance. This can be achieved by assessing the seismic performance of reinforced concrete structures with consideration of design details. This study focused on the seismic behavior of reinforced concrete buildings by comparing the effects of two different types of stirrups, namely those with a 135° angled end-hook shape and straight hooks, with variation of concrete strength. Pushover analysis of a sample building was performed to determine the effect of hook shape on stirrup reinforcement with a constant volumetric ratio for various concrete strength classes. The results of the analysis indicated significant differences in concrete strength and seismic behavior between the two stirrup configurations. The hooked stirrups demonstrated superior energy dissipation capability and ductility, which led to better seismic performance compared to unhooked stirrups across varying levels of concrete strength. To extend the investigation, the study compared the Mander et al., Kent–Scott–Park, and Kappos–Konstantinidis concrete models with different concrete classes (C50-C25-C20-C16-C10). The findings emphasized the importance of stirrup configuration in the design of earthquake-resistant structures. The study concluded that RC structural performance with the 135-degree hooked concrete members exhibited much better behavior of the 90-degree members for the various concrete strength. In this way, it has been revealed the arrangement and detailing of reinforcement in the construction beams and columns improves the governing effect on seismic structural performance.

Experimental Investigation of Beams Reinforced with Carbon 2D-Netzgitterträger Reinforcement

The increasing popularity of carbon-reinforced concrete (CRC) is attributed to its exceptional tensile properties, low density, no corrosion phenomenon, and remarkable flexibility, allowing it to be easily shaped into various forms. However, there is a pressing need to explore this innovative and sustainable alternative to traditional steel reinforcement. This motivates research and investigation of the feasibility of using a special 2D Netzgitterträger (NetzGT) reinforcement system, featuring a net-shaped fabricated textile made of multiple diagonally offset rovings with overlapping edge strands, as a viable alternative to traditional steel reinforcement in concrete beams. This 2D NetzGT reinforcement system has also been transformed into a 3D configuration for the development of a hollow core slab system. It is manufactured from carbon rovings with three different diagonal angles of 50°, 60°, and 70°. Laboratory experiments were conducted to assess the mechanical behavior of beams reinforced with the 2D NetzGT reinforcement. Tensile tests on strands were also performed with an increasing number of overlapped rovings to analyze their tensile strength. Additionally, single yarn pull-out tests were also conducted to examine the influence of the roving angle on the bond strength between the carbon textile roving and the concrete matrix.

Experimental and theoretical investigation of the structural behavior of reinforced glulam wooden members by NSM steel bars and shear reinforcement CFRP sheet

Abstract Reinforcing the wooden structural members is considered as a challenging matter to overcome the drawbacks of using wood in the construction field. The current investigation, therefore, presents an attempt to evaluate the effectiveness of utilizing steel bars as reinforcements in glulam timber beams using the near-surface-mounted (NSM) technique in conjunction with carbon fiber-reinforced polymer (CFRP) sheet wraps. A series of flexural testing was carried out until failure for both reinforced and unreinforced glulam members in a simple support system. Eleven specimens were examined in two groups to compare them with the control beam. Five reinforced glulam (RG) beams of the first group were reinforced with different schemes at tension and compression zones using the same bar size. The other five specimens of the second group were reinforced with shear reinforcement using fully wrapped strips made of CFRP sheet in addition to the same flexural reinforcement schemes as the first group. Each glulam beam has a span of 1.35 m and a rectangular section sized 85 mm × 175 mm. Based on experimental outcomes, theoretic modeling was provided to estimate the ultimate load capacity and bending rigidity of reinforcing glulam members. Though several theoretical predictions of flexural capacity were overstated when compared to experimental predictions, these disparities were frequently about 10%, confirming that the proposed theoretical model was accurate, and the mean of ultimate loading capacity and deflection between experimental and theoretical results were 1.01 and 1.09, respectively. Experimental results presented show that the RG beams performed much better than the unreinforced reference beams in terms of structural behavior, with improvements in ultimate load capacity ranging from 16 to 49%. On the other hand, the shear reinforcement for RG members slightly improved flexural performance, and the ultimate load capacity increased by 2–7%. Therefore, it was concluded that the NSM techniques using ordinary steel bars were effective ways in strengthening the glulam members in terms of flexural stiffness with increasing ultimate load capacity.

Postfire performance of pultruded wood-cored GFRP sandwich beams

Wood-cored sandwich components have been extensively used in constructions of buildings and bridges. However, the existing studies on the postfire behavior of these components are very limited. This study aims to quantitatively evaluate the postfire residual properties of the pultruded wood-cored GFRP sandwich (PWGS) beams. This paper mainly comprises three parts: (i) review of fire experiment of the PWGS beams; (ii) postfire bending experiments conducted on the PWGS beams with different fire scenarios and (iii) numerical study on thermal and postfire thermomechanical responses. It was found the failure modes mainly depended on the number of exposed sides and the fire damage degree. For the three-sided fire-exposed specimens (except for the one with a 25 mm-thick calcium silica board), the progressive tension rapture of the charred fibers was the dominant failure mode. The other specimens, however, exhibited the brittle in-plane shear failure of the web. Moreover, after cooling down from 250 °C to 20 °C, the GFRP and wood exhibited 68 % and 35 % of recoveries of elastic modulus respectively. A three-dimensional thermal model with kinetic thermophysical sub-models considering heat transfer, water evaporation and decomposition was developed. The developed thermal model accurately predicted the temperature responses and charring profiles. Furthermore, a thermomechanical model considering the material damage was developed to accurately predict the elastic modulus distribution, postfire residual bending capacity and failure modes. This study provides the basis for the retrofit and the reinforcement of the fire-damaged PWGS beams. In the future, study on the fire resistance of the PWGS components in fire will be required.