In this study, FEM were performed on L-shaped and T-shaped beam-column joints in order to establish a verification method for joints by the finite element analysis (FEM), and an applicability of the damage indices (the second invariant of deviation, and the strain and normalized cumulative strain energy), which have been shown to be applicable to RC beams, columns, slab members, etc., to the joint was investigated. It was confirmed that damage at corner angles was determined earlier than in other cases. The FEM indicated that the damage indices can be used to evaluate the damage to the joints because the cracking and compression damage of concrete can be generally expressed by dividing the joint into sections.

This study reports experimental investigations on reinforced concrete (RC) deep beams with web opening in the shear span to evaluate the effect of large rectangular openings on strut efficiency, shear strength, and ductility. The tested beams had dimensions of 1300 x 200 x 500 mm, with rectangular openings varying in size from 200 × 100 mm to 300 × 150 mm. The shear span-to-depth ratio (a/d) was maintained at 0.75. The beams were reinforced with 0.30% web reinforcement in each direction and 1.80% flexural tension reinforcement. The ultimate load capacities of beams with openings of 200 x 100 mm and 300 x 150 mm were 61 and 76% lower, respectively, than that of the reference beam. The ultimate load of the beam with the larger opening was 38% lower than that of the beam with the smaller opening. Horizontal web reinforcement, detailed at the upper and lower corners of the large openings, effectively mitigated the reduction in initial stiffness and ductility. The inclination of the critical strut varied with the opening size, affecting the ultimate load capacity and failure mode. An accurate prediction of the shear capacity is essential to prevent sudden failures. The strut-and-tie model for deep beams with openings located at the centre of the shear span has been simplified. Additionally, a strut efficiency factor was formulated as a function of concrete strength, considering the influence of the critical strut angle.

For large-scale infrastructure such as concrete dam, a nondestructive and non-contact testing method to estimate subsurface damages is demanded. Passive infrared thermography is effective technique to detect subsurface damages due to heat capacity in concrete. Surface temperature obtained from thermal images are affected by not only time but also weather condition, shadow effects, structural condition and internal condition. In this study, surface temperature of concrete dam is calculated by heat balance analysis and LSTM, measured and calculated values at exudation and non-damaged points are compared to evaluate thermal images. Estimation accuracy by LSTM is higher than heat balance analysis since LSTM considering shadow effect and latent heat transfer which isn’t included in heat balance analysis. These attempts are indicated to evaluate the validation of passive infrared thermography for damage detection in concrete dam.

An integrated experimental, numerical study was conducted to understand the behavior of a wide RC beam with top UHPC overlay under a four-point bending test. The experimental study was carried out to assess the influence of different overlay thickness. It showed improvement in the structural performance compared with the beam without repair. In the numerical simulation, a three-dimensional finite element modeling was carried out, and its results were matched with the experimental results. This paper focuses on crack growth and stress around cracks at the interface between normal concrete and UHPC overlay. The FEM results showed that the locations of debonding occur at the pure moment zone, and delamination at the interface is caused by different stresses acting at the same location. At the interface surface where compression stress from the reinforced concrete (RC) acts, tension stress from the UHPC overlay is also applied at the same location. Additionally, with a thinner overlay, partial delamination occurred at the interface because of the bending experienced throughout the repaired beam. Conversely, a 50 mm UHPC overlay provides sufficient stiffness to resist bending, which can lead to faster delamination over a larger area of the beam's surface.