Delayed Collapse of Wooden Folding Stairs

World Multidisciplinary Civil Engineering-Architecture-Urban Planning Symposium - WMCAUS

土木建筑工程

Krentowski, Janusz^1 ; Chyzy, Tadeusz^1

Bialystok University of Technology, Wiejska str. 45E, Bialystok

15-351, Poland^1

关键词: Complex loads;    Computational model;    Faulty connection;    Laboratory strength;    Load transmission;    Serious injuries;    THREE-DIMENSIONAL FEM;    Weakest links;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/245/3/032055/pdf
DOI  :  10.1088/1757-899X/245/3/032055

学科分类：土木及结构工程学

来源: IOP

【 摘 要 】

During operation of folding stairs, a fastener joining the ladder hanger with the frame was torn off. A person using the stairs sustained serious injury. In several dozen other locations similar accidents were observed. As a result of inspections, some threaded parts of the screws were found in the gaps between the wooden elements of the stairs' flaps. In the construction a hatch made of wooden strips is attached to an external frame by means of metal hangers. Laboratory strength tests were conducted on three samples made of wooden elements identical to the ones used in the damaged stairs. Due to complex load distribution mechanism acting on the base of the structure, a three-dimensional FEM model was created. An original software was used for calculations. Five computational model variants were considered. As a result of the numerical analyses, it was unquestionably shown that faulty connections were the cause of the destruction of the stairs. The weakest link in the load transmission chain were found to have been the screws connecting the hatch board with the hangers.