http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Linearized analysis of the internal pressures for a two-compartment building with leakage
Xianfeng Yu,Ming Gu,Zhuangning Xie 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.28 No.2
The non-linear equations governing wind-induced internal pressures for a two-compartment building with background leakage are linearized based on some reasonable assumptions. The explicit admittance functions for both building compartments are derived, and the equivalent damping coefficients of the coupling internal pressure system are iteratively obtained. The RMS values of the internal pressure coefficients calculated from the non-linear equations and linearized equations are compared. Results indicate that the linearized equations generally have good calculation precision when the porosity ratio is less than 20%. Parameters are analyzed on the explicit admittance functions. Results show that the peaks of the internal pressure in the compartment without an external opening (Compartment 2) are higher than that in the compartment with an external opening (Compartment 1) at lower Helmholtz frequency. By contrast, the resonance peak of the internal pressure in compartment 2 is lower than that in compartment 1 at higher Helmholtz frequencies.
Xianfeng Yu,Zhuangning Xie,Ming Gu 대한토목학회 2019 KSCE Journal of Civil Engineering Vol.23 No.9
After considering the combination of internal pressure and external pressure acting on the roof, the coupling dynamic equations to describe the relationship between wind-induced internal pressure and flexible roof are reviewed and further refined. The internal pressure responses and the first order modal response of a flexible roof can be evaluated by the coupling equations. Wind tunnel test was carried out on an aeroelastic roof model which was treated as a single-degree-of-freedom system. Three factors, approaching wind velocities at the center of the dominant opening, acceleration responses at dominant opening areas and background leakages, which have effects on roof acceleration responses were studied. On this basis, the effectiveness and calculation precision of the coupling equations were verified. Results show that the root-mean-square (RMS) value of roof acceleration increases with the increase of the approaching wind velocity and dominant opening area, and in background leakage decreases. Meanwhile, theoretical calculation values of RMS internal pressure and RMS acceleration response corresponding to the first order modal of flexible roof agree well with the wind tunnel experimental data.
Aerodynamic measurements of across-wind loads and responses of tapered super high-rise buildings
Deng, Ting,Yu, Xianfeng,Xie, Zhuangning Techno-Press 2015 Wind and Structures, An International Journal (WAS Vol.21 No.3
A series of wind tunnel tests were conducted on tapered super high-rise buildings with a square cross section by applying synchronous pressure measurement technology. The effects of global strategy of chamfered modification on aerodynamic loads and wind-induced responses were investigated. Moreover, local aerodynamic strategies of opening a ventilation slot in the corner of equipment and refuge floors were carried out. Results show that the global strategy of tapered elevation increased the vortex shedding frequency, but reduced vortex shedding energy, leading to reduction of across-wind aerodynamic loads and responses. Chamfered modification suppressed the across-wind vortex shedding effect on tapered buildings. Opening the ventilation slot further suppressed the strength of vortex shedding and reduced the residual energy related to vortex shedding in aerodynamic loads of chamfered buildings. Finally, the optimized locations of local aerodynamic strategies were suggested.
Aerodynamic measurements of across-wind loads and responses of tapered super high-rise buildings
Ting Deng,Xianfeng Yu,Zhuangning Xie 한국풍공학회 2015 Wind and Structures, An International Journal (WAS Vol.21 No.3
A series of wind tunnel tests were conducted on tapered super high-rise buildings with a square cross section by applying synchronous pressure measurement technology. The effects of global strategy of chamfered modification on aerodynamic loads and wind-induced responses were investigated. Moreover, local aerodynamic strategies of opening a ventilation slot in the corner of equipment and refuge floors were carried out. Results show that the global strategy of tapered elevation increased the vortex shedding frequency, but reduced vortex shedding energy, leading to reduction of across-wind aerodynamic loads and responses. Chamfered modification suppressed the across-wind vortex shedding effect on tapered buildings. Opening the ventilation slot further suppressed the strength of vortex shedding and reduced the residual energy related to vortex shedding in aerodynamic loads of chamfered buildings. Finally, the optimized locations of local aerodynamic strategies were suggested.
Jingwei Zhang,,Nabil Ebraheim,Ming Li,Xianfeng He,Jiayong Liu,Limei Zhu,Yihui Yu 대한정형외과학회 2015 Clinics in Orthopedic Surgery Vol.7 No.1
Background: The locking plates are often used for internal fixation of closed tibial fractures. The use of a locking plate as an externalfixator is still controversial, particularly for closed fractures. The purpose of this study is to evaluate the results of externalfixation using the femoral less invasive stabilization system (LISS) plate in proximal metaphyseal fractures of the tibia. Methods: We prospectively evaluated 35 patients (26 males and 9 females) with a mean age of 42 years (range, 21 to 62 years)who presented with fresh tibial proximal metaphyseal fractures. According to the AO Foundation and Orthopaedic Trauma Association(AO/OTA) classification, the fractures were identified as type 41-A2 in 18 cases and type 41-A3 in 17 cases, including 25closed fractures and 10 open fractures. The femoral LISS plate was used to fix these fractures, which was placed on the anteromedialaspect of the tibia as an external fixator. The mean follow-up period was 18 months (range, 13 to 22 months). Results: All fractures healed in a mean time of 14 weeks (range, 10 to 20 weeks). There was no case of nonunion, deep infection,and loosening of screws and plates. One month after the appearance of cortical bridging on biplanar radiographs, the locking platewas removed within 3 minutes in the clinic without any difficulty. According to the Hospital for Special Surgery (HSS) knee scoringsystem and American Orthopaedic Foot & Ankle Society (AOFAS) ankle scoring system, the mean HSS score was 91 (range, 85 to100) and 98 (range, 93 to 100), and the mean AOFAS score was 94 (range, 90 to 100) and 98 (range, 95 to 100) at 4 weeks postoperativelyand final follow-up, respectively. Conclusions: For proximal metaphyseal fracture of the tibia, external fixation using the femoral LISS plate is a safe and reliabletechnique with minimal complications and excellent outcomes. Its advantages include ease of performing the surgery, use of a lessinvasive technique, and convenience of plate removal after fracture healing.
Experimental Investigations on VIV of Bridge Deck Sections: A Case Study
Zeng-shun Chen,Si-meng Liu,Xianfeng Yu,Cun-ming Ma,Lei Liu 대한토목학회 2017 KSCE Journal of Civil Engineering Vol.21 No.7
In this paper, the Vortex Induced Vibrations (VIVs) of bridge deck sections of the Hong Kong-Zhuhai-Macao Bridge were investigated experimentally. Aeroelastic tests for the bridge deck of two scale ratios (1:20 model and 1:50 model) under different wind attack angles, wind speeds, and damping ratios were performed. Accessory and windbreak effects on the VIVs of the bridge deck were also carried out. The experimental results show that the accessory and windbreak tend to enlarge the VIVs of the bridge deck. Furthermore, the most unfavorable wind attack angle is 5o. At this attack angle and low damping ratios, the VIVs of the bridge deck are significant and much larger than the allowable value. In addition, the VIVs of the bridge deck decrease with increasing the damping ratios (Particularly, at large damping ratios, the VIVs were well suppressed). This study provides a guideline for the designs of long span flexible bridges on suppressing the VIVs of the bridges.