This paper presents the findings of an investigation on early-age thermal behavior of concrete segmental box girders using finite element (FE) analysis. A FE segmental box-girder diaphragm model was created to evaluate the effect of its flanges, webs, volume-to-surface area ratio (V/A), and heat of cement hydration on the temperature development of the segment at an early age. Isothermal calorimetry testing was conducted on the cementitious materials of four normal and a high-strength concrete mix designs to obtain the heat of hydration and temperature rise, which then were used in the preprocessing of the FE schemes. Based on the investigation on 3 different model shapes consisting of the full-, no-flange-, and core-segment models, the no-flange-segment model was selected as the simplified and representative model for segmental box-girder diaphragms in thermal analysis. Additionally, a parametric study on various V/A of the no-flange- segment model indicates that the segmental box-girder diaphragms are considered mass concrete when using high-strength concrete regardless of the V/A, and measures should be implemented to prevent unexpected thermal cracking.

本文介绍了使用有限元 (FE) 分析对混凝土管段箱梁早期热性能进行的调查结果。创建了有限元节段箱梁隔膜模型，以评估其翼缘、腹板、体积表面积比 (V/A) 和水泥水化热对早期节段温度发展的影响。对四种普通和高强度混凝土配合比设计的胶凝材料进行等温量热测试，以获得水化热和温升，然后用于有限元方案的预处理。基于对由全段、无法兰和核心段模型组成的 3 种不同模型形状的调查，在热分析中，无法兰段模型被选为节段箱梁隔板的简化和代表性模型。此外，对无法兰段模型各种 V/A 的参数研究表明，在使用高强混凝土时，无论 V/A 大小如何，均将节段箱梁隔板视为大体积混凝土，应采取措施防止意外的热裂。