Behavior of reinforced concrete column-beam joint subjected to close in blast loads with polyurea and FRP sheets

This thesis investigates the structural response of reinforced concrete (RC) column-beam joint under close-in blast loads using finite element modeling in LS-DYNA with an Arbitrary Lagrangian-Eulerian (ALE) formulation. Failure is captured through element erosion based on maximum principal strain. The study employs concrete with a compressive strength of 38.5 MPa and reinforcing steel with a yield strength of 400 MPa. Parametric analyses examined mesh-density sensitivity, explosive charge weight, blast-mitigation performance of various coatings like Poly urea and FRP Sheets. Numerical models were first validated against experimental contact-explosion tests on RC bridge columns (Yuan et al., 2017) achieving close agreement in peak accelerations and damage profiles. Complementary boundary conditions and measurement locations from related studies further improved model fidelity. Mesh convergence was confirmed at 20 mm element size (<5 % variation from finer meshes). In uncoated joints under 2 kg (4.4 lb) TNT equivalent at 0.575 m (1.89 ft.) standoff, analyses reveal localized failure zones, von Mises stresses in concrete that exceed static compressive strength, accompanied by incident and reflected pressure histories. Steel reinforcement remains largely elastic at this charge level. Application of polyurea coatings significantly reduces peak stresses (30–40 %) and suppresses spalling through viscoelastic energy dissipation. FRP sheets also show overall suppression of damage in the structure. Results demonstrate that protective coatings offer a practical strengthening strategy for enhancing survivability of critical RC infrastructure under extreme dynamic loads. Additional parametric studies were also carried out by increasing the TNT charge weight and the coating thickness to examine the sensitivity of structural damage to blast intensity and to assess the effectiveness of thicker coatings in enhancing blast protection. This work contributes quantitative insights and validated modeling parameters to blast-resistant design guidelines for column-beam joints in high-risk structures.

Name thesis:degree_name

M.S. (Master of Science)

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Civil Engineering (UMKC)

Grantor

University of Missouri--Kansas City

Year dc:date.issued

2026

Author dc:creator

• Adhikari, Apurba

Advisor dc:contributor.advisor

• Ganesh, Thiagarajan

Language dc:language.iso

en_US

Handle dc:identifier.uri

https://hdl.handle.net/10355/112347

OAI identifier oai:identifier

oai:mospace.umsystem.edu:10355/112347