Research Interest
Sustainable Construction Materials - UHPC, ECC, FRC, and TRC
Flexure, and Shear Behavior of Bridges Girders [Bridge Engineering]
Condition Assessment of Existing Structures Using the Acoustic Emission Technique and NDT techniques
Fire Performance of Concrete Structures
Fatigue Behavior of Railway Sleepers and Structural Optimization
Research Projects
Postdoctoral Research Fellowships: https://doi.org/10.69777/363881
Title: Development of a comprehensive compressive stress-strain model and a simplified stress block approach for flexural design of UHPFRC
Abstract: Ultra-High Performance Fiber Reinforced Concrete (UHPC) offers exceptional compressive strength (>120 MPa) and high toughness due to its low porosity and fiber reinforcement. Unlike conventional concrete, UHPC columns exhibit negligible bursting under combined flexural and compressive loads, thus improving their seismic performance. Although structural-level studies highlight the superior compressive toughness of UHPC, there is no comprehensive material model capturing its entire compressive stress-strain behavior, particularly its post-peak response. Current studies using uniaxial compression tests only capture the pre-peak behavior, often resulting in explosive failure after the maximum strength due to the uniform deformation across the entire cross-section. This project aims to fill this gap by conducting 14 eccentric compression tests on full-scale UHPC specimens using the Hognestad method to evaluate its compressive behavior and develop practical design guidance, including a compression material model and stress block parameters for flexural design. The study will explore variables such as four commercially available UHPC materials, transverse reinforcement ratios (0% and 1%), fiber volumes (1% and 2%), and compressive zone depths (4, 8, and 12 inches) to cover typical beam and column conditions. The results will expand UHPC design codes by providing models of pre- and post-peak behavior, unlike current guidelines that focus only on pre-peak behavior. A comprehensive compressive model will enable the use of higher reinforcement ratios in UHPC beams, thereby reducing cross-sectional areas, self-weight, material usage, and carbon footprint, promoting more sustainable concrete structures. This research is essential for the flexural design section of the future UHPC Annex of CSA S6 and the ACI-239-0C Structural Design Guidelines for UHPC.
Funding: $90,000 CAD
Status: Ongoing
Ultra-High Performance Fiber Reinforced Concrete - UHPFRC or UHPC
Developed Ultra-High Performance Concrete (UHPC) using locally available materials in India. Utilizing the close particle packing approach, a UHPC mix was also designed in the USA during my Fulbright program at Iowa State University, earning Second Place in the Mix Design Competition at the Third International Interactive Symposium on UHPC.
Posters on UHPFRC for GPSS-ISU conference
The utilization of ultra-high performance fiber-reinforced concrete (UHPFRC) in the construction industry is growing quickly because of its exceptional mechanical and durability characteristics. However, the high initial cost of the UHPC mix restricts its implementation in many areas. Therefore, it is crucial to develop non-proprietary UHPC to reduce the cost. Though several studies in the past have focused on UHPFRC girders, understanding web reinforcement requirements in the case of a 2% fiber-reinforced specimen needs to be understood. Similarly, reducing fiber to 1% volume fraction reduces cost and the web reinforcement requirement in this case. To address these questions, eight post-tensioned I-shaped UHPFRC girders are tested at a span-to-depth ratio of 1.6 to evaluate the minimum web shear reinforcement requirements. The parameters of this study include (i) volume fraction of fibers (1% and 2%), (ii) type of fibers (Straight, combination of hooked and straight), and (iii) minimum web shear reinforcement ratio of 0.3% and 0.6%. Experimental findings indicate that UHPFRC girders tested at low a/d ratios do not require minimum web shear reinforcement for enhancing strength. However, a minimum web reinforcement is necessary for crack-opening resistance at service loads. Per existing code recommendations, the serviceable load limits are between 30% and 40% of their ultimate load. Adding 0.6% web shear reinforcement and 1.0% hybrid fibers can reduce the crack opening at the ultimate load from 2.9 mm to 1.4 mm. However, reducing the fiber volume fraction from 2.0% to 1.0% decreases the ultimate load and increases crack opening at the ultimate. Girders reinforced with a minimum volume fraction of 1.0% and web shear reinforcement ratios of 0.3% and 0.6% were compared to girders with 2.0% of steel fibers. Experimental results show that girders with 1.0% hybrid fibers and web shear reinforcement ratio of 0.6% performed similarly to ones reinforced with straight steel fibers of 2% Vf. Measurement of principal compression and tensile strains of all tested beams confirmed that they failed in shear tension mode.
PCI Big-Beam competition 2023 as a part of the Iowa State University Cyclone Big Beamer Team
Explored UHPC applications in defence applications. This research is in progress to obtain optimum design for blast and bullet penetration resistance.
Fiber Reinforced Concrete (FRC)
Flexure and Shear Behavior of FRC Prestressed Beams
Poster Presentation on Role of Hybrid Fibres in Crack Arresting Mechanism of Notched Beams presented at IIT Madras
Fire Performance of Concrete Structures: Hollow Core Slabs
Structural Health Monitoring using Acoustic Emission Technique & DIC techniques
Shear Behavior of Self-Compacting Fiber Reinforced Concrete Deep Beams
The shear behavior of reinforced concrete deep beams made of self-compacting concrete with different volume fractions of discrete macro steel fibers (0.5%,1.0%, and 1.5%) is studied. All the beams are tested at shear span to depth ratio of 1.0, and the effect of loading plate width on shear carrying capacity is also studied. Similarly, the effectiveness of steel fibers in improving the shear behavior is compared with the beams made of plain concrete and the beams with 0.3% web reinforcement in both horizontal and vertical directions. Test results revealed that the addition of macro steel fibers significantly improved the performance of deep beams, particularly first cracking load, ultimate shear capacity, ultimate deformation, and ductility. However, the addition of steel fiber more than 1.0% volume fraction did not increase the ultimate shear capacity. A simplified analytical model is proposed to predict the ultimate shear capacity of steel fiber reinforced concrete deep beams. The existing cracking strut and tie method (CSTM) is extended to include the effect of fibers, and a simplified fiber-reinforced cracking strut and tie method (FR-CSTM) is proposed. Predictions of FR-CSTM are compared with CSTM and two-parameter kinematic theory (2PKT). The comparisons of predictions with test results and existing models show that the proposed method can capture the ultimate shear capacity of deep beams with reasonable accuracy.
Anchorages in Concrete Construction
Research interests include:
Anchorage or fastenings in concrete construction refers to the means to connect a structural or non-structural component to a concrete structure. The anchorage is used to transmit the loads applied to a structural or non-structural component inside the concrete member. Anchorages are typically two different types: Cast-In systems and Post-installed systems. The cast-in system is installed by securing it in a pre-defined location inside the formwork and cast into the concrete. Post-installed anchorages offer a versatile solution to the problem of anchoring in hard concrete, which typically consists of drilling a hole in the concrete member and installing the anchor. Typical load-transfer mechanisms utilized by post-installed anchors include mechanical interlock, bond, and friction (also in combination).
Research Publications
Journal Papers
12. C. Lakavath and S. S. Prakash, “Influence of fiber dosage, fiber type, and level of prestressing on the shear behaviour of UHPFRC I-girders,” Engineering Structures (Q1), vol. 300, p. 117 146, 2024, issn: 0141-0296. doi: https://doi.org/10.1016/j.engstruct.2023.117146.
11. C. Lakavath and S. S. Prakash, “Interface shear behavior of ultrahigh-performance fiber-reinforced concrete using digital image correlation technique,” Journal of Materials in Civil Engineering (Q1), vol. 36, no. 3,p. 04 023 589, 2024. doi: 10.1061/JMCEE7.MTENG-16817
10. C. Lakavath and S. S. Prakash, “Tensile constitutive relationship of UHPFRC from crack hinge based inverse analysis of notched beams,” Engineering Structures (Q1), vol. 318, p. 118 698, 2024, issn: 0141-0296. doi: https://doi.org/10.1016/j.engstruct.2024.118698.
9. C. Lakavath, S. S. Prakash, and S. Allena, “Tensile characteristics of ultra-high-performance fibre-reinforced concrete with and without longitudinal steel rebars,” Magazine of Concrete Research (Q2), vol. 76, no. 13, pp. 738–754, 2024. doi: 10.1680/jmacr.23.00181.
8. C. Lakavath, A. B. Bhosale, S. S. Prakash, and A. Sharma, “Effectiveness of hybrid fibers on the fracture and shear behavior of prestressed concrete beams,” Fibers (Q2) (Invited article), vol. 10, no. 3, 2022, issn: 2079-6439. doi: 10.3390/fib10030026.
7. M. S. V. Sagi, C. Lakavath, and S. S. Prakash, “Effect of steel fibers on the shear behavior of self-compacting reinforced concrete deep beams: An experimental investigation and analytical model,” Engineering Structures (Q1), vol. 269, p. 114 802, 2022, issn: 0141-0296. doi: https://doi.org/10.1016/j.engstruct.2022.114802.
6. C. Lakavath, M. S. V. Sagi, S. S. Joshi, and S. S. Prakash, “Finite element studies on the flexure-shear behavior of steel and hybrid fiber reinforced prestressed concrete beams,” Indian Concrete Journal (Q3) (Invited article), vol. 95, no. 1, pp. 58–70, 2021.
5. C. Lakavath, S. Suriya Prakash, and S. Dirar, “Experimental and numerical studies on shear behaviour of macro-synthetic fibre reinforced prestressed concrete beams,” Construction and Building Materials (Q1), vol. 291, p. 123 313, 2021, issn: 0950-0618. doi: https://doi.org/10.1016/j.conbuildmat.2021.123313.
4. M. S. V. Sagi, C. Lakavath, S. S. Prakash, and A. Sharma, “Experimental study on evaluation of replacing minimum web reinforcement with discrete fibers in rc deep beams,” Fibers (Q2) (Invited article), vol. 9, no. 11, 2021, issn: 2079-6439. doi: 10.3390/fib9110073.
3. S. Sahoo, C. Lakavath, and S. S. Prakash, “Experimental and analytical studies on fracture behavior of fiber-reinforced structural lightweight aggregate concrete,” Journal of Materials in Civil Engineering (Q1), vol. 33, no. 5, p. 04 021 074, 2021. doi: 10.1061/(ASCE)MT.1943-5533.0003680.
2. A. B. Bhosale, C. Lakavath, and S. Suriya Prakash, “Multi-linear tensile stress-crack width relationships for hybrid fibre reinforced concrete using inverse analysis and digital image correlation,” Engineering Structures (Q1), vol. 225, p. 111 275, 2020, issn: 0141-0296. doi: https://doi.org/10.1016/j.engstruct.2020.111275.
1. C. Lakavath, S. S. Joshi, and S. S. Prakash, “Investigation of the effect of steel fibers on the shear crack-opening and crack-slip behavior of prestressed concrete beams using digital image correlation,” Engineering Structures (Q1), vol. 193, pp. 28–42, 2019, issn: 0141-0296. doi: https://doi.org/10.1016/j.engstruct.2019.05.030
Patents
1. Lakavath C., SS Prakash, S. RanjithkumarA, S.Allena, 2023. Method to Produce an Ultra-High-Performance Fiber-Reinforced Concrete. Indian Patent, Application No: 202341004954 A, Date of Filing: 25/01/2023, and Date of Publication: 26/07/2024
Book chapters
2. Lakavath, C., Bhosale, A. and Prakash, S.S., 2020. Experimental Investigation on Crack-Arresting Mechanism of Steel Fibre-Reinforced Concrete Prism Specimens Using DIC and AE Techniques. In Advances in Structural Engineering (pp. 51-65). Springer, Singapore.
1. Lakavath, C., Allam, R., & Kondraivendhan, B. (2019). Experimental and Numerical Studies on the Behaviour of Broad-Gauge Railway Sleepers in Static Bending Condition. In Sustainable Construction and Building Materials (pp. 781-792). Springer, Singapore.
International Conferences
8. C. Lakavath, S. S. Prakash, A. Bambole, and G. Rai, “A case study on proof load test of distressed reinforced concrete flyover bridge,” in CARRS2023 at the Indian Institute of Technology Hyderabad – India, 2024.
7. S. Pradumn B, C. Lakavath, and S. S. Prakash, “Simplified analytical approach for predicting the moment-curvature behavior of uhpc girders under flexure,” in CONSEC-IIT Madras, 2024.
6. C. Lakavath, M. Singh, and S. S. Prakash, “Classifying failure modes of ultra-high-performance fiber reinforced concrete fracture beams using acoustic emission technique,” in IABSE Congress: Engineering for Sustainable Development, New Delhi, India, 20-22 September 2023, Springer, 2023, pp. 1554–1560. doi: 10.2749/newdelhi.2023.1554.
5. C. Lakavath and S. S. Prakash, “Numerical study on shear behavior of uhpc concrete beams,” in 76th RILEM week at the University of Kyoto - Japan, 2022.
4. M. S. V. Sagi, C. Lakavath, and S. S. Prakash, “Numerical investigation on evaluation of minimum web-reinforcement provisions for shear design of rc deep beams,” in 17WCEE -17th WORLD CONFERENCE ON EARTHQUAKE ENGINEERINGAt: Japan, 2021.
3. C. Lakavath, A. Bhosale, and S. S. Prakash, “Experimental investigation on crack-arresting mechanism of steel fibre-reinforced concrete prism specimens using dic and ae techniques,” in Advances in Structural Engineering, K. V. L. Subramaniam and M. A. Khan, Eds., Singapore: Springer Singapore, 2020, pp. 51–65, isbn: 978-981-15-4079-0.
2. C. Lakavath, R. Allam, and B. Kondraivendhan, “Experimental and numerical studies on the behaviour of broad-gauge railway sleepers in static bending condition,” in Sustainable Construction and Building Materials: Select Proceedings of ICSCBM 2018, Springer, 2019, pp. 781–792.
1. C. Lakavath, V. Pidapa, S. S. Joshi, et al., “Shear behavior of steel fiber reinforced precast prestressed concrete beams,” 2018
Poster Presentations
2. Lakavath,C., Sagi, M.S.V., & Prakash,S.S. (2021). Effect of Steel Vs Macro-Synthetic Fiber on Shear Behavior of Reinforced Concrete Deep Beams' 75th RILEM Conference.
1. Lakavath C, & Prakash SS., 2019 “Role of Hybrid Fibres in Crack Arresting Mechanism of Notched Beams” 5th CRI Symposium at IIT Madras (Sep 14th,2019).
Awards
Best Ph.D. thesis award by Indian Concrete Institute (ICI) - Best Ph.D. Thesis in Concrete Award.
Award of excellence in recognition as the overall third-place winner of the Engineering Student Design (Big Beam) Competition by PCI.
Award of excellence in recognition as the overall second-place winner of the UHPC student Competition- Third international interactive symposium on UHPC.
RILEM best student poster award at the 75th RILEM Annual Week on 'Effect of Steel Vs Macro-Synthetic Fiber on Shear behaviour of Reinforced Concrete Deep Beams' at Universidad Autonoma de Nuevo León, Mexico.
Bagged best research work award in PG-Research presentation at INTER-IIT meet-up (CIVIL CONCLAVE 2020)-exclusive for civil engineering students organized by IIT Roorkee. (Announcement Video)
First prize in the PG-Research presentation at INTER-IIT meet-up (CIVIL conclave 2021) organized by the Indian Institute of Technology Roorkee-India
First prize in the PG-Research presentation at INTER-IIT meet-up (CIVIL conclave 2020) organized by the Indian Institute of Technology Roorkee-India
Second prize in the paper presentation at the technical fest organized by Bomma College of Engineering & Technology (Bomma premier league 2k14)
Second prize in the JUNK-YARD at the technical fest organized by JNTUH College of Engineering Manthani (aavishkruth-2K14).
First prize in the paper presentation at the technical fest organized by Sindhura College of Engineering & Technology(2k13)
First prize in the Model-making competition at the technical fest organized by JNTUH College of Engineering Manthani (aavishkruth-2K13)
Academic Collaborations