Deflection (engineering)

About: Deflection (engineering) is a research topic. Over the lifetime, 30862 publications have been published within this topic receiving 298849 citations.

Racking Deformations in Wood Shear Walls

Abstract: The theory presented in this paper predicts racking deformations in wood‐stud shear walls. The energy method employed defines the wall performance in terms of the lateral nonlinear load‐slip behavior of the nails which fasten the sheathing to the frame. Using power curves to define the nail loadslip relationship, the theory predicts that wall deformation due to nail slip will also be defined by a power curve. The theory also includes linear deformation due to shear distortion of the sheathing material, and provides accurate estimation of wall performance up to moderate load levels. The method presented should be of interest to engineers who design light frame structures, to researchers, and to those who are concerned with building codes.

Bridge Deflection Measurement Using Digital Image Correlation with Camera Movement Correction

Abstract: When displacement measurement by digital image correlation is performed in outside for the inspection of real structures, the position and the direction of a camera are often changed slightly because of wind, oscillations and the lack of stability of ground. In order to realize the bridge deflection measurement by digital image correlation, a method for correcting the effect of camera movement is proposed in this study. The relationship between images before and after the camera movement is described by an equation of perspective transformation. The unknown coefficients of the equation are determined from undeformed regions of the images. Then, the effect of the camera movement is eliminated by using the perspective transformation. The effectiveness is validated by applying the proposed method to the rigid body rotation and translation measurement of a planar specimen, the deflection measurement of a wide-flange beam, and the bridge deflection measurement. Results show that the effect of the camera movement can be corrected by the proposed method. It is emphasized that noncontact displacement measurement is possible by simple and easy procedure with digital image correlation for the structural evaluation of infrastructures. [doi:10.2320/matertrans.I-M2011843]

Corroded RC beams patch repaired and strengthened in flexure with fiber-reinforced polymer laminates

Abstract: This paper presents the experimental and analytical behavior of four reinforced concrete beams with corroded steel reinforcements with low mass loss (around 7.5%), yet in need of removal of cracked concrete cover, treatment of steel bars, application of cement-based repair patch and of externally bonded EBR or NSM FRP laminates. It comes out the assessment of residual flexural capacity of the as-built corroded beams and the suitable strengthening measures depend largely on the concrete cover crack pattern and width, as accelerated corrosion-related cracks were measured just wider than 0.3 mm (failing to fulfill serviceability limit state requirements marginally). This study also demonstrates that assessment of contribution of corroded steel and treatment in the above cases requires partial uncovering in order to apply inhibitors and better calibrate the actual mass loss with corresponding cover concrete damage. All the above may be fulfilled at the characteristic limit state of initiation of concrete cover separation. The observed failure modes, the recorded force – deflection curves and strains on steel and FRP laminates, validate for the strengthened corroded beams the full force transfer through old concrete – patch interface and through patch and FRP laminate interface, as predicted in the case of non-patched beams. The beam strengthened with two NSM FRP strips of equivalent axial rigidity with EBR FRP laminate presented 18.2% higher load and 41.6% higher deflection than the latter. The P-d behavior of all beams was modeled with advanced 3D Finite Elements (FE) that enabled further analytical investigation of the observed modes of failures and patch repair effects.