Finite Element Analysis of the Mechanical Properties of Shear Wall-Composite Slab Joints Anchored by Slab-End Projecting Reinforcement in Nuclear Power Plants

Nuclear Power Plants （NPPs） are typically characterized by concrete structures with thick walls and thick slabs. Their shear wall-slab joints are generally regarded as fixed supports， which are the key components affecting the mechanical properties and failure modes of the overall structure. Cast-in-situ concrete slabs are currently the predominant floor systems adopted in such structures； however， they suffer from drawbacks including great demand for formwork and propping， prolonged construction periods， and high energy consumption. Applying the formwork-free and minimal-propping concrete composite slab technology to wall-slab joints can effectively overcome these limitations. This study proposed a concrete shear wall-concrete composite slab joint with slab-end hooked projecting reinforcement anchorage for nuclear power plant structures. Based on an ABAQUS three-dimensional solid finite element model validated against seismic test results of the joint， the effects of concrete strength （C40， C50， and C60） and slab reinforcement ratio （0.45%， 0.58%， and 0.71%） on the seismic performance of the joint were systematically analyzed. The results indicated that all models failed in a flexural mode at the slab ends. Concrete strength had a negligible effect on joint bearing capacity， with differences of less than 2%. However， increasing concrete strength led to higher initial stiffness and reduced ductility. Compared with joints using C40 concrete， those with C50 and C60 concrete exhibited increases in forward （reverse） initial stiffness of 10.92% （6.89%） and 20.30% （11.87%）， respectively， while the forward （reverse） ductility coefficients decreased by 6.28% （2.45%） and 17.93% （14.08%）， respectively. Increasing the slab reinforcement ratio enhanced the bearing capacity and initial stiffness but reduced ductility. Compared with joints having a reinforcement ratio of 0.45%， those with ratios of 0.58% and 0.71% showed increases in forward （reverse） bearing capacity of 15.97% （23.58%） and 30.79% （34.69%）， respectively； increases in initial stiffness of 17.22% （7.48%） and 31.55% （19.34%）， respectively； and decreases in ductility coefficients of 16.45% （20.37%） and 19.59% （29.79%）， respectively. For all parameter cases， the bearing capacity of the precast joint differed from the theoretical value of the cast-in-situ joint by less than 10%， and all ductility coefficients exceeded 5. These results indicate that shear wall-concrete composite slab joints anchored by slab-end projecting reinforcement can achieve reliable fixed connections and exhibit satisfactory seismic performance.