underwater_const_syts

Underwater construction 2024

Authors: Kinga Korniejenko, Szymon G ˛adek, Piotr Dynowski, Doan Hung Tran, Magdalena Rudziewicz, Sebastian Pose, and Thomas Grab Additive manufacturing, or 3D printing, as it is more commonly known, is emerging as a game-changer in various fields, including automated construction in challenging environments such as underwater. However, it is not perfect, despite having been tested in these environments. This study explores the advancements of 3D printing for underwater applications and identifies areas for refinement and enhancement, including technology and materials.

Authors: Fantong Lin, Xianxiang Zhou, Jian Zhao, Lan Xiao, Lubo Tang, Ziye Liu, and Jianshuai Wang The authors used 3D models to study how underwater explosions affect shell structures at the bottom of the ocean. They looked at different shapes of these structures, like half-spheres and half-cylinders made of reinforced concrete. Using special software, they tested various factors like the type of explosion, distance, and water pressure. They found that these structures are damaged more when hit by shock waves in water than in air.

Authors: untao Sun, Jingzhu Huang, Zhiwei He, Jiahe Wang, Dawei Zhan, Qingxiong Zhu The study addresses the issue of blasting vibration generated during underwater engineering, which can cause significant damage to the surrounding environment. It shows that predicting the blasting peak particle velocity (PPV), which represents the maximum velocity of ground vibration caused by the detonation of explosives during blasting, can be utilized to mitigate these adverse effects.

Authors: Mohamed ElMenshawy, Lingzi Wu, Brian Gue, and Simaan AbouRizk This research project aimed to automate the pipe spool fabrication scheduling process for industrial projects. It explains the challenges involved in the current manual scheduling process and proposes the development of a reinforcement learning model to handle these tasks more efficiently. The ultimate goal is to minimize manual intervention and improve fabrication shops' scheduling processes.

01 - Experimental Investigation of the Evolution Process of Suspended Pipelines through River Bottoms under Unsteady Flow Conditions

Authors: Changjing Fu, Yangming Xu, and Tianlong Zhao This document explains the risks and mechanisms associated with water-induced disasters affecting long- distance oil and gas pipelines, particularly those crossing river channels. It discusses the findings from a flume model test that investigates the impact of unsteady flow conditions on riverbed evolution and pipeline suspension during floods.

Authors: Sung Youn Boo, Yoon-Jin Ha, Steffen Allan Shelley, Ji- Yong Park, Chang-Hyuck Lim, and Kyong-Hwan Kim This document describes a study focused on developing and validating a new Tension Leg Platform (TLP) floating wind platform with a 15 MW turbine for offshore wind farms in Korea. The study aims to ensure the platform's feasibility and resilience under extreme typhoon conditions and to minimize pre-service costs and risks by designing a wet-towable platform. The study also outlines the design process, analysis, and validation against industry standards to confirm compliance with design requirements for the planned site.

Authors: Xiaohe Pan, Mengzhuo Liu, Jifeng Zhu, Lipeng Huo, Zheng Peng, Jun Liu, and Jun-Hong Cui This document discusses the development and evaluation of a new protocol, the Robust and Adaptive Pipeline Medium Access Control (RAP-MAC), for underwater acoustic networks. It highlights the protocol's features, such as its adaptability, efficiency, and robustness, and shares the results of simulations and sea trials that demonstrate its effectiveness in enhancing communication in underwater environments.

Authors: Xiaotong Han, Liang Zhu, Xiaoxia Jiang, Wei Han Khor, Hooi Siang Kang This paper explains a new welding method, the flux band-constrained arc ultra-narrow gap welding (UNGW), for improving the quality of welded joints in underwater cast steel pipelines. It highlights the advantages of UNGW over traditional welding methods, describes the experimental study conducted to optimize welding parameters, and analyzes the microstructural and mechanical properties of the welds. It also suggests potential welding process improvements by manipulating the flux band composition.

42 - Exploring the effects of ambient conditions on the cryogenic cooling times of offshore structures: Towards optimising sustainability and the decommissioning timescale

Authors: Kenneth Bisgaard Christensen, Alireza Maheri, and M. Amir Saddiq This study investigates the effects of ambient conditions on cryogenic cooling times for medium-carbon steel pipes, focusing on factors such as air velocity, ambient temperature, and cooling medium for simulations. It aims to validate the viability of cryogenic conditions for low- energy fracturing in carbon steel and explores the efficiency of a proposed cryogenic cooling and cutting system. The research also highlights the importance of insulating effects and discusses the trade-offs between cooling efficiency, costs, and energy consumption.

Authors: Hongqi Ma, Haibin Xiao This document provides an overview of the development and implementation of intelligent construction and smart operation technologies in the Lancang River Hydropower Project. It summarizes the research, development, and practical applications of these technologies, particularly in the context of high earth–rock and roller compacted concrete dams, and introduces specific technologies and functions related to dam safety, engineering control, disaster prevention, and environmental monitoring.

This internet link allows every person interested to access and download the UK HSE research reports. It must be emphasized that the UK HSE has been one of the 1st official bodies to emit guidelines and laws to improve the working conditions offshore and that its impact remains essential.

07 - Development and Application of Offshore Trade Authenticity Verification Platform Based on Blockchain

Authors: Hai-Feng Chen, Lv Zhang, Shuai Wang , Shan- Shan Shi Offshore trade is common in international trade, but its hidden capital flow poses risks. Authenticity verification is crucial for economic security. This paper presents a blockchain-based verification platform that meets user needs and shows good performance. It promotes regional trade, supports financial institutions, and empowers offshore trade development.

08 - A novel design of multifunctional offshore floating platform structure based on topology optimization.

Author: Nouman Saeed, Jingliang Gong, Yuejia Wan, Kai Long, Ayesha Saeed, Liu Mei, Chen Xiong, Wujian Long, Haijun Zhou, Lixiao Li Floating platforms are an affordable choice for gathering energy in deep seawater. Key design concerns are lightweight and structural stability, ensuring they can bear loads. This paper presents a new lightweight offshore platform design that uses density-based topology optimization for wind-solar-wave energy. The design addressed extreme sea conditions and passed strength checks under DNV code standards, achieving a total mass reduction of 40. 82% and improved stiffness and durability.

10 - A Corrosion and Repair-Based Reliability Framework for Offshore Platforms.

Authors: Mehdi Hajinezhadian, and Behrouz Behnam Offshore platforms are critical structures that often experience severe corrosion, which can weaken them over time. Although many anti-corrosion methods exist, a comprehensive management plan is necessary for their long-term operation. This work suggests a corrosion and repair reliability framework for these platforms. It shows that corrosion depth significantly impacts repair effectiveness. The study proposes a corrosion growth model based on various standards to aid platform owners in safety decisions.

11 - Effect of Doping Trace Rare Earth Elements on Corrosion Behavior of EH36 Offshore Platform Steel

Authors: Shujia Zheng, Na Liu, Yang Liu, Xiaoning Wang, Lina Qiu, and Aijun Gong EH36 offshore platform steel, La (0. 0031%), Ce (0. 0027%), and Pr (0. 0001%) steel were studied for corrosion. Immersion experiments showed that rare earth elements reduce corrosion rates. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyzed corrosion products. Electrochemical tests showed rare earths increased charge transfer resistance and decreased corrosion current density. The influence of Cl− concentration and temperature on corrosion rates followed similar trends. Rare earths improved corrosion resistance of EH36 steel.

15 - Optimal design of offshore jacket platform using enhanced colliding bodies optimization algorithm

Authors: Naser Shabakhty, Alireza Asgari Motlagh, Ali Kaveh Jacket platforms use a lot of materials, making their structural optimization important. The design optimization process is complex and slow, so efficient algorithms are needed. This research explores the Enhanced Colliding Bodies Optimization (ECBO) for a jacket platform, SPD19A, comparing it to the Genetic Algorithm (GA). The ECBO method improves the jacket's design by 15%, while GA achieves 11%, showing that ECBO is more effective at avoiding local optima.

16 - A Comparative Study on Hydrodynamic Responses of Floating Offhore Wind Turbine Platforms in Regular Waves.

Authors: Mir Tareque Ali, Md. Shariar Badon Floating Offshore Wind Turbine (FOWT) platforms are crucial for deep-sea conditions. This paper analyzes semisubmersible FOWT platforms in regular waves using Hydrostar software. It calculates wave excitation forces and motion responses in six degrees of freedom. Three base shapescircular, square, and hexagonalare studied, showing minimal impact on hydrodynamic behavior. Results may assist in FOWT design.

17 - Exploring the effects of ambient conditions on the cryogenic cooling times of offshore structures: Towards optimising ustainability and the decommissioning timescale.

Authors: Kenneth Bisgaard Christensen, Alireza Maheri, and M. Amir Saddiq This study looks at how ambient conditions affect cooling times for medium-carbon steel pipes during cryogenic processing, focusing on air velocity, ambient temperature, and cooling medium. Results show increased cooling times with certain conditions, validating cryogenic methods for carbon steel. The research emphasizes the significance of surface area and discusses the balance between cooling efficiency and costs. It aims to support Sustainable Development Goals by promoting eco- friendly cryogenic technologies for offshore structure decommissioning.

18 - Virtual Inertial Control of Small- and Medium-Sized Wind Turbines on Mobile Offshore Platforms with DC Microgrids.

Authors: Ruifang Zhang, Guoling Wang, Zhenyu Li, Fuqiao He, Chenghan Luo, and Wensheng Cao The renewable energy mobile offshore platform uses a mix of renewable energy and energy storage to support marine resource development. Due to the unpredictable nature of renewable energy, a virtual inertia control method for small- and medium-sized wind turbines is proposed to enhance stability. The method uses the wind turbine's mechanical inertia and is verified through experiments on a DC microgrid platform.

26 - Event-Triggered Neural Adaptive Distributed Cooperative Control for the Multi-Tug Towing of Unactuated Offshore Platform with Uncertainties and Unknown Disturbances.

Author: Shaolong Geng, Yulong Tuo, Yuanhui Wang, Zhouhua Peng, and Shasha Wang An event-triggered neural adaptive cooperative control is proposed for a towing system with uncertainties. It uses a neural network to manage disturbances and ensures desired drag force. A mechanism reduces communication needs and thruster frequency. The system's stability is confirmed, and the effectiveness is shown through simulations.

27 - Hydrodynamic performance of a submersible net cage integrated with an offshore platform

Authors: Zhenglin Tian, Hui Yang, and Hongjie Wen The integrated development of offshore platforms and net cages is important in ocean engineering. A composite structure is proposed, combining a submersible net cage with the steel pipe piles of an offshore platform to improve cost-effectiveness and use ocean resources better. A numerical model using OpenFOAM software assesses its hydrodynamic performance. The model is validated and used to study velocity variations and forces on the steel piles at different submerged depths.

35 - Reliability Analysis of a Four-legged Jacket Offshore Platform: A Case Study.

Authors: Hastuti, RW Prastianto, D M rosyid, F Syalsabila, M R Syarifudin Offshore oil and gas exploration needs reliable infrastructure, focusing on structural reliability. Designs often use fixed values, but random factors can vary. This research uses the Monte Carlo method to assess the reliability of a jacket platform in Indonesia, yielding high reliability scores of K = 0. 9883 and K = 0. 9963 for operating and extreme loads, respectively, indicating safety under analyzed conditions.

38 - Benchmark Dataset for Offshore Platform Motion Prediction and Its Applications.

Authors: Wenyin Pan, Xiaoxian Guo, and Xin Li Accurate prediction of offshore platform and ship motion is important for compensation devices and crew decisions. Machine learning models are replacing traditional methods due to simplicity and lower costs, but limited data complicates model training. This paper presents a motion dataset from over 400 offshore platform tests at Shanghai Jiao Tong University, divided for various applications. A new Convolutional Attention- based Long Short-Term Memory model improves motion prediction accuracy by 5–10% compared to classical models, proving the dataset’s reliability and the model's effectiveness.

39 - Optimization Simulation of Mooring System of Floating Offshore Wind Turbine Platform Based on SPH Method

Authors: Weibo Du, Peigang Jiao, Kangning Li, Jiaming Ding This paper utilizes the Smoothed Particle Hydrodynamics method to simulate the dynamic behavior of a floating offshore wind turbine mooring system in a complex marine environment. It introduces single-cable and double-cable systems in the model, using both first-order irregular and second-order regular waves for different conditions. The platform's performance is analyzed, yielding data on velocity and six degrees of freedom changes. The findings show that the optimized double- cable mooring system enhances the platform's vibration reduction capability.

40 - Numerical investigation on hydrodynamic response of a SPAR platform for offshore wind energy.

Authors: Arya Thomas, V.K. Srineash, and Manasa Ranjan Behera COP28 has urged governments to shift from fossil fuels to renewable energy like wind and solar power. This study investigates a SPAR-type Floating Offshore Wind Turbine’s responses under various wave conditions and mooring line setups. It examines how freak waves impact the turbine and analyzes wave-structure interactions using numerical modeling. The findings highlight that taut mooring configurations effectively stabilize the turbine during freak waves, contributing to understanding mooring performance under varying conditions..

41 - Study on the Prediction of Motion Response of Offshore Platforms Based on ResCNN-LSTM.

Authors: Feng Diao, Tianyu Liu, Franck Aurel Likeufack Mdemaya, and Gang Xu In a random sea environment, offshore platforms are affected by wind, waves, and currents, making their motion responses complex. This paper uses STAR-CCM+ to simulate offshore platform motion under regular and irregular waves. A predictive model combining convolutional and long short-term memory neural networks is developed to forecast motion responses, showing high accuracy with R² values over 0. 99 for regular waves and above 0. 4 for irregular waves. The study aims to improve decision-making for offshore platform operations.

46 - Applying Neural Networks to Predict Offshore Platform Dynamics

Authors: Nikolas Martzikos, Carlo Ruzzo, Giovanni Malara, Vincenzo Fiamma, and Felice Arena Integrating renewable energy with aquaculture on floating platforms promotes sustainable offshore infrastructure. A prototype tested in Italy provided insights into structural behavior. The study uses Artificial Neural Networks to predict mooring load changes. Several models were analyzed, achieving a Normalized Root Mean Square Error of 1. 7–4. 7%. Results show machine learning's potential in ocean systems management.

47 - OC6 Phase IV: Validation of CFD Models for Stiesdal TetraSpar Floating Offshore Wind Platform

Authors: Hannah Darling, David P. Schmidt, Shengbai Xie, Jasim Sadique, Arjen Koop, Lu Wang, Will Wiley, Roger Bergua Archeli, Amy Robertson, Thanh Toan Tran Floating offshore wind turbine (FOWT) technology is new and relies on modeling tools for development. The OC6 project aims to verify these tools. The Stiesdal TetraSpar platform was simulated with CFD under OC6 conditions, showing good predictions of wave response but some damping issues due to uncertainties. The study provides insights into achieving reliable results.

48 - Study on Motion Response Prediction of Offshore Platform Based on Multi-Sea State Samples and EMD Algorithm.

Authors: Tianyu Liu, Feng Diao, Wen Yao, Franck Aurel Likeufack Mdemaya, and Gang Xu Offshore platforms must handle changing marine environments, requiring analysis of their motion under various conditions. This study uses STAR-CCM+ software to assess platform responses to different wave directions and heights. The method enhances forecasting of offshore structures' dynamic responses, supporting safer and more productive maritime operations.

53 - Design for additive manufacturing of topologically optimized air manifold

Author: Nikolaos Kladovasilakis Topology optimization is used in mechanical design for lightweight and cost-effective solutions. This study outlines a workflow for redesigning a low-pressure air manifold using advanced design. Iterative finite element analyses removed excess material and improved structural integrity, resulting in a design 76% lighter than the original, costing under €5 per item. This workflow can apply to various 3D-printed mechanical parts in different industries.

54 - Structural Effectiveness of Fixed Offshore Platforms with Respect to Uniform Corrosion.

Authors: Abubakar O. Salihu , Kolawole Abejide, Olugbenga S. Abejide, Jibrin M. Kaura, Ibrahim Aliyu, Kehinde Adeshina, Olugbenga S. Abejide This study evaluates the effectiveness of fixed offshore platforms under complex marine conditions. Using Finite Element Analysis and Monte Carlo’s reliability method, it assesses how corrosion and environmental loads affect structural performance. Results show high stress in beam and column connections. Choosing high-grade steel and larger cross-sections can enhance durability and safety. The findings underscore the need to consider material properties, connections, and loading in design to improve offshore platform reliability.

55 - Effectiveness of deck-isolation and viscous dampers supplement on enhancing seismic performance of offshore jacket platforms

Authors: S. Dashti, K. Tarbali, C. Zhou, J.G. Chase Offshore structures used for oil production are adapting for renewable energy. This study assesses the seismic performance of a typical offshore jacket platform and two modified versions with isolation systems. Ground motion ensembles are selected based on the site’s seismic hazard. Results show significant reductions in displacement, acceleration, and base shear with the application of a specific damper.

56 - Local Structure Optimization Design of Floating Offshore Wind Turbine Platform Based on Response Surface Analysis.

Authors: Yajun Ren, Mingxuan Huang, Jungang Hao, Jiazhi Wang, Shuai Li, Ling Zhu, Haisheng Zhao, and Wei Shi The floating platform is essential for the floating offshore wind turbine (FOWT), with its internal design being crucial for safe operation. The study parameterized the local model, created a response surface model through an orthogonal test, and optimized it using a gradient descent algorithm. Safety calibration confirmed the internal structure arrangement. The optimized model shows a 22. 12% reduction in maximum stress without changing mass and centroid, enhancing safety and offering useful insights for FOWT platform design and construction.

57 - Methodological proposal for satellite communication on offshore self-elevating platform.

Authors: Ricardo A. Barrera Cámara, José R. González - Reda, Alejandro Fuentes-Penna The use of information and communication technologies improves work and communication, but challenges exist in remote areas. The goal is to implement a satellite communication system for offshore platforms using VSAT technology, following a tested methodology.

58 - Multi-Antenna GNSS–Accelerometer Fusion Attitude Correction Algorithm for Offshore Floating Platform Displacement Monitoring.

Authors: Xingguo Gao, Junyi Jiang, Guoyu Xu, Zengliang Chang, and Jichao Yang A new attitude correction algorithm was proposed to improve GNSS displacement monitoring on offshore floating platforms by blending multi-antenna GNSS and an accelerometer using Kalman filtering. The method was tested successfully, enhancing accuracy and compensating for low sampling rates.

59 - Synergic sensing of light and heat emitted by offshore oil and gas platforms in the South China Sea.

Authors: Yujia Qiu, Xiao-Ming Li, Lin Yan, and Zhongzhong Chen The growing demand for oil and gas requires customized monitoring of platforms. Remote sensing is effective, but has limitations. The SDGSAT-1 offers high-resolution imaging and has been used to detect gas flaring at 113 active platforms in the South China Sea.

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09 - Research on the failure mechanism of non-metallic oil pipeline flange

Authors: Yu Weng, Dejun Li, Shuxuan Jiang, Shuang Yang, Gang Wu, and Zhian Deng Fiberglass flanges are increasingly used in oil field transportation pipelines because they resist corrosion and are easy to shape. However, issues like anisotropy and local discontinuity can occur. Research was conducted on a fiberglass flange joint from an oilfield sewage pipeline after discovering cracks and leaks. Tests measured the mechanical performance under various loads. A finite element model was created to analyze flange damage under different conditions. Results showed bolt holes are likely to fail due to stress concentrations. It's suggested that bolt pre-tightening should stay below 400,000 N and bending moments should not exceed 200 N·m.

13 - Limit state equation and failure pressure prediction model of pipeline with complex loading

Author: Ming-ming Sun, Hong-yuan Fang, Nian-nian Wang, Xue-ming Du, Hai-sheng Zhao, & Ke-Jie Zhai This study proposes a limit state equation for steel pipes under various loads, based on a three-dimensional pipeline stress model with complex load coupling. The equation is based on a unified yield criterion and can be used to assess failure pressure in pipelines with complex loads. The evaluation model can be used as a theoretical solution for selecting appropriate yield criteria based on load condition differences.

14 - Uncoupled multimodal wave reflection from guide termination with different flanges: Experimental and numerical investigation

Authors: David Marx, Florent Margnat, Hélène Bailliet, Christian Prax , Zhiping Qiu, and Jean- Christophe Valière This study examines the reflection of propagating modes at the exit of a cylindrical acoustic wave guide, extracting plane mode and several azimuthal higher modes. The uncoupled reflection coefficients of each mode are obtained using two microphonic antennas. The study also examines reflection at the open end of the guide for different terminations: without flange, with a finite fl ange, and with an infinite rigid fl ange. Results are compared with theoretical predictions.

21 - Investigation of Pipeline CO2 Leakage and Diffusion on Offshore Platforms Based on Numerical Simulation

Authors: Yang Cao, Tao Liu, Guangchun Song, Wei Zhou, Hui Han, Yuxing Li, Qihui Hu, and Ruidong Jing This study focuses on the leakage and diffusion characteristics of CO2 in pipeline transportation on offshore platforms. It involves building physical and numerical models, conducting simulations, and analyzing temperature and CO2 concentration distributions. The study also examines the influence of leakage direction and provides suggestions for staff evacuation. The research aims to provide guidance for the safe operation of offshore CO2 storage platforms.

22 - Review of "cold shock" cases in operation of loop heat pipes and related thermal instabilities

Authors: L Ivanovskis, and D Mishkinis Loop Heat Pipes (LHP) are passive heat transfer devices used in spacecraft thermal control and terrestrial applications. However, they can experience thermal instabilities and partial or complete wick dryout during power-up steps or rapid condenser cooling changes. These instabilities are often overlooked in literature and often trade performance for robustness. Grid-like multievaporator LHPs with multiple parallel connections can increase heat leaks into compensation chambers. Understanding the "cold shock" phenomenon is crucial for developing technical measures for LHP designs.

25 - Effect of seawater salinity, pH, and temperature on external corrosion behavior and microhardness of offshore oil and gas pipeline: RSM modelling and optimization

Author: Imran Mir Chohan, Azlan Ahmad, Nabihah Sallih, Naraindas Bheel, Waleligne Molla Salilew, & Abdulrazak H. Almaliki This document examines the impact of seawater parameters on the corrosion behavior and microhardness of offshore oil and gas carbon steel pipes. Immersion tests and field-emission scanning electron microscopy analysis were conducted. Results showed that increased salinity reduced corrosion rate by 28%, while pH variations increased it by 42.54%. The temperature was the most significant parameter, causing an increase in corrosion rate and a reduction in microhardness.

30 - Research on calibration method for flange-type apparatus to Measure Water Permeability of Concrete

Authors: Xiaodong Deng, Yanxiang Fu, Jing Yuan Yang Xu, and Tingting Ren Concrete's water permeability is crucial for building structure stability and durability. A new calibration method is proposed for flange-type apparatuses to measure water permeability. The method connects standard pressure measuring devices to calibrated apparatuses, ensuring sealing performance and operational safety. A host computer software is also presented for data recording and analysis. Experimental verification confirmed that this method can simultaneously calibrate indication error and set pressure retention error, improving on-site calibration accuracy.

34 - Structural Capacity Estimation of Subsea Flanges Using Various Codes and Standards

Authors: Kumarswamy Karpanan, Finn Kirkemo, Kannan Subramanian This paper presents a subsea standard flange design and analyses it against various codes and standards in the oil and gas industry. This flange, designed to withstand up to 20 ksi operating pressure, is exposed to high bending, shear, and torsional loads. Its capacity is presented in a chart and compared against the existing flange capacities. The paper also discusses the conservatism and limitations in each code and standard for flange design and suggests analysis procedures for designing Other-End Connections.

36 - Analysis of Factors Affecting the Seismic Performance of Widened Flange Connections in Mid-Flange H-Beams and Box Columns

Authors: Tigist Demssice Gemechu, and Linfeng Lu This study explores the seismic performance of connections with widened beam-end faces in mid-fl ange H-beams and box columns. Finite element modeling shows that widened beam-end faces improve bending capacity and ductility by relocating the plastic hinge, enhancing seismic resilience. Key findings include optimal design parameters for effective plastic hinge development and improved structural performance, emphasizing geometric optimization over material-based enhancements.

37 - Failure analysis on cracking and leakage of 304 stainless steel flange in petrochemical butyl device

Authors: Lei Cheng, Chenyang Du, Xiaowei Li, Baolin Liu, and Guoju Cui A 304 stainless steel flange of an ethylene pipeline in China was found to be cracking and leaking during a pressure test. The failure was attributed to the flange's carbon content exceeding standard, carbide precipitation, sensitization, and reduced intergranular corrosion resistance. The failure was also triggered by high stress in corrosive media.

43 - Global Buckling Strength of Girts with Inner Flange in Compression

Authors: Huy Hoang Vu, Quoc Anh Vu, Cao Hung Pham This paper aims to improve the lateral-torsional buckling strength of cold-formed, channel-section wall girts subjected to leeward wind loads. It identifies the cross- sectional dimensions that affect this strength, as the inner flange's strength is significantly lower than the outer flange's due to material waste. A parametric study on three typical channel cross-sections revealed that increasing flange width improves flexural strength without considering the bracing effect of sheathings, while increasing cross-section thickness improves strength considering sheathing effect.

44 - Large - Scale Physical Model Test on the Influence of Landslide Hazards on Oil and Gas Pipeline Bending

Authors: Xianjie Hao, Yuguang Chen, Yulong Chen, Daiyu Gao, Qian Zhang, Yinpen Zhao, Fan Cui, Honglan Zhang This study investigates the impact of landslide geological disasters on oil and gas pipelines, focusing on their deformation characteristics under different landslide dip angles. Experiments were conducted at different dip angles, monitoring changes in stress, strain, and soil displacement. Results showed that pipeline bending can be divided into slow-speed, constant-speed, and accelerated-speed stages. Tensile strain and compressive strain are produced back and facing the landslide direction. The study provides a pipeline deformation law, aiding in monitoring and early warning of pipeline landslide disasters.

33 - Optimizing pipeline assembly: a novel model for predicting assembly pose considering clamp constraints

Authors: Jia Cheng, Bin Gu, Haidong Yu, and Chang Gao This article presents an optimization model designed to improve the performance of pipeline assembly by accurately predicting the assembly pose while ensuring that clamp constraints are met. The model quantitatively assesses joint defects and assembly interference and establishes a mapping relationship between the assembly pose and assembly interference. It leverages a digital fitting model to enhance the fit between the pipeline and clamps, employing reinforced particle swarm optimization with an adaptive inertia weight. The findings indicate that the model effectively minimizes joint defects and enhances assembly efficiency, facilitating a one-time assembly process.

Authors: Deokhee Won, Jihye Seo, Osoon Kwon, Hae- Young Park, and Hyoun Kang Offshore wind power foundations include floating, tripod, jacket, monopile, and gravity-based types, with tripod and jacket designs requiring precise construction. Two installation methods exist: post-piling, which is slower but avoids specialized equipment, and pre-piling, which uses a seabed-anchored template for improved precision. This study introduces a new underwater pre-piling template, analyzing construction precision based on wave conditions, current speed, winch speed, and vessel type. Results indicate wave conditions, winch speed, and vessel type significantly impact precision.

20 - Study on the permeability characteristics of different geotextiles under weft and warp stretching

Authors: Xiaolei Man, Jing Liu, Xueli Liu, Chengbin Lu, Yun Chen Geotextiles, widely used in water conservancy engineering as anti-filtration materials, have water permeability performance under stressed states that remains insufficiently understood. A unidirectional rheological head infiltration test, conducted using a custom apparatus, examined the impact of unidirectional stretching on geotextile permeability. The study concludes that geotextile thickness significantly influences its permeability characteristics.

Authors: Shuangqi Kang, Xiangdong Kong, Jin Zhang, and Ranheng Du Jet pipe servovalve design and analysis traditionally rely on linear models, though nonlinear factors exist in these electromechanical-hydraulic systems. The study derives a linear rotation equation for the armature assembly and a linear flow equation for the control cavity, then incorporates nonlinear hydraulic reaction forces to establish a nonlinear dynamic equation for the main spool. Using MATLAB (R2016a), the nonlinear model is numerically analyzed, including equilibrium point calculations, phase portrait plotting, and bifurcation analysis (Hopf and period-doubling).

12 - Assessment of the locational potential of floating offshore wind energy in South Africa

Author: Kubiat Umoh, Abbas Hasan, Amangeldi Kenjegaliev, and Ayman Al-Qattan Expanding floating wind to new markets supports emission reductions and requires thorough assessments. South Africa, with high FOW potential but limited development, was studied via a three-phase approach: evaluating technical drivers/barriers, GIS analysis (ArcMap 10.8) excluding unsuitable sites, and capacity estimation. Results show 2% of its EEZ (246,105.4 km²) suitable for up to 142.61 GW. Western Cape has highest potential (80.52 GW), yet Eastern Cape is best for early projects due to grid access, low traffic, and ports. Future techno-economic assessments are recommended.

31 - Dynamic Analysis of Crane Vessel and Floating Wind Turbine during Temporary Berthing for Offshore On-Site Maintenance Operations

Author: Jinkun Sh, Mingfeng Hu, Yifan Zhang, Xiaodong Chen, Sheng Yang, Thiago S. Hallak, and Mingsheng Chen With the expansion of floating wind turbines in deep-sea environments, jack-up vessels face maintenance limitations due to water depth constraints, highlighting the need for floating cranes. However, dynamic interactions between the crane and turbine under wave and wind forces, along with complex mooring configurations, pose stability challenges during maintenance. To address this, a method simulating the berthing of a floating offshore wind turbine (FOWT) to a floating crane was proposed. Frequency- and time- domain simulations using ANSYS-AQWA software confirmed the feasibility and dynamic efficiency of this approach.

32 - Simulation and Calculation of Temperature Field and Current- Carrying Capacity of Power Cables under Different Laying Methods

Authors: Yongjie Nie, Daoyuan Chen, Shuai Zheng, Xiaowei Xu, Xilian Wang, and Zhensheng Wu As floating wind turbines expand into deep-sea environments, traditional jack-up vessels face limitations in water depth for maintenance. Floating cranes offer a solution, but their dynamic coupling with turbines under waves and wind introduces stability challenges. A proposed method involves physically connecting the floating crane to the turbine, simulating berthing. Using ANSYS-AQWA simulations, this approach demonstrated feasibility by reducing crane tip movement (X-, Y-, and Z- directions) by over 30%, suggesting that properly constrained floating cranes could enable stable offshore maintenance operations for floating offshore wind turbines (FOWTs).

49 - A Tank Experiment of the Autonomous Detection of Seabed- Contacting Segments for Submarine Pipelaying Operations

Authors: Bo Wang, Jie Wang, Chen Zheng, Ye Li, Jian Cao, and Yueming Li Harsh seabed conditions hinder underwater ROV pipeline segment detection due to weak features and light attenuation. We propose cascade attention and prefusion modules in a CNN: the former samples features non- convolutionally for structure-channel interaction, while the latter fuses multi-stage backbone maps for richer spatial- semantic information. Experiments on underwater pipeline datasets and tank tests confirm improved detection, boosting the best model's AP by 6.3% and mIoU by 3.8%.

50 - An MBD based systematic approach of accommodation module building with integrity

Author: Jincheng Wang, Huilong Ren, Niansheng Chu Leading shipyards use integrated hull construction, outfitting, painting, and unified design-production- management to shorten build periods and boost efficiency. Accommodation module integrity varies widely, with few achieving high levels. This paper presents an MBD-based systematic approach: plan facilities, lean processes, and integrity standards from a preliminary 3D model, finalize it, then use the model as the sole resource for execution, inspection, and evaluation. Shanghai Waigaoqiao delivers ~30 fully integrated modules yearly within 100 days, filling IHOP/MBD theoretical gaps and guiding shipyards to improve effectiveness.

51 - Floater Assembly and Turbine Integration Strategy for Floating Offshore Wind Energy: Considerations and Recommendations

Author: Glib Ivanov, and Kai-Tung Ma To meet rising demand for cost-effective floating offshore wind turbines (FOWTs), this study examines assembly strategies for 15 MW FOWTs with semi-submersible floaters using Taiwan’s port infrastructure as a case study. It evaluates on-quay assembly against remote construction with towing, analyzing port operations, crane requirements, and procedures. Findings show that on- quay assembly at a major port is both feasible and cost- effective when port infrastructure and logistics are optimized, offering actionable insights for scaling FOWT projects.

52 - Dynamic analysis of crane barge during vibratory extraction of offshore monopile foundation

Author: Soheil Salahshour, Zhiyu Jiang, Muk Chen Ong, Bjørn Skaare This study simulates the vibratory extraction of an offshore wind turbine monopile foundation using a crane barge. A coupled numerical model is developed to analyze the dynamic interaction between the monopile and barge, incorporating high-fidelity soil resistance and vibro- hammer forces via Dynamic Link Libraries (DLLs). Time- domain simulations assess the barge's motion and lifting wire tension under both calm water and wave conditions, while also evaluating the dynamic positioning system's impact. The findings enhance understanding of offshore wind turbine decommissioning in marine environments.