Stay-in-place formwork (SIPF) systems represent a conventional formwork-free, corrosion-resistant substitute for construction of new reinforced concrete walls. The composite of infill concrete and thin-walled fibre cement board (FCB)/steel studs SIPF consists of a core concrete, filled between two FCBs that are connected to each other using steel studs, embedded to the concrete infill. Similarly, the concrete-filled Polyvinyl Chloride (PVC) hybrid system is comprised of extruded PVC interlocked encasements core-filled with concrete. These lightweight structural SIPFs are utilised in modular construction in which the system is prefabricated in the factory, transported to the site, erected and assembled for concrete casting. Further, the SIPF-encased wall is a composite system that facilitates taking advantage of mixed effects of reinforced concrete and SIPF. These are the major benefits of these systems compared to conventional formwork systems. However, there is a gap in knowledge regarding the strength and ductility measurement of SIPF-encased walls under eccentric axial loads that is presented in this paper. A series of tests was conducted to failure on both composite walls and compared with the reference specimens, i.e. standard walls (STWs). Substantial finite element (FE) studies considering material and geometric nonlinearities as well as contact behaviour are also performed. After a reasonable model verification against test results, a comprehensive parametric investigation accounting for the concrete compressive strength, the thickness of SIPF components (i.e. steel studs, FCB, and PVC), longitudinal bar reinforcement, and axial load ratio is performed. Further, the experimental and numerical results are used to assess the suitability of the theoretical formulation specified in the current Australian Standard (AS3600) for the axial-flexural interaction resistance of SIPF-encased walls. It is demonstrated that the predictions from the current design specifications are overall conservative. Further, it is found that FCB/steel studs SIPF effectively contributes to improve curvature ductility index and axial-flexural strength compared to STWs.

固定模板（SIPF）系统是传统的无模板，耐腐蚀的替代品，可用于建造新的钢筋混凝土墙。填充混凝土和薄壁纤维水泥板（FCB）/钢钉的组合SIPF由填充在两个FCB之间的芯混凝土组成，两个FCB之间通过钢钉相互连接，并嵌入混凝土填充物中。同样，混凝土填充的聚氯乙烯（PVC）混合系统由挤塑的PVC互锁外壳组成，这些外壳用混凝土芯填充。这些轻型结构SIPF用于模块化结构，该系统在工厂预制，运输到现场，安装和组装以进行混凝土浇筑。进一步，装有SIPF的墙是一种复合系统，有助于利用钢筋混凝土和SIPF的混合效果。与传统模板系统相比，这些是这些系统的主要优点。但是，本文介绍的关于SIPF包裹的墙在偏心轴向载荷下的强度和延性测量的知识尚有不足。对两个复合墙均进行了一系列破坏测试，并与参考样本（即标准墙（STW））进行了比较。还进行了考虑材料和几何非线性以及接触行为的实质性有限元（FE）研究。在根据测试结果进行合理的模型验证之后，对混凝土的抗压强度，SIPF组件的厚度（即 钢钉，FCB和PVC），纵向钢筋和轴向载荷比。此外，实验和数值结果用于评估现行澳大利亚标准（AS3600）中指定的理论公式对SIPF包裹墙的轴向-弯曲相互作用阻力的适用性。结果表明，当前设计规范的预测总体上是保守的。另外，发现与STW相比，FCB /钢制螺栓SIPF有效地有助于改善曲率延展性指数和轴向抗弯强度。实验和数值结果用于评估现行澳大利亚标准（AS3600）中指定的理论公式对SIPF封装墙体的轴向-弯曲相互作用阻力的适用性。结果表明，当前设计规范的预测总体上是保守的。另外，发现与STW相比，FCB /钢制螺栓SIPF有效地有助于改善曲率延展性指标和轴向抗弯强度。实验和数值结果用于评估现行澳大利亚标准（AS3600）中指定的理论公式对SIPF封装墙体的轴向-弯曲相互作用阻力的适用性。结果表明，当前设计规范的预测总体上是保守的。另外，发现与STW相比，FCB /钢制螺栓SIPF有效地有助于改善曲率延展性指数和轴向抗弯强度。