Abstract

When a penstock serves a water supply purpose for multiple hydrogenerators in a hydroelectric power plant (HPP), a bifurcation structure should be installed between the main pipe and the branch pipes. This study focuses on a rib-strengthened steel bifurcation structure (RSSBS) with an emphasis on its hydraulic load-bearing mechanism. The finite element method is used with the contact and material non-linearities considered. The numerical simulation results agree reasonably well with in-situ measured data. Our research has underlined the critical role of the crescent-shaped rib (CSR) in lessening the stress-concentration at the bifurcation. The CSR is found to separate from the surrounding concrete under the internal water pressure (IWP), thus causing less IWP to be transmitted to the concrete. Despite the fact that the CSR is not in tension-stress-only status, however, the tensile-stress level is well within an acceptable range. In this context, the CSR should not necessarily be in tension-stress-only status, which is recognized as an ideal stress state in the conventional design philosophy. The findings also suggest that the importance of the concrete should not be stressed too much in the structural design of RSSBSs considering its backfilling role.

• Highlights

• The role of the crescent-shaped rib in strengthening local stiffness is underlined.

• The rib is found to separate from the concrete under the internal water pressure.

• The simulation results agree reasonably well with in-situ measured data.

摘要

当压力钢管为水力发电厂多台水轮发电机组供水时，主管与支管之间应设置分叉结构。本研究重点关注肋骨强化钢分叉结构（RSSBS），重点研究其液压承载机制。使用有限元方法并考虑接触和材料非线性。数值模拟结果与现场测量数据相当吻合。我们的研究强调了新月形肋 (CSR) 在减轻分叉处应力集中方面的关键作用。发现 CSR 在内部水压 (IWP) 的作用下与周围的混凝土分离，从而导致较少的 IWP 传输到混凝土。然而，尽管 CSR 并非仅处于拉应力状态，但拉应力水平完全在可接受的范围内。在这种背景下，CSR不一定处于仅拉应力状态，这在传统设计理念中被认为是理想的应力状态。研究结果还表明，考虑到混凝土的回填作用，在 RSSBS 的结构设计中不应过分强调混凝土的重要性。

• 强调

• 强调了新月形肋在增强局部刚度方面的作用。

• 发现肋骨在内部水压作用下与混凝土分离。

• 模拟结果与现场测量数据相当吻合。