Although a well established comprehension of the torsional design is a must for an accurate and economic design of concrete members, however, after 180 years of research very little is known about the torsion design of lightweight concrete (LWC) beams. Several projects are undergoing with the objective of improving design provisions, including but not limited to those for shear, torsion, and LWC, however, very limited studies have tackled either torsion design or combined torsion, shear and flexure design of LWC beams. This current study examines the current design of LWC beams under torsion. Selected torsion design provisions were reviewed and outlined. Findings from previous experimental testing of LWC beams under torsion were reviewed and outlined. An experimental database was compiled from previous works available in the literature, with a total of 90 beams tested under significant torsion. The cracking and ultimate torsion strength of all tested beams were calculated using selected design codes. The calculated cracking and ultimate torsion strength were compared to the experimentally observed ones. The effect of various parameters on the safety, accuracy, and consistency of the torsion design of LWC beams using various design codes was investigated. Cracking torque needed a revisit in order to account for LWC and using fibers in the concrete mix. A new formula for cracking torsional moments, which included the effect of all effective parameters was developed, validated, and proposed. The proposed formula was found to be remarkably better than existing design codes. More experimental testing for LWC beams under combined loading is needed in order to refine existing design codes and proposed formula.

尽管对于混凝土构件的精确和经济设计来说，必须对扭转设计有充分的了解，但是，经过180年的研究，对轻质混凝土（LWC）梁的扭转设计知之甚少。为了改善设计规定，正在进行多个项目，包括但不限于剪切，扭转和轻质混凝土的设计规定，然而，非常有限的研究涉及扭转设计或轻质混凝土梁的扭转，剪切和挠曲组合设计。这项当前的研究检查了扭转下轻质混凝土梁的当前设计。审查并概述了选定的扭转设计规定。回顾并概述了以前在扭力作用下的轻质混凝土梁的实验测试结果。实验性数据库是根据文献中的先前工作汇编而成的，在严重扭转下总共测试了90个光束。使用选定的设计规范计算了所有测试梁的抗裂强度和极限抗扭强度。将计算出的龟裂和极限抗扭强度与实验观察到的进行比较。研究了各种参数对使用各种设计规范的LWC梁的扭转设计的安全性，准确性和一致性的影响。需要重新考虑开裂扭矩，以解决轻质混凝土和在混凝土混合物中使用纤维的问题。提出，验证和提出了一种新的裂纹矩公式，其中包括所有有效参数的影响。发现拟议的公式明显优于现有的设计规范。