This paper aims to study the effects of different parameters of precast concrete double-tee (DT) girder bridges on the live-load distribution factors (LLDFs) using 3D computational models. The models were created for two DT girder bridges (including 584 mm deep and 762 mm deep bridges) tested with a rating truck using solid and shell elements in CSi Bridge. From the field tests, LLDFs were initially calculated. The models were calibrated with the field LLDFs and then different parameters, encompassing span length, concrete strength, deck width, diaphragm usage, and width to length ratio, were adjusted individually to explore the variation in LLDFs. Each of the parameters was investigated in this study for DT girder bridges. The AASHTO LRFD interior LLDFs were generally accurate for the DT girder bridges with significant joint damage. It was demonstrated that the deck width, concrete strength, and diaphragm location had very little influence on the LLDFs, whereas the span length and width to length ratio had significantly affected the LLDFs. Strictly speaking, the exterior and interior LLDFs decreased as the span length increased. The pattern for the interior LLDFs is only in agreement with the AASHTO LRFD specifications, while the pattern for the exterior LLDFs is not consistent with the AASHTO LRFD LLDFs calculated using the lever rule without consideration of span length. As a final point, as the width to length ratio increased, the LLDFs increased.

本文旨在使用3D计算模型研究预制混凝土双三通（DT）梁桥的不同参数对活荷载分布因子（LLDF）的影响。该模型是针对两个DT梁桥（包括584 mm深和762 mm深的桥）创建的，这些桥使用CSi Bridge中的实心和壳单元用额定载荷卡车进行了测试。根据现场测试，最初计算了LLDF。使用现场LLDF对模型进行校准，然后分别调整跨度长度，混凝土强度，桥面宽度，隔板使用情况以及宽长比等不同参数，以探索LLDF的变化。在这项研究中研究了DT梁桥的每个参数。AASHTO LRFD内部LLDF通常对于DT大梁桥具有明显的接头损坏是准确的。结果表明，甲板宽度，混凝土强度和隔板位置对LLDF的影响很小，而跨度长度和宽度与长度之比对LLDF的影响很大。严格说来，外部和内部LLDF随着跨度的增加而减小。内部LLDF的图案仅与AASHTO LRFD规范一致，而外部LLDF的图案与使用杠杆规则计算而未考虑跨度长度的AASHTO LRFD LLDF不一致。最后，随着长宽比的增加，LLDF也增加了。随着跨度长度的增加，外部和内部LLDF减少。内部LLDF的图案仅与AASHTO LRFD规范一致，而外部LLDF的图案与使用杠杆规则计算而未考虑跨度长度的AASHTO LRFD LLDF不一致。最后，随着长宽比的增加，LLDF也增加了。随着跨度长度的增加，外部和内部LLDF减少。内部LLDF的图案仅与AASHTO LRFD规范一致，而外部LLDF的图案与使用杠杆规则计算而未考虑跨度长度的AASHTO LRFD LLDF不一致。最后，随着长宽比的增加，LLDF也增加了。