scholarly journals Technique for Analyzing Relationship Between Unbalanced Load and Structural Deterioration in Outside Facilities

2021 ◽  
Keyword(s):  
Maximum Load ◽  
Small Error ◽  
Wind Pressure ◽  
Private Land ◽  
Simulation Accuracy ◽  
Spring Element ◽  
Structural Deterioration ◽  
Utility Poles ◽  
Conventional Solution ◽  
Unbalanced Loads

Abstract. In order to provide telecommunication and FTTH services, NTT have installed so many facilities such as utility poles and optical cables. The number of poles is about 11.8 million and the total length of all installed cables is about 2.3 million km. These facilities are now maintained and inspected visually by on-site maintenance staff at great expense. Therefore, we are researching a novel outside-facility renovation technology that increases cost-effectiveness by ensuring the long-term safe use of facilities. When a utility pole is newly constructed, it is designed under the assumption of a maximum load such as wind pressure being applied to the pole via cables and auxiliary attachments. However, the loads can become imbalanced when the guy wire cannot be tensioned as they cross private land or when there are obstacles, etc. We call this condition that unbalanced loads occur. Unbalanced loads are one of the key reasons for the structural deterioration of utility poles. After the deterioration occurs, the risk of pole collapse increases, because deflection and inclination are generated and finally the cracks propagate until collapse. The conventional solution is to replace the damaged pole. However, in many cases, the loads are created by other contiguous poles, so unbalanced loads occur again. Therefore, we are developing a method that can identify the reason by regarding sets of utility poles as "facility systems" and analyzing unbalanced loads quantitatively by FEM. In our research, simulation accuracy is improved by determining the quantitative differences obtained by comparing the calculated results obtained by FEM with measured values obtained by using a reaction wall. The simulations of structural degradation due to unbalanced loads taking into account the deformation of cables due to wind velocity and air temperature in addition to various material properties such as hysteresis and the sectional model of the utility poles. In addition to the above, the effect of soil is considered as a spring element, and the analysis involves the elements of horizontal spring (Kxi, Kzi) and vertical spring (Kv). While the calculated and the measured values show good agreement, there is some small error. This error is considered to be due to the influence of parameters such as tensile and compressive strength, and we aim to improve the simulation accuracy by considering these effects in the future.

scholarly journals Novel Outside-Facility Renovation Technology to Improve Cost-Effectiveness by Long-Term Safe Use

2021 ◽  
Keyword(s):  
Cost Effectiveness ◽  
Significant Risk ◽  
Structural Deterioration ◽  
Utility Pole ◽  
Utility Poles ◽  
Improve Cost Effectiveness ◽  
Unbalanced Load ◽  
Unbalanced Loads ◽  
Improve Cost

Abstract. In order to provide telecommunication and FTTH services, we, NTT, have installed a large number of facilities such as utility poles and optical cables. The number of poles is about 11.9 million and the total length of all installed cables is now about 2.3 million km. These facilities are inspected and maintained by visual inspection by workers every 5 to 10 years, which imposes great costs on the operator. Therefore, we are researching a novel outside-facility renovation technology that can improve cost-effectiveness by long-term safe use. This technology consists of two techniques: a visualization technique of unbalanced tension and a quantitative analysis technique to determine the relationship between unbalanced tension and structural deterioration. In this paper, we describe the concept of the proposed technology. When a utility pole is newly installed, its design assumes that the maximum load consists of wind pressure on the cables. However, when it is impossible to construct a guy wire for bearing the load applied to the utility pole, an unbalanced load occurs because the load cannot be balanced. In addition, when the number of users of various services increases and cables are newly laid, unbalanced loads are generated. Utility poles carrying these unbalanced loads are at significant risk of collapse due to the presence of deflection, inclination, and cracks. Our proposal focuses on the unbalanced load itself, and by detecting and countering it, we aim to enable the use of outside-facilities for a longer period than at present and to reduce replacement costs without sacrificing safety and security. In addition, we also describe how ensuring the long-term safe use of outside-facilities can improve cost-effectiveness. The proposed technique first acquires 3D point cloud data by using 3D laser scanner. It then creates a 3D facility model and calculates the tension in utility poles and cables. In addition, we introduce a novel method to estimate the loads and tension of a whole span from part of the span. Experiments are conducted to compare the estimated and measured values. The results confirm the good agreement of the values (within 10%) which validates the proposal. We aim to realize a tension visualization scheme with improved accuracy.

Development and Experimental Verification of Sliding Elements of Transparent Loggia Enclosures in High-Rise Building

2016 ◽  
Vol 861 ◽  
pp. 3-10
Author(s):  
Boris Bielek ◽  
Daniel Szabó ◽  
Dagmara Čeheľová
Keyword(s):  
Boundary Condition ◽  
Experimental Verification ◽  
Residential Building ◽  
Maximum Load ◽  
Wind Pressure ◽  
Aerodynamic Load ◽  
High Rise ◽  
Large Pressure ◽  
Final Design ◽  
Pressure Suction

Originally open balconies and loggias of high-rise residential building showed a significant aerodynamic load - discomfort for users. Subject of the contract cooperation with the investor was therefore development, experimental verification and optimization of the strength and functional parameters of sliding elements of transparent loggia enclosures from the effect of the dynamically changing wind pressure (pressure - suction), as well as the elimination of undesirable acoustic expressions. This paper introduces the aerodynamic study of the building with the objective of quantifying the maximum load on sliding elements from the effects of wind as the boundary condition for their dimensioning. It describes the final design of transparent sliding elements and their experimental verification in a large pressure chamber in laboratory. The elimination of undesirable acoustic expressions was successfully implemented through design optimization with use of acoustic camera.

scholarly journals Aerodynamic Performance and Wind-Induced Responses of Large Wind Turbine Systems with Meso-Scale Typhoon Effects

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3696
Author(s):  
Shitang Ke ◽  
Lu Xu ◽  
Tongguang Wang
Keyword(s):  
Wind Turbine ◽  
Forecast Model ◽  
Aerodynamic Performance ◽  
Wind Pressure ◽  
Induced Response ◽  
Induced Responses ◽  
Simulation Accuracy ◽  
Large Wind ◽  
Stop Position ◽  
Meso Scale

The theoretical system of existing civil engineering typhoon models is too simplified and the simulation accuracy is very low. Therefore, in this work a meso-scale weather forecast model (WRF) based on the non-static Euler equation model was introduced to simulate typhoon “Nuri” with high spatial and temporal resolution, focusing on the comparison of wind direction and wind intensity characteristics before, during and after the landing of the typhoon. Moreover, the effectiveness of the meso-scale typhoon “Nuri” simulation was verified by a comparison between the track of the typhoon center based on minimum sea level pressure and the measured track. In this paper, the aerodynamic performance of large wind turbines under typhoon loads is studied using WRF and CFD nesting technology. A 5 MW wind turbine located in a wind power plant on the southeast coast of China has been chosen as the research object. The average and fluctuating wind pressure distributions as well as airflow around the tower body and eddy distribution on blade and tower surface were compared. A dynamic and time-historical analysis of wind-induced responses under different stop positions was implemented by considering the finite element complete transient method. The influence of the stop position on the wind-induced responses and wind fluttering factor of the system were analyzed. Finally, under a typhoon process, the most unfavorable stop position of the large wind turbine was concluded. The results demonstrated that the internal force and wind fluttering factor of the tower body increased significantly under the typhoon effect. The wind-induced response of the blade closest to the tower body was affected mostly. The wind fluttering factor of this blade was increased by 35%. It was concluded from the analysis that the large wind turbine was stopped during the typhoon. The most unfavorable stop position was at the complete overlapping of the lower blade and the tower body (Condition 1). The safety redundancy reached the maximum when the upper blade overlapped with the tower body completely (Condition 5). Therefore, it is suggested that during typhoons the blade of the wind turbine be rotated to Condition 5.

DESIGN WIND PRESSURE COEFFICIENTS FOR LOW-RISE GABLE-ROOFED STEEL BUILDINGS

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Seiya Gunji ◽  
Kosuke Sato ◽  
Yasushi Uematsu
Keyword(s):  
Time History ◽  
Bending Moment ◽  
Maximum Load ◽  
Wind Pressure ◽  
Steel Buildings ◽  
Wind Force ◽  
Pressure Coefficients ◽  
History Of ◽  
Load Effects ◽  
Building Standards

The present paper discusses the wind pressure coefficients for the main wind force resisting systems of low-rise gable-roofed steel buildings, based on a wind tunnel experiment and a two-dimensional frame analysis. The wind pressure coefficients should be determined so that they reproduce the maximum load effects. Here, focus is on the bending moments involved in the members as the load effects. The Load Response Correlation (LRC) method is employed for evaluating the equivalent static wind pressure coefficients. Using the time history of wind pressure coefficients, the maximum load effects were computed for all combinations of frame location and wind direction. The results indicate that the most critical condition occurs on the windward frame in a diagonal wind. The largest bending moment was compared with that predicted from the wind pressure coefficients specified in the Japanese building standards, which are based on the area-averaged mean wind pressure coefficients. Finally, more reasonable wind pressure coefficients for designing the main wind force resisting systems are proposed.

Wind Pressure

1894 ◽  
Vol 37 (950supp) ◽  
pp. 15182-15183
Keyword(s):  
Wind Pressure

An in vitro Comparison of Two Replacement Techniques Utilizing Fascia Lata after Cranial Cruciate Ligament Transection in the Dog

1993 ◽  
Vol 06 (02) ◽  
pp. 85-92 ◽  
Author(s):  
G. L. Coetzee
Keyword(s):  
Femoral Condyle ◽  
Cruciate Ligament ◽  
Maximum Load ◽  
Fascia Lata ◽  
Patellar Ligament ◽  
Cross Sectional ◽  
Cranial Cruciate Ligament ◽  
Replacement Technique ◽  
Over The Top

SummaryThe immediate postoperative biomechanical properties of an “underand-over” cranial cruciate ligament (CCL) replacement technique consisting of fascia lata and the lateral onethird of the patellar ligament, were compared with that of a modified intra- and extracapsular “under-and-over-the-top” (UOTT) method. The right CCL in twelve adult dogs was dissected out and replaced with an autograft. The contralateral, intact CCL served as the control. In group A, the graft was secured to the lateral femoral condyle with a spiked washer and screw. In group B the intracapsular graft was secured to the lateral femoro-fabellar ligament, and the remainder to the patellar tendon. Both CCL replacement techniques exhibited a 2.0 ± 0.5 mm anterior drawer immediately after the operation. After skeletonization of the stifles, the length and cross-sectional area of the intact CCL and CCL substitutes were determined. Each bone-ligament unit was tested in linear tension to failure at a fixed distraction rate of 15 mm/s with the stifle in 120° flexion. Data was processed to obtain the corresponding material parameters (modulus, stress and strain in the linear loading region, and energy absorption to maximum load).The immediate postoperative structural and material properties of the “under-and-over” cranial cruciate ligament replacement technique with autogenous fascia lata, were compared to that of a modified intra- and extracapsular “under-and-over-the-top” (UOTT) method. The combined UOT T technique was slightly stronger (6%), but allowed 2.8 ± 0.9 mm more cranial tibial displacement at maximum linear force.

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