Design method for precise-forming of air-supported structures considering weld seams

摘要

Air-supported structures have been increasingly used as formwork for constructing thin concrete shell structures. However, shape deviation from design shape of air-supported structures as airform can result in varying radius of curvature and differing stress distribution. Precise-forming is an inevitable requirement for the design of air-supported structures. This paper presents a design method of air-supported structures considering weld seams for precise-forming. Simulation method of weld seams is integrated in the full design process. Cable elements are included into computation and fill moduli of membrane elements are modified for simulating the influence of seams in warp and fill directions respectively. Force-finding for real stress distribution is utilized to deal with the influence of seams on stress distribution. Residual Pressure Method for cutting forms is adopted to avoid solving zero stress state, in which displacement restriction is imposed on the boundary in deflation analysis for actual construction. Based on a Datun air-supported structure in the shape of hemisphere and cylinder, which is designed to be 71.3 m in diameter and 39.15 m tall, three models with different considerations of weld seams are compared to reveal the influence of seams on stress distribution and cutting form. Measurement results of actual structure demonstrate excellent forming precision of the proposed design method for precise-forming.