PSI - Issue 70

Blessy Grant C J et al. / Procedia Structural Integrity 70 (2025) 247–254

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The primary objectives of the research are provided below: • To Evaluate the structural behavior of Laced Reinforced Concrete Beams and to Assess and compare the performance of Laced Reinforced Concrete (LRC) beams with 45 0 and 60 0 lacing configurations under reverse cyclic loading. • To Compare with Conventional Concrete Beams: Analyze and compare the performance of the LRC beam specimens against conventional concrete beams in terms of key structural parameters. • To Analyze Ductility Factor: Determine and compare the ductility factors of the LRC beams with different lacing angles and conventional concrete beams to assess their deformation capacity. • To Assess Load-Deformation Characteristics: Evaluate and compare the load-deformation curves of the LRC beams with 45 0 and 60 0 lacing, and conventional concrete beams to understand their response under cyclic loads. • To Evaluate Stiffness and Energy Absorption Capacity: Measure and compare the stiffness and energy absorption capacities of the LRC beams and conventional concrete beams to gauge their effectiveness in withstanding dynamic loading. OPC 53 grade cement is utilized for all concrete mixes as per IS 12269: 2013. Coarse aggregates were procured from local crusher unit. Fineness modulus of 20 mm coarse aggregate is found to be 7.09. The sand utilized in the experiment was obtained locally and conforms to IS:383-2016 zone II grading. The fineness modulus of fine aggregate is found to be 2.779. The pH value of water was 8.3. the mix design of concrete was M30. Conplast SP430 is a chloride-free, high range water reducing admixture made from Sulphonated Naphthalene Polymers is used as a superplasticizer. The mean compressive strength of concrete cubes was 31.06 N/mm2. The mean split tensile strength of concrete cylinders was 3.13 N/mm 2 . Three beam specimens were cast with different inclination of the lacings, namely 45 0 , 60 0 , and conventional beam. The beam with fixed support at one end and free at the other end was cast with a cross-sectional dimension of 300 x 300 mm and a span of 0.82 m, secured firmly at the base. For LRC 45, the lacing angle was set at 450 and for LRC 60, it was 600. RC 90 featured conventional 90-degree closed stirrups. The shear span to depth ratio for the other specimens was kept at 2.6. The vertical section of the casted specimen (Column) was placed at fixity by a hydraulic jack that was firmly attached to the mounting frame. All specimens were cast following the guidelines of IS 456:2000. The concrete mix had a compressive strength of 31.06 MPa and a tensile strength of 3.13 MPa. Steel bars adopted as reinforcements are of 12 mm diameter and about five in numbers for all specimens. 12 mm diameter lacing bars was used. The yield strength of the reinforcement is 500 MPa and a Young's modulus is 210,000 MPa.

Fig. 2. Test specimen LRC 45

In the Reverse cyclic test, a hydraulic jack is utilized to hold the vertical portion of the specimen securely and hydraulic jack is rigidly fixed to the structural frame. During the test, alternative loading and unloading are applied to the beam in the up ward and downward directions. The Load is applied at beam’s top surface using a hydraulic jack load cell (Actuator) which has its capacity of 500 kN as shown in Fig. 2. The load cell is positioned at 160mm from