极端环境下导管架平台连续倒塌鲁棒性评估

Robustness assessment of jacket platforms for progressive collapse under extreme environmental loading

基于Pushover和AP法分析平台结构极限状态及剩余强度储备比,探讨不同类别承载模式的构件对平台结构抗倒塌能力的影响规律;采用W_(DSR)、W_(RIF)和W_(SRF)确定性指标,评估平台结构鲁棒性和构件重要度。考虑平台抗力受环境载荷变化的影响,基于MSA和LSIA建立随机平台在随机载荷下的可靠度评估方法,提出导管架平台'安全评定图'概念,对服役平台全尺度载荷下的安全性进行标定,在此基础上,对导管架平台进行概率鲁棒性评估。研究表明:平台抗力对水平撑构件的失效不敏感,水平撑的确定性鲁棒性指标较大,可视为冗余性构件;斜撑对保证平台结构的鲁棒性起关键作用;这类构件的失效对结构承载能力影响相对显著,在进行平台结构鲁棒性设计时,应保证其具有足够的强度与韧性。提出的'安全评定图'能够提高平台概率鲁棒性评估的计算精度。

The ultimate limit state and residual strength reserve ratio of jacket platforms were analyzed based on alternate path ( AP) and Pushover methods, and the influence of component types on platforms' anti-collapse capacity was investigated. The certainty indexes of WDSR , WRIF and WSRF were used to assess the robustness of jacket platforms as well as the importance of components. Considering the impact of environmental loading on the ultimate bearing capacity of jacket platforms, random plat-form reliability assessment method under random loading was established based on multi strips analysis ( MSA) and load se-quence incremental analysis (LSIA). Combining MSA and LSIA, a novel safety assessment figure (SAF) was proposed to e-valuate the safety of jacket platforms under full scale environmental loading. Further, probabilistic robustness of the platform was assessed utilizing probabilistic redundancy index. The results show that the resistance of the platform is not sensitive to the failure of horizontal bracings, which can be regarded as the redundant components because their deterministic robustness index is more significant. Diagonal bracings play an important role in ensuring the robustness of platform structures. The failure of this kind of components will affect the capacity of the platform. Therefore, it should be ensured that the strength and toughness are sufficient in the design of jacket platforms. The SAF introduced in this paper can improve the calculation precision of proba-bilistic robustness evaluation.