高大模板支撑体系的防错机理和对策研究

The collapse of high formwork support system happens frequently. The major cause of the collapse has been attributed to model errors which occur very frequently. Attempts to correct and accept these errors have been unsuccessful in the past. In this research we propose a new, error-proof ideal in the design of formwork support system. The objective is to produce a design method that will eliminate error, limit error, let error easily be corrected and prevent collapse all together. (1) We will investigat workers' actions, talk with workers and conduct on-site surveys to identify why human errors came to be and model human errors; (2) We will use a risk-assessment method to quantify the significance of each error in consideration of the error occurrence rate, the correction efficiency and the loss of structural reliability caused by human errors. We will give defence grades for different kinds of errors and propose defence mechanisms for each kind of errors according to their defence grades; (3) We will develop an error-proof structural system that will call for an exact placement of the structural elements and connections，and exact design of error-proof joints and accessory equipments. We will verify error-proof joint using experimental methods, and will quantify the effect on error-prevention of the new structural system in terms of both user experience and interview; (4) We will perform full-scale experiments to investigate the ultimate capacity of the new structural system and mechanical properties of joints, and will use the data to validate nonlinear finite element models of the system. We will proposing probability design methods and finishing standardized design. The final outcome of this research can provide both new method to prevent collapse of high falsework fundamentally and new idea to prevent other construction accidents.

高大模板支撑体系坍塌事故频发，大概率结构性人为错误是主要原因。在“改错”不奏效和“容错”不合理的情况下，本项目基于“防错”、“限错”、“容易改错”和“防连续性坍塌”的防错设计思想，在前期研究的基础上，进行以下研究：(1)通过施工人员的行为观察、访谈和调研, 在工人-支撑体系关系层面上，研究结构性人为错误的发生机理和规律；(2)考虑错误的发生概率、改错效果和对可靠度的影响，提出错误危险性的综合量化计算方法和评价指标，制定防错设防水准，研究各类错误的防错机理；(3)研究防错型模板支撑体系的结构型式、连接方式、构造措施和辅助设施，进行节点设计和检测，通过施工人员的体验和访谈，验证防错效果；(4)在节点力学性能试验和防错型结构体系足尺试验的基础上，进行承载力的计算分析，提出承载能力极限状态设计法和防塌验算法，进行标准化设计。为防止高大模板支撑体系坍塌事故提供新方法，为防止其他施工事故提供新思路。

..高大模板支撑体系坍塌事故不断发生，各类施工管理方法收效不大，本项目借鉴公路工程中已取得明显效果的“设计防错”的思想，研究高大模板支撑体系的防错机理和对策。课题组成员在项目申请期间和项目执行期间，经过现场调查、人员访谈、现场试验、室内试验和理论研究，按期完成研究计划。在设计防错方面进行了较为系统的研究，掌握了敏感性较大的人为错误的统计规律，了解了结构性人为错误的发生机理；提出了一种防连续倒塌高大模板支撑体系以及两个阶段防连续倒塌设计法，提出了模板支架容错设计的概率优化设计方法、无人为错误和有人为错误高大模板支架的概率极限承载力设计法；将价格仅高出普通钢材30%而强度高达500MPa的索氏体不锈钢应用到高大模板支撑体系中，以期减少施工人员的劳动强度，完成了材料拉伸试验、压缩试验和单根钢管的受压承载力试验；对施工人员的工作行为进行现场调查、人员访谈、统计分析和计算机模拟，掌握了施工人员工作行为的特征，给出了统计模型，为进一步研究施工人员—模板支架的相互作用打下了基础。在防错节点方面，在承插型自锁式节点的基础上，提出采用用铸造方式加工C型卡和U型卡，避免施焊操作和过于施工工人责任心的依赖，保证节点质量。在施工荷载方面，给出了作用在模板支架上主要水平动力荷载的周期特征和取值建议，给出型钢混凝土梁浇筑过程中高大模板支架承担荷载的比例，经过对20余个施工现场的调研，给出了混凝土浇筑前后材料荷载的统计特征以及作用在无梁楼盖上活荷载的统计特征。研究成果可提高模板支架的安全性和抗人为错误的韧性，事故发生时给施工人员提供逃生机会，填补我国此类结构设计的空白，并为制定合理安全技术规范打下基础。部分研究成果已写入《建筑施工模板和脚手架试验标准》（JGJT 414-2018）。