装配式混凝土预制楼梯拆模起吊安全性监测数据
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装配式混凝土预制楼梯是房屋建筑行业中非常重要的装配式构件。在建筑施工中，传统的楼梯通常是在施工现场支模、绑扎钢筋、浇筑混凝土来完成。而预制楼梯则是在专门的生产场地，按照设计要求和标准规范，通过工业化的方式提前制作完成。预制楼梯具有质量更易控制、施工速度快、减少现场湿作业、降低环境污染等优点。为了确保构件的起吊施工安全，减免构件实体破坏、开裂和报废造成经济损失，预制楼梯拆模起吊安全性的数据监测是构件生产运输必不可少的工作。该监测数据能够评估预制楼梯拆模起吊施工安全性，帮助生产施工方判断该构件是否满足安全拆模起吊要求，能否按时拆模起吊运输，对建筑行业的施工进度、人员安全等具有重要意义，并具有可以在行业内进行广泛运用的前景。制作边长为100mm的立方体混凝土试件，在现场同条件养护24h用标准试验方法检测得立方体抗压强度。按照如下公式计算：fcc=F/A，公式中fcc为混凝土立方体试件抗压强度，单位为MPa，计算结果应精确至0.1MPa；F为试件破坏载荷，单位为N；A为试件承压面积，单位为mm2。混凝土强度等级小于C60时，用边长为100mm的立方体非标准试件测得的强度值均应乘以尺寸换算系数0.95。再分别计算出三个试件的抗压强度值，取平均值作为该组试件抗压强度代表值 fcuo，与设计强度标准值进行相除，得到最后的达到设计强度百分比。综上所述，达到设计强度百分比的计算为P=(F1/A*0.95+F2/A*0.95+F3/A*0.95)/3/fcuo，结果精确至1%。安全拆模起吊时，同条件养护混凝土试件抗压强度不应小于设计强度的50%；若未满足要求，不得拆模起吊，必须延迟起吊时间。如本次提取的监测数据的计算分析结果显示，该批构件满足安全拆模起吊要求，可以按时拆模起吊。
Prefabricated concrete precast stairs are critical prefabricated components in the building construction industry. In traditional construction, stairs are typically completed on-site through formwork erection, steel bar binding and concrete pouring. In contrast, prefabricated stairs are prefabricated in advance via industrialized methods in specialized production sites in accordance with design requirements and standard specifications. Prefabricated stairs boast advantages including easier quality control, faster construction speed, reduced on-site wet work, and lower environmental pollution. To ensure lifting construction safety and avoid economic losses caused by physical damage, cracking and scrapping of components, safety monitoring during demolding and lifting of precast stairs is an essential task in component production and transportation. This monitoring data can evaluate the safety of demolding and lifting construction for precast stairs, help production and construction parties judge whether the components meet the safety requirements for demolding and lifting, and whether they can be demolded, lifted and transported on time, which is of great significance to construction progress and personnel safety in the construction industry, and has broad application prospects in the industry. Concrete cube specimens with a side length of 100 mm were prepared, and their cube compressive strength was tested using standard test methods after 24 hours of on-site curing under the same conditions. The compressive strength is calculated by the formula: $f_{cc} = F/A$, where $f_{cc}$ is the compressive strength of the concrete cube specimen, with the unit of MPa, and the calculation result shall be accurate to 0.1 MPa; $F$ is the failure load of the specimen, with the unit of N; $A$ is the bearing area of the specimen, with the unit of mm². When the concrete strength grade is lower than C60, the strength values measured with non-standard 100 mm side length cube specimens shall be multiplied by the size conversion factor of 0.95. Calculate the compressive strength values of the three specimens respectively, and take the average value as the representative compressive strength value $f_{cuo}$ of this group of specimens. Divide this value by the standard design strength value to obtain the final percentage of reaching the design strength. In summary, the calculation formula for the percentage of reaching design strength is $P = (F_1/A*0.95 + F_2/A*0.95 + F_3/A*0.95)/(3*f_{cuo})$, with the result accurate to 1%. For safe demolding and lifting, the compressive strength of concrete specimens cured under the same conditions shall not be less than 50% of the design strength; if the requirement is not met, demolding and lifting are not allowed, and the lifting time must be delayed. As shown by the calculation and analysis results of the monitoring data extracted this time, this batch of components meets the safety requirements for demolding and lifting, and can be demolded, lifted and transported on time.
