The high-strength bolt shear connector in prefabricated concrete slab has advantages in applications as it reduces time during the construction of steel-concrete composite building structures and bridges. In this research, an innovative and advanced bolt shear connector in steel-concrete composite structures is proposed. To investigate the fundamental mechanical behavior and the damage form, 22 static push-off tests were conducted with consideration of different bolt dimensions, the reserved hole constraint condition, and the dimension of slab holes. A finite element (FE) model was established and verified by using test results, and then the model was utilized to investigate the influence of concrete strength, bolt dimension, yield strength, bolt pretension, as well as length-to-diameter ratio of high strength bolts on the performances of shear connectors. On the basis of FE simulation and test results, new design formulas for the calculation of shear resistance behavior were proposed, and comparisons were made with current standards, including AISC, EN 1994-1-1, GB 50017-2017, and relevant references, to check the calculation efficiency. It is confirmed that the proposed equation is in better agreement with the experimental results.

The rectangular concrete-filled steel tube (RCFST) has been widely applied into many engineering fields like buildings and bridges. However, the shear mechanisms and the universal design methods under lateral shear forces still remain to be fully understood. In this paper, the composite action of RCFST columns under lateral shear forces was systematically investigated with improved 3-dimensional finite element simulations. The models adopted the improved material constitutive models and detailed contact interactions between the encased steel tube and core concrete. On the basis of available test data and numerical results of parametric studies, the critical shear span ratio and its variation range were determined. The composite effect and interactions between the encased steel tube and core concrete under different configurational dimensions and loading conditions were investigated. Calculation formulas of the shear stiffness and capacity were proposed based on identified features. The cooperative working mechanism and the constraining effect of steel tube were considered. The proposed calculations were then compared to available design regulations in different countries, and yielded more accurate predictions than the others.

Petroleum coke and lignite are two important fossil fuels that have not been widely used in China. Petroleum coke-lignite slurry (PCLS), a mixture of petroleum coke, lignite, water, and additives, efficiently utilizes the two materials. In this study, we investigate the effects of the proportion (a) of petroleum coke on slurryability, rheological behavior, stability, and increasing temperature characteristics of PCLSs. The results show that the fixedviscosity solid concentration (x 0 ) increases with increasing a. The x 0 of lignite-water slurry (LWS, a = 0) is 46.7 %, compared to 71.3 % for the petroleum coke-water slurry (PCWS, a = 100 %), while that of PCLS is in between the two values. The rheological behavior of PCLS perfectly fits the power-law model. The PCWS acts as a dilatant fluid. As a decreases, the slurry behaves first as an approximate Newtonian fluid, and then turns into a pseudo-plastic fluid that exhibits shear-thinning behavior. With increasing a, the rigid sedimentation and water separation ratio (WSR) increase, indicating a decrease in the stability of PCLS. When a is 60-70 %, the result is a high-quality slurry fuel for industrial applications, which has high slurryability (x 0 = 57-60 %), good stability (WSR \ 2 %), and superior pseudo-plastic behavior (n & 0.9).