막 구조는 자유로운 형태, 경량성, 내구성, 햇빛 투광성 및 균질성 때문에 전 세계적으로 현대 건축물에 다양하게 사용되어 왔다. 새로운 막 재료의 개발로 새로운 건축 구조설계에 대한 가능성을 열어가고 있다. 최근 주로 사용되는 막 구조의 지붕 재료에는 PVC, PVF, PVDF, PTFE 코팅 막재 및 ETFE 막재가 수로 사용되고 있다. 건축용 막은 내화성, 강도 부족, 인열강도, 내구성 및 탄성 등에 대한 몇가지 문제점들을 가지고 있다. 이러한 문제점들을 평가하기 위해서 본 연구에서는 PVDF 코팅 폴리에스터 막재에 대한 인장강도, 인열 강도 및 반복하중거동 시험을 실시하여 건축용 막재의 기초적인 역학적 특성을 분석하고자 한다. 막재의 탄성계수는 337.30~1257.63N/㎟, 신율은 17.90~26.91%로 주어졌다.

In this study, the 'force density method' for shape finding of cable net structures is presented. This concept is based on the force-length ratios or force densities which are defined for each branch of the net structures. This method renders a simple linear 'analytical form finding' possible. If the free choice of the force densities is restricted by further condition, the linear method is extended to a nonlinear one. The nonlinear one can be applied to the detailed computation of networks. In this paper, the general inverse matrix is introduced to solve the nonlinear equilibrium equation including Jacobian matrix which is rectangular matrix. Several examples for linear and nonlinear analysis applied additional constraints are presented. It is shown that the force density method is suitable for form finding of cable net and the general inverse matrix can be applied to solve the nonlinear equation without Lagrangian factors.

In general, the cutting pattern of the membrane structures is determined by dividing the complicated curved 3-D surface into several 2-D plane strip by using flattening technique. In this procedure, however, some discrepancies ore occurred between actual stresses of equilibrated state and designed uniform stresses because the material properties are not considered. These deviations can cause the critical structural problems, wrinkling or overstress, and thus a optimization process should be considered. In this paper, a new analytical method for determining an optimum cutting pattern considering material properties is presented. Here, iterative procedure is introduced to decrease the errors caused in numerical process. The optimization method proposed can diminish the deviations occurred by material properties and numerical errors, simultaneously. As a results, it is shown that the final stress distributions for the HP shell model are sufficiently near to design stress distributions, and it can be concluded that this method can be used to obtain the optimized cutting pattern of membrane structures.