Abstract
Under extreme climatic conditions, especially wind-rain coupling, roof shutters' mechanical behavior is
complex and under-researched. To ensure their safe application in metal roof systems, this study investigates their
stress distribution and dynamic response under wind and rain. Taking roof shutter engineering as background, it
analyzes mechanical properties under different wind-rain effects and compares natural frequencies of shutters with
varying wind-rain effects and geometric dimensions. Results show shutter stress increases linearly with wind speed
and rain intensity; rain intensity and wind speed maximally increase stress distribution by 49.2% and 18.2%,
respectively. Wind-driven rain impacts far more than wind or rain alone. Wind-rain effects and structural-geometric
factors influence shutter natural frequency by up to 58.6% and 23.2%. Comparing dynamic responses under different
boundaries reveals constraints significantly affect natural frequency and damping; under 4-edge constraint, average
damping ratio rises by 85.7%. Wind-driven rain and geometric size have a significant superposition effect on
mechanical properties and dynamic response, with boundary conditions's influence on damping ratio non-negligible.
Address
Laixiu Cheng:School of Resources and Architecture Engineering, Gannan College of Science and Technology, Ganzhou Jiangxi 341000, China
Mingming Wang:Guangdong Provincial Academy of Building Research Group Co., Ltd. Guangzhou 510599, China
Yupeng Dong:School of Resources and Architecture Engineering, Gannan College of Science and Technology, Ganzhou Jiangxi 341000, China
Cholap Chong:School of Civil Engineering and Transportation, Foshan University, Foshan, Guangdong 528225, China
Danqing Song:1)State Key Laboratory of Subtropical Building and Urban Science, School of Civil Engineering and
Transportation, South China University of Technology, Guangzhou, Guangdong 510640, China
2)Nanjing University (Suzhou) High-tech Institute, Suzhou 215000, China
Xiaoli Liu:State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua
University, Beijing, 100084, China
Abstract
This study investigates dust dispersion and ventilation strategies in tunnel drilling and blasting operations
at Chongqing East Station using computational fluid dynamics (CFD) simulations based on a Eulerian-Lagrangian
framework and the Realizable k-ε turbulence model. The Discrete Phase Model (DDM) incorporating two-way
coupling and a stochastic random walk method was employed to accurately trace dust particle trajectories under
turbulent conditions. The key innovation of this work lies in analyzing multi-channel tunnel ventilation and dust
transport specifically at the critical breathing zone height for tunnels with significant cross-sectional variations. An
analytical model was developed to predict dust concentration levels 20 minutes after ventilation initiation. The CFD
model was rigorously validated against field data, showing high predictive accuracy with velocity errors within
0.0749 m/s and dust concentration deviations between 0.1403 and 0.5448 mg/m3. Results demonstrate that the cross
sectional size significantly influences ventilation efficiency, with optimal ventilation velocities identified as 6 m/s, 10
m/s, and 14 m/s for the three tunnel lines, ensuring dust concentrations fall below the safety threshold of 2 mg/m3
within 20 min. The proposed analytical model agrees well with the CFD simulations for various ventilation velocities
and tunnels. The proposed analytical model agrees well with the CFD simulations for various ventilation velocities
and tunnels. The findings provide practical insights for identifying the minimum required ventilation velocity to
achieve safety compliance in tunnel construction environments.
Key Words
CFD; dedusting time; discrete particle model; dust ventilation; tunnel drilling and blasting
Address
Weicheng Hu:1)State Key Laboratory of Safety and Resilience of Civil Engineering in Mountain Area, East China
Jiaotong University, Nanchang, 330013, China
2)School of Civil Engineering, Southeast university, Nanjing, 210096, China
Qiming Luo:China Railway 11th Bureau Group Co., Ltd., Wuhan, 430061, China
Pengfei Zhang:State Key Laboratory of Safety and Resilience of Civil Engineering in Mountain Area, East China
Jiaotong University, Nanchang, 330013, China
Biao Nie:State Key Laboratory of Safety and Resilience of Civil Engineering in Mountain Area, East China
Jiaotong University, Nanchang, 330013, China
Jun Wu:Zhejiang Jiangnan Project Management Co., Ltd., Hangzhou, 310007, China
Hua-Peng Chen:State Key Laboratory of Safety and Resilience of Civil Engineering in Mountain Area, East China
Jiaotong University, Nanchang, 330013, China
Abstract
This paper proposes a semi-active control system employing a magnetorheological gyro-mass damping
(MGMD) system governed by a model predictive control (MPC) algorithm, which effectively suppresses tower
vibrations and constrains the working stroke. The MGMD system is designed by integrating a magnetorheological
damping component (capable of real-time damping adjustment via the MPC algorithm) into a gyro-mass damper
(providing mass amplification effects). After optimizing the MGMD system's stiffness and damping parameters for
various lead lengths and mass ratios via the particle swarm optimization (PSO) algorithm, analysis of the results
indicated that optimal vibration suppression was achieved at smaller lead lengths, with minimal performance variation
across mass ratios. Finally, a comparative analysis of vibration suppression performance is conducted between the
optimized MGMD system installed at the top of the tower and conventional tuned mass dampers (TMDs), utilizing
the NREL 5-MW OC3-Hywind spar floating offshore wind turbine (FOWT) model. The results indicate that, under
four typical load cases with the optimal lead length of 5 mm, the MGMD system achieves a peak suppression rate of
81.3% to 93.0% for the power spectral density of tower top fore-aft deformation, while reducing the working stroke
by 70.01% to 78.63% compared to the conventional TMDs. The proposed MGMD system significantly reduces
vibration under typical load cases, demonstrating its substantial potential for enhancing the operational safety and
longevity of spar FOWTs.
Key Words
floating offshore wind turbine; gyro-mass damper; magnetorheological damper; model predictive
control; particle swarm optimization; tower vibration suppression
Address
Rongye Zheng:1)School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou, China
2)Fujian Provincial University Engineering Research Center of Marine Engineering Equipment Design and
Manufacturing, Fuzhou, China
Guojun Qiu:School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou, China
Junjie Gan:School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou, China
Jiahuan Lin:School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou, China
Jun Zhang:1)School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou, China
2)Fujian Provincial University Engineering Research Center of Marine Engineering Equipment Design and
Manufacturing, Fuzhou, China
Abstract
Hurricane Maria made landfall in Puerto Rico with maximum sustained winds of 69 m/s (155 mph),
causing widespread damage to a variety of structures, including guide signs supported by breakaway I-section posts.
Previous studies have estimated that the hurricane produced 3-second gust wind speeds of up to 69 m/s (155 mph) at
10 m (33 ft) above ground for flat, open terrain on the island. The objectives of this research are to estimate the wind
speeds that caused damage to guide signs mounted on breakaway I-section posts and to identify design and
construction improvements to enhance their wind performance. Field surveys were conducted along major highways
in Puerto Rico to locate damaged guide signs, inspect the structures, and document their modes of failure. Three
primary failure mechanisms were identified: foundation failure, fuse plate slippage, and fuse plate fracture. Three
case studies involving fuse plate fracture were selected for detailed analysis, for which field measurements were
collected. The structures were then analyzed to estimate the wind pressures associated with the observed failures,
which were subsequently used to back-calculate the corresponding 3-second gust wind speeds at 10 m (33 ft) height
for open terrain. The results indicate that the peak gust wind speeds experienced at the study sites during Hurricane
Maria may have exceeded values previously estimated for flat terrain conditions. Based on the identified failure
mechanisms, recommendations are proposed to improve the wind resistance and resiliency of guide signs supported
by breakaway I-section posts.
Key Words
back-calculation of wind speed; hurricane gust wind speeds; post-event damage analysis;
roadside signs; wind loads
Address
Hector J. Cruzado:Department of Civil & Environmental Engineering and Land Surveying,
Polytechnic University of Puerto Rico, 377 Ponce de Leon, Ave., San Juan, PR, 00918, USA
Gustavo E. Pacheco-Crosetti: Department of Civil & Environmental Engineering and Land Surveying,
Polytechnic University of Puerto Rico, 377 Ponce de Leon, Ave., San Juan, PR, 00918, USA
Abstract
The aerodynamic performance of high-speed trains under heavy rainfall has attracted increasing attention.
Previous studies mainly focus on airflow and wind loads, with limited consideration of rain fields and rain-induced
loads. In this study, a three-car high-speed train is employed to investigate the airflow field, rain field, and associated
wind and rain loads. The airflow field is simulated using an Eulerian approach and validated by wind tunnel
experiments, while the rain field is modeled using a Lagrangian framework and validated based on raindrop impact
mass. The two fields are coupled through a momentum exchange method, and a rain load model is further developed
based on impact experiments. The results indicate that heavy rainfall not only introduces significant impact forces but
also deteriorates aerodynamic performance. The total longitudinal wind and rain loads increase with both train speed
and rainfall intensity. The vertical loads on the head train and middle train increase with both parameters, whereas those
on the tail train increase with train speed but decrease with rainfall intensity. Moreover, the longitudinal rain load
exhibits a nonlinear dependence on rainfall intensity, while the vertical rain load shows a linear relationship.
Key Words
high-speed train; rainfall intensity; rain load; wind load
Address
Xugao Sheng:College of Civil Engineering and Architectural, Beijing Jiaotong University, Beijing 100044, China
Jun Mao:College of Civil Engineering and Architectural, Beijing Jiaotong University, Beijing 100044, China
Mengge Yu:College of Mechanical and Electrical Engineering, Qingdao University, Qingdao 266071, China
open access
