Residual post fire strength of non-prismatic perforated beams

The main aim of this study is to assess the performance and residual strength of post-fire non-prismatic reinforced concrete beams (NPRC) with and without openings. To do this, nine beams were cast and divided into three major groupings. These groups were classified based on the degrees of heating exposure temperature chosen (ambient, 400, and 700°C), with each group containing three non-prismatic beams (solid, 8 trapezoidal openings, and 8 circular openings). Experimentally, given the same beam geometry, increasing burning temperature caused degradation in NPRC beams, which was reflected in increased mid-span deflection throughout the fire exposure period and also residual deflection after cooling. But on the other hand, the issue with existing openings was exacerbated. The burned NPRC beams were then gradually cooled down by leaving them at ambient temperature in the laboratory, and the beams were loaded until failure to examine the effect of burning temperature degree on the residual ultimate load-carrying capacity of each beam by comparing them to unburned reference beams. It was found, increasing the exposure temperature leads to a reduction in ultimate strength about (5.7 and 10.84%) for solid NPRC beams exposed to 400 and 700°C, respectively related to unburned one, (21.13 -32.8) % for NPRC beams with eight trapezoidal openings, and (10.5 - 12.8) % for those having 8 circular openings. At higher loading stage the longitudinal compressive strain of Group ambient in mid-span of solid beams reach 2700 με, while the others with openings exhibit divergent strain higher than that, it’s about 3300 με meanwhile, the lower chord main reinforcements have been pass beyond yielding stress. Exposure to high temperatures reduces rafters’ stiffness causing a reduction in load carrying capacity, companion with premature failure consequently reduce the strain at the ultimate stage.

Evaluation of Static Pile Load Test Results of Ultimate Bearing Capacity by Interpreting Methods

in geotechnical engineering, foundation piles are ideal for deep foundations that cannot bear higher loads. This architectural expansion places a great deal of responsibility on the engineer to anticipate the appropriate load for the constructor. Unfortunately, calculations of the pile’s bearing capacity are not accessible. It has always been a source of concern for geotechnical engineers, as the structure’s safety depends on the pile’s bearing capacity and gives it a safe value. These research tests are previously known pile load test data from several locations in Nasiriyah to determine the ultimate load-carrying capacity using various interpreting methodologies. A database that was used to test the pile load for three different areas in Nasiriyah, southern Iraq: The Main Drain River Bridge Project, the Al-Eskan Interchange Project, and the Al-Hawra Hospital, as determined by analytical methods, as well as evaluating the final loading values resulting from the methods used, by ASTM D-1143, American and British Standard Code of Practice BS 800. The final capacity for the pile bearing is estimated using these approaches, which are depicted in the form of a graph-based on field data. Chin-Kondner and Brinch Hansen algorithms anticipate the highest failure load for all piles based on the comparison. On average, Chin–Kondner’s ultimate load is 22% higher than Hansen’s maximum load for the 22 pile load tests. Decourt and DeBeer, and Mazurkiewicz’s techniques yielded the closest average failure load. Buttler-Hoy approach yielded the smallest failure load.

Post-Fire Behavior of Non-Prismatic Beams with Multiple Rectangular Openings Monotonically Loaded

The main objective of this paper is to study the behavior of Non-Prismatic Reinforced Concrete (NPRC) beams with and without rectangular openings either when exposed to fire or not. The experimental program involves casting and testing 9 NPRC beams divided into 3 main groups. These groups were categorized according to heating temperature (ambient temperature, 400°C, and 700°C), with each group containing 3 NPRC beams (solid beams and beams with 6 and 8 trapezoidal openings). For beams with similar geometry, increasing the burning temperature results in their deterioration as reflected in their increasing mid-span deflection throughout the fire exposure period and their residual deflection after cooling. Meanwhile, the existing openings situation was compounded. The burned NPRC beams were left to gradually cool down under ambient laboratory conditions, and afterward, they were loaded until failure. The influence of temperature on the residual ultimate load-carrying capacity of each beam was studied by comparing these beams with unburned reference beams. Increasing exposure temperature reduces the ultimate strength of solid NPRC beams exposed to temperatures of 400°C and 700°C by about 5.7% and 10.84% respectively. Meanwhile, NPRC beams with trapezoidal openings showed ultimate strength reductions of 21.13% and 32.8% (for beams with 8 openings) and 28% and 34.4% (for beams with 6 openings) under the same burning conditions. The excessive mid-span deflections for these three types of beams were 2%–30.8%, 1.33%–21.8%, and 1.5%–17.4% under the same burning conditions.

Flexural Behaviour of RC Beams with a Circular Opening at the Flexural Zone and Shear Zone Strengthened Using Steel Plates

In this paper, an investigation on the behaviour of RC beams with circular openings in the flexural zone and shear zone strengthened using steel plates is presented. Totally seven beams were cast: a control beam, one beam with a circular opening of size of one-third the depth of the beam (100 mmϕ) in the flexural zone, one beam with opening strengthened using the steel plate, one beam with a circular opening of size of 100 mmϕ in the shear zone, one beam with an opening in the shear zone strengthened using the steel plate, one beam with two circular openings of size of 100 mmϕ in the shear zone, and another beam with two openings in the shear zone strengthened using the steel plate. The experiments were conducted in a loading frame of 400 kN capacity. The beams were subjected to two-point loading. The ultimate load carrying capacity reduced marginally by 1.78% and 2.8% compared to that of the control beam when a circular opening of 100 mmϕ was provided in the flexural zone and shear zone, respectively, and when the opening was strengthened with steel plates, it reduced by 3.04% and 25%, respectively, but the ductility increased when steel plates were provided. Beams with an opening of size of one-third the depth of the beam (100 mmϕ) in the flexural zone strengthened with the steel plate can be provided, as the load carrying capacity is only marginally reduced compared to the control beam, and the ductility is more when compared with beams with unstrengthened openings.

Behavior of Simply Supported Concrete Beam Using CFRP (Carbon Fiber Reinforced Polymer)

The aim of this paper is to study the behavior of beam with the use of CFRP composite by experimentally and by ANSYS and compare both the results and compare load carrying capacity. For experimentally we cast Nine no’s of beam of size 100×100×400 mm, of M30 grade of concrete and curing for 7 days and after 7 days curing we conduct UPV test and find homogeneity of concrete beam and decided carbon fiber wrapping techniques we create two set of beam with 230 GSM wrapped with double layer and two set of beam with 430 GSM wrapped with double layer and two set of beam with 430 GSM wrapped with single layer, and 3 control beams without wrapping and test for flexural strength and by this test we observe the ultimate load carrying capacity and flexural strength of carbon fiber wrapped beam is increased as compare to control beams.

Numerical Investigation of Precast Grouted Sleeve Connection under Cyclic Loading Using ABAQUS

This paper deals with numerical investigation using finite element software, ABAQUS CAE, for the analysis of precast reinforced concrete (RC) column connected to the foundation containing protruding bar in grouted sleeve subjected to axial, and lateral loads, including the cyclic loading response. The monolithic connection of column and foundation is designed and the same has been used for the design of precast concrete column and foundation. The model focusses on the length of the protruding bar provided in the foundation that is connected to the column through the grouted sleeve. As there is lack of Indian standard codes in the design of precast concrete connections, an attempt has been made by varying the length of protruding bars. The model was subjected to quasi-static loading condition and parameters such as ultimate load carrying capacity, load-displacement hysteresis, ductility and plastic strain were studied and were compared with that of monolithic connection. The results proved that when the length of protruding bars provided was equal to development length of the bar provided, the results were comparable with that of monolithic connection.

Analytical Predictions on Flexural Strengthening of Reinforced Concrete Beams with Hybrid FRP Laminate

This paper presents the predicted regression equation for the study parameters of Reinforced Concrete (RC) beams strengthened with Hybrid Fibre Reinforced Polymer (HyFRP) laminate at the soffit of beam. To study the effectiveness of HyFRP laminate on flexural strengthening a total of five beams were cast and tested.The variable parameters are thickness, elastic modulus and tensile strength of HyFRP laminates. Four combinations of HyFRP laminates precisely, 90% Glass fibre + 10% Basalt fibre of thickness, 80% Glass fibre + 20% Basalt fibre, 70% Glass fibre + 30% Basalt fibre, 60% Glass fibre + 40% Basalt fibre, and their corresponding thickness were 2.78, 3.24, 3.86 and 4.24mm respectively.The test results concluded that reinforced concrete beams strengthened with 70%Glass + 30%Basalt HyFRP laminate enhance the ultimate load carrying capacity of 68.97% with respect to control beam. The values reached through the predicted regression equation showed equitable accuracy with those of experimental values.

Impact of Length and Percent Dosage of Recycled Steel Fibers on the Mechanical Properties of Concrete

The global rapid increase in waste tyres accumulation, as well as the looming social and environmental concerns, have become major threats in recent times. The use of Recycled Steel Fiber (RSF) extracted from waste tyres in fiber reinforced concrete can be of great profitable engineering applications however the choice of suitable length and volume fractions of RSF is presently the key challenge that requires research exploration. The present experimental work aims at investigating the influence of varying lengths (7.62 and 10.16 cm) and dosages (1, 1.5, 2, 2.5, 3, 3.5, and 4%) of RSF on the various mechanical properties and durability of concrete. Test results revealed that the varying lengths and dosages of RSF significantly affect the mechanical properties of concrete. The improvements in the compressive strength, splitting tensile strength, and Modulus of Rupture (MOR) of RSF reinforced concrete observed were about 26, 70, and 63%, respectively. Moreover, the RSF reinforced concrete showed an increase of about 20 and 15% in the yield load and ultimate load-carrying capacity, respectively. The durability test results showed a greater loss in compressive strength and modulus of elasticity and a smaller loss in concrete mass of SFRC. Based on the experimental findings of this study, the optimum dosages of RSF as 2.5 and 2% for the lengths 7.62 and 10.16 cm lengths, respectively are recommended for production of structural concrete. Doi: 10.28991/cej-2021-03091750 Full Text: PDF

Improvement of Load Carrying Capacity of Concrete Pavement Slabs Using Macro Synthetic Fibers

This study presents the results of an investigation of the effect of macro synthetic fibers (MSF) reinforcement on the load carrying capacity of concrete pavement slabs. Six concrete slabs having dimensions of 800 × 800 × 50 mm3 were prepared and tested under static loads at three different positions: interior, edge and corner of the slab. Three of the slabs were Portland cement concrete (PCC) and prepared as references. The other three slabs were macro synthetic fiber reinforced concrete (MSFRC). Mechanical properties examined in this study included compressive strength, splitting tensile strength, flexural strength and modulus of elasticity and ductility of PCC and MSFRC. The findings showed that the addition of MSF to PCC improved the load carrying capacity of concrete pavement slabs. Test results obtained indicated that the ultimate load carrying capacity of MSFRC slabs was increased by 24%, 20%, and 23% for interior, edge and corner loading positions, respectively.