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In order to improve the mechanical behavior of the low-temperature ${\mathrm{\text{Sn}}}_{58}\mathrm{\text{Bi}}$ (SnBi) lead-free solder joint, the ${\mathrm{\text{Sn}}}_{0.7}{\mathrm{\text{Ag}}}_{0.5}{\mathrm{\text{Cu}}}_{3.5}{\mathrm{\text{Bi}}}_{0.05}\mathrm{\text{Ni}}$ (SACBN) solder ball with the diameter of 400 $\mu$m was pre-soldered on Cu to obtain the SnBi/SACBN/Cu composite joint. The microstructure and shear behavior of the solder joints were investigated. Experimental results indicate that SnBi solder is well bonded on the SACBN bump due to the elemental diffusion and dissolution between the molten SnBi and solid SACBN bump during the soldering process. The addition of the SACBN bump shows a significant effect on the formation and growth of the $\beta$-Sn grains in the SnBi bulk. Compared with the SnBi/Cu joint, the SnBi bulk in the composite joint shows enlarged $\beta$-Sn dendritic grains. Meanwhile, the interfacial intermetallic compound (IMC) layer transforms from Cu₆Sn₅ into (Cu, Ni)₆Sn₅. Among these three solder joints, the shear strength of the SACBN/Cu joint is the highest, reaching 86.7 MPa. The shear strength of the SnBi/Cu solder joint is enhanced by the SACBN bump from 68.2 MPa to 75.2 MPa. Additionally, the addition of the SACBN bump shows a positive effect on suppressing the brittleness of the SnBi/Cu solder joint.

Owing to the superior mechanical performance, corrugated steel webs are extensively applied and their shear performance is critical, because of the thin wall. After the steel is corroded and the web is weakened, the problem of shear resistance may become more prominent. The shear performance of corrugated steel webs with local uniform loss was studied to simulate a common corrosion state. Twenty-eight FE models with different defect characteristics, containing defect height and web thickness, are established to simulate corroded corrugated webs. Shear capacity, shear strength, out-of-plane stiffness and bending stiffness are studied. Based on previous studies, the prediction formula is proposed to predict the residual shear strength. Additional FE models are built to validate the reliability. Results indicate that web thickness is the key factor to decide the deformation shape and shear capacity, compared with defect height. Bending stiffness decreases as defect increases. With 62.5% of the initial thickness, the influence of the variation of defect height on the bending stiffness is within 10%. Variation in thickness also affects the sensitivity of shear capacity to corrosion parameters and failure modes. When the thickness exceeds 1.25 mm, about 62.5% of the initial thickness, shear capacity is more sensitive to corrosion height than when the thickness is less than 1.25 mm. The proposed formula is validated and has a good agreement with the FE results, which could help to design the durability of corrugated steel webs and evaluate the performance of existing corrugated steel webs.

This paper presents the numerical investigation of nine Glass Fiber-Reinforced Polymer (GFRP) concrete deep beams through the use of numerically-efficient 20-noded hexahedral elements. Cracking is taken into account by means of the smeared crack approach and the bars are simulated as embedded rod elements. The developed numerical models are validated against published experimental results. The validation beams spanned a practical range of varying design parameters; namely, shear span-to-depth ratio, concrete specified compressive strength and flexural reinforcement ratio. The motivation for this research is to accurately yet efficiently capture the mechanical behavior of the GFRP-reinforced concrete deep beams. The presented numerical investigation demonstrated close correlations of the force–deformation relationships that are numerically predicted and their experimental counterparts. Moreover, the numerically predicted modes of failure are also found to be conformal to those observed experimentally. The proposed modeling approach that overcame previous computational limitations has further demonstrated its capability to accurately model larger and deeper beams in a computationally efficient manner. The validated modeling technique can then be efficiently used to perform extensive parametric investigations related to behavior of this type of structural members. The modeling method presented in this work paves the way for further parametric investigations of the mechanical behavior of GFRP-reinforced deep beams without shear reinforcement that will serve as the base for proposing new design guidelines. As a deeper understanding of the behavior and the effect of the design parameters is attained, more economical and safer designs will emerge.

A coupled experimental-numerical study on shear fracture in the concrete specimens with different geometries is carried out using compression tests. The crack initiation, propagation and final breakage of the specimens are experimentally studied under compression loading. The effects of specimen geometries on the shear fracturing path in the concrete specimens are also studied. The same specimens are numerically analyzed using an indirect boundary element method to predict the crack propagation paths of concrete specimens. These numerical results are compared with the existing experimental results proving the accuracy and validity of the proposed study.