Publisher(s):China Academic Journals (CD Edition) Electronic Publishing House Co., Ltd.
First Published: 2021.12.24
Discipline(s): Engineering Technology
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This book comprehensively reports the wind resistance, seismic resistance or isolation, and fire resistance of high-rise buildings, steel frame structures, concrete, etc.
1. Nonlinear viscous damper deployment for wind-induced comfortability control of high-rise buildings with random parameters
Journal of Building Structures,Part 1: Structural wind resistance,Vol 39,No. 01
The deployment of nonlinear viscous dampers for wind-induced comfortability control of high-rise buildings with random structural parameters was conducted by both traditional optimized scheme (frequency-domain analysis based on stochastic equivalent linearization of the viscously damped structural system) and probability density evolution method (PDEM) -based optimized scheme (time-domain analysis based on the original viscously damped structural system) with target functions relevant to the roof acceleration. It is indicated that in case of the same total damping coefficients, the optimal deployments of nonlinear viscous dampers using the standard deviation and failure probability of the roof acceleration can both mitigate the wind-induced structural acceleration under deterministic wind excitations, which are both more economic and efficient than the uniform deployment of nonlinear viscous dampers. Moreover, the traditional optimization scheme relying upon the minimization of standard deviation of roof acceleration is a deterministic method in essence, and is limited in the promotion of structural reliability; while the PDEM-based optimized scheme relying upon the minimization of failure probability defined by roof acceleration has the advantage of obtaining probability density function, and thereby can improve the comfortability of high-rise buildings under wind actions.
2. Assessment of pedestrian wind environment of outdoor platforms of a thousand-meter-scale mega-tall building using threshold exceedance probability approach
Journal of Building Structures,Part 1: Structural wind resistance,Vol 39,No. 02
In order to assess the pedestrian wind environment of a thousand-meter-scale mega-tall building, pedestrian wind environment of the most unfavorable outdoor platform of this building was assessed using the threshold exceedance probability approach, and partitions of wind comfort and wind safety for the outdoor platform were put forward for practical applications. Firstly, the meteorological data, at 10 m height in Dalian from the year 2004 to 2014, were statistically analyzed, and the probability for wind direction and three parameters of the Weibull distribution function for wind speed under 16 wind direction sectors were acquired. Then, based on the pedestrian hourly average wind speeds and gust speeds of the most unfavorable platform obtained from the wind environment experiment and CFD simulation, the strictness for both the Lawson criterion and NEN 8100 criterion to assess the wind environment was compared in detail. Lastly, wind environment assessment of the outdoor platform was conducted using the Lawson criterion, and the influences of different windshield heights and forms on the pedestrian wind environment were analyzed. The results showed that, for wind environment assessment, the NEN 8100 criterion was stricter than the Lawson criterion. Furthermore, the pedestrian wind environment of the baseline model with 3 m high windshields was very poor, and some useful aerodynamic measures should be taken to improve its quality. The aerodynamic measures, such as variance of the windshield heights and forms, were proved to be very effective to improve the wind safety, but less effective to improve the wind comfort.
3. Experimental study on aerodynamic damping of tall buildings with 2:1 rectangular cross section under full-direction wind action
Journal of Building Structures,Part 1: Structural wind resistance,Vol 38,No. 03
Tall buildings experience aeroelastic effects under the wind action due to its low natural frequency and structural damping,and significant aerodynamic damping ratio arises. Considering the first order linear sway mode, a single degree-of-freedom aeroelastic model of tall buildings with 2:1 rectangular cross section was manufactured with a geometrical scale of 1 /600, and a series of wind tunnel tests were carried out to measure the acceleration at the building top under ten different wind speeds of each wind attack angle. Random decrement technique (RDT) was adopted to identify the aerodynamic damping ratio of the building model. The aerodynamic damping ratio in along-wind and across-wind directions obtained agreed well with that from literatures. The results showed that the acceleration responses in the strong-axis were obviously larger than those in the weak-axis for tall buildings with 2:1 rectangular cross section. The along-wind aerodynamic damping ratios in strong and weak axes were both positive. However, obvious negative aerodynamic damping ratio was observed in the direction of structural strong-axis over the non-dimensional critical wind velocity of 5.5. The feature of aerodynamic damping ratio in across-wind direction can represent that in full-direction wind.
Journal of Natural Disasters,Part 1: Structural wind resistance,Vol 26,No. 04
During the period in which Typhoon Dujuan landed, a high-rise building in Wenzhou City was employed to undergo field measurement. And the data on wind field and the acceleration response of structure were obtained. Then the modal parameters of the structure were identified to obtain the natural frequency, mode shape and damping ratio. The acceleration responses obey Gaussian distribution after their signals were denoised, and the velocity and displacement responses were acquired by integrating the acceleration response. Meanwhile, the equivalence principle, utilized in establishing the simplified five-mass point bending-shear model of the high-rise building, was engaged to demonstrate that its dynamic characteristics were similar to the original structure. The simplified mode was applied again to inverse fluctuating wind load. Then, the fluctuating wind load was superimposed to the average wind load to obtain the total wind load which was loaded on the simplified model. And after analyzing the wind-induced response with Newmark- β method, the research shows that the calculated and measured acceleration responses match well.
Earthquake Engineering and Engineering Dynamics,Part 1: Structural wind resistance,Vol 36,No. 05
In the Chinese load code, the background component factor and the resonant component factor are the main parameters for calculating the dynamic response factor. Simplified formula is used to calculate the background component factor with the fundamental mode shape in the load code adopted. In this paper, the calculation results of the simplified formula and the detailed formula were compared. Then based on different fundamental mode shapes, the results of dynamic response factors and equivalent static wind loads were compared also. Numerical example shows that using the fundamental mode shape in the code, the results by the two formulas are consistent. Compared with the results by using some other fundamental mode shapes, the dynamic response factors calculated by the fundamental mode shape in the code are different. Furthermore, the error of the base shear force may reach to more than 5%. Based on the index-type model expressions, the coefficients k and a1 of the simplified formula were fitted by the nonlinear least-squares method, with which the calculating results of the simplified formula are basically consistent to that of the detailed formula.
6. Typhoon velocity field simulation and wind-induced vibration analysis of monitored the K11 Building in Hong Kong
Journal of Building Structures,Part 1: Structural wind resistance,Vol 37,No. 06
A monitoring system with anemometers and accelerometers was deployed on the top floor of the K11 Building in Hong Kong for continuously recording the full-scale wind field and the dynamic responses of the structure. With the full-scale measurement data of wind velocity on the top floor, the typhoon velocity field around the building was numerically simulated at 16 representative floors by the weighted amplitude wave superposition method (WAWS) combined with the theoretical typhoon profiles of mean velocity and turbulence intensity. Wind-induced vibration analysis of the building was carried out both in time domain method based on the numerical wind field and in frequency domain method based on the wind tunnel test. The results show that the acceleration responses in terms of the extreme values, standard deviations and power spectrum density functions, obtained by the time domain method are more close to the full-scale measurement response results compared with those obtained by the frequency domain method.
7. Effects of different setback measures on across wind effects of super-tall buildings under strong typhoon
Journal of Building Structures,Part 1: Structural wind resistance,Vol 37,No. 07
Thewind pressures on several setback and rotating setback building models were measured and recorded synchronously under simulated boundary layers representing typhoon wind field through the synchronous multi-pressure scanning system in wind tunnel. The effects of different setback on across-wind aerodynamic forces, power spectrum density for aerodynamic bending moment, and characteristics of wind-induced response were analyzed. Results show that for buildings with uniform square cross-section, the vortex shedding is at the same constant frequency along height. However, for setback buildings, the vortex shedding is at different frequency along height. That is effective for reducing the across-wind aerodynamic forces and wind-induced responses. Rotating setback suppresses vortex shedding and leads to further reductions in across-wind aerodynamic forces and wind-induced responses. The aerodynamic bending moment M A is affected mainly by the distribution of mode-weighting aerodynamic force F m. For the square-section model, the most influential F m occurs at 80% of the building height. For the setback models, the aerodynamic loads that mainly contribute to M A still occur at the top of the building and the most influential height locates at the range of 80%–90% of the building height. Compared with the square-section model, different setback measures can reduce across-wind load by 75%–79.2%. The rotating setback measure can reduce across-wind load by 91%.
Earthquake Engineering and Engineering Dynamics,Part 1: Structural wind resistance,Vol 35,No. 08
Wind pressure characteristics of high-rise building with different interference buildings are investigated bases on the pressure tests with rigid model. The results indicate that: (1) For single building configuration, the mean wind pressure coefficients on the windward wall are positive, while those on the side faces and the back face are all negative, and the mean wind pressure coefficients for measuring points located on the middle and upper parts of the windward face are larger than those located on lower parts. (2) Negative wind pressures appear on the windward face because of the shielding effect by the interference buildings located on upwind direction. (3) Due to the interference of the surrounding buildings, the fluctuating wind pressure coefficients are larger than those for single building case. (4) The interference effects for case of surrounding buildings in upwind direction are more evident than that in downwind direction. The outcomes of this study are expected to be useful to determine the wind loads on the tall building in the design stage, and also provide guidelines for the design and wind tunnel tests for other similar structures in the future.
9. A probabilistic method for estimating extreme wind pressure on structures considering direction effect of extreme wind speed
Journal of Building Structures,Part 1: Structural wind resistance,Vol 39,No. 09
The design wind load on building envelop, which represents the extreme wind pressure in a given return period, is generally estimated by the most unfavorable method in engineering application, which is not precise in the sense of probability. The relatively precise design wind loads can only be obtained when the characteristic of both the extreme values of wind speed and wind pressure coefficient, such as their randomness, directionality and correlation, were taken into consideration. In view of this problem, a probabilistic method for estimating the design wind load on building envelope was proposed in this paper which had an overall consideration of the randomness and direction effect of the extreme wind speed and wind pressure coefficient. The three main factors for estimating the extreme wind pressure, which were the distributions of directional extreme wind speed, the Cook-Mayne wind pressure coefficient and the information of the correlation among extreme wind speeds in different wind directions, were induced from the existing samples. Then, a formula for estimating extreme wind pressure was proposed based on the three main factors. The accuracy and practicability of the proposed method was verified by an example of a high-rise building in Shanghai, in which the results were compared to the most unfavorable values widely used in engineering work.
Journal of Building Structures,Part 1: Structural wind resistance,Vol 37,No. 10
In order to find a reasonable estimation method of design wind loads inside a building envelope, wind tunnel tests were carried out on a typical building with four different opening cases. Distributions of peak factors and peak internal pressures on internal surfaces of building roof and longitudinal wall were studied and compared with corresponding results calculated with the current code (GB 50009–2012) method. Based on that, an alternative method for estimating peak internal pressures along with values of associated design parameters was presented. The study shows that the code method would provide varying peak internal pressures along the building height, while the wind tunnel experiment indicates that the peak wind pressures are actually uniformly distributed inside the building. The current load code may underestimate the value of peak factor without regard to non-Gaussian characteristics of wind loads. For the sealed case of the building, using the code method may result in a larger peak internal pressure than the experimental one due to overestimation of internal pressure fluctuations. However, for the building with a dominant opening, the code would underestimate peak internal pressures on the low levels of longitudinal walls even if raising the peak factor to 3.5.
11. Comparison of probability distribution models of non-Gaussian peak factor of wind pressure on cladding and components
Journal of Building Structures,Part 1: Structural wind resistance,Vol 37,No. 11
The characteristics of probability distribution formulas determined by classic extreme value model and non-Gaussian peak factor method were investigated respectively based on the non-Gaussian pressure results of roofs and walls on saddle-roofed structures. Results show that for the components and cladding, the probability distribution of peak factor can be estimated by Gumbel distribution (type I) appropriately, which is significantly consistent with that obtained by the generalized extreme distribution. Moreover, especially for the common fractiles of 57% and 78% in practice, previously mentioned comparison errors are minimal. The analytical expression of non-Gaussian peak factor is formulated by coefficients of skewness, kurtosis and Gaussian peak factor from time history samples, including features of parent probability distribution. Compared with classical extreme distribution method, this non-Gaussian peak factor model is capable of dealing with any strong and weak Gaussian cases, due to utilizing more comprehensive sample information. Fractile of non-Gaussian peak factor method is moderately larger than that computed by classical extreme theory with the same occurrence probability of extreme value, which consequently can evaluate large fractile probability distribution suitably.
Journal of Building Structures,Part 1: Structural wind resistance,Vol 40,No. 12
The present research proposed a simplified engineering model of wind pressure spectra that can describe the characteristics of body-induced turbulence around long-span roofs. The model was based on the spectral analyses of the 18 048 samples of wind tunnel data of 1 730 working conditions on five types of typical long-span roofs including flat, cantilevered, cylindrical, spherical, and saddle roofs. Two key parameters, namely, the peak frequency and the coherence index were introduced to describe the wind pressure spectra and to develop the simplified model. As a result, the mentioned five types of long-span roofs can be divided into three categories from spectral perspective. Category Ⅰ is bluff body with sharp corners represented by flat and saddle roofs. Category Ⅱ is cantilevered roof featuring planar flow. Category Ⅲ is curved bluff body represented by cylindrical and spherical roofs. For Categories Ⅰ and Ⅱ, the peak frequencies are concentrated on 0.1–0.2 Hz, while the coherence indexes are concentrated on 2.5 and 3.5, respectively. For Category Ⅲ, the peak frequencies are below 0.1 Hz, and the mode of coherence index is 4.0. Finally, through statistical analyses, the zone values of spectral parameters are given for engineering reference.
13. Investigation on wind load and wind-induced response of the large-span retractable roof based on experiment and numerical calculation
Earthquake Engineering and Engineering Dynamics,Part 1: Structural wind resistance,Vol 39,No. 13
To study the effect of roof opening on the wind effect of the large-span roof structure, we carried out wind tunnel tests on a large-span retractable roof in a boundary layer wind tunnel. Then the characteristics of wind loads on the roof were studied, and the wind-induced responses influenced by the opening were investigated in the time-domain. The results show that the models for the large-span structure were concentrated; the largest modal energy occurred in the first model; the contributions from high order were not ignored. The wind loads reduced with the roof opening; the same tendency was found for the wind vibration coefficient as well as the displacement response and acceleration response. The output will be a reference for the load design of the large-span retractable roof.
14. Research on effects of geometric characteristics on critical Reynolds number ranges of cylindrical roofs in wind tunnel
Journal of Building Structures,Part 1: Structural wind resistance,Vol 37,No. 14
There is a strong dependence of aerodynamic loads for large-span cylindrical roofs on Reynolds number effect, and the Reynolds number sensitivities are greatly influenced by the geometric characteristics of the roofs. As a result, based on the series of Reynolds number tests of cylindrical roof model, the influences of geometric parameters on the Reynolds number effects were investigated. Different rise-span ratios ( f/ L was from 1/6 to 1/2) and width-span ratios ( B/L was from 1 to 12) were considered, and the Reynolds numbers ranged from 6.90×10 4 to 1.38×10 6. Based on the data derived from wind tunnel tests, the wind pressure distributions, pressure gradients and lift and drag force coefficients were analyzed. The test results show that there is a direct shift of the transitional Reynolds number towards high Re level owing to the increasing rise-span ratio, whilst the decreasing width-span ratio. This reveals that three-dimensional flow will postpone the transition of separated shear layers from laminar to turbulent over the roof surface. The lower limits of critical Reynolds number increases from 1.66×10 5 to 4.14×10 5 with B/L decreasing from 12 to 1, whilst the lower limits increases from 2.48×10 5 to 4.14×10 5 with f/L increasing from 1/3 to 1/2. There is no Reynolds number effect for cylindrical roofs with f/L of 1/6 in the range of test Reynolds number from 6.9×10 4 to 2.48×10 5.
15. Research on similarity criterion of wind-induced snowdrift experiments based on wind-snow combined experiment facility
Journal of Building Structures,Part 1: Structural wind resistance,Vol 40,No. 15
Wind-induced snowdrift phenomenon leads to the unbalanced distribution of snow on the building roofs, which could bring a huge safety hazard to the structure. The wind tunnel test is one of the main methods to study wind-induced snowdrift, and similarity theories are the basis of wind tunnel test. In this paper, the similarity theories of Kind, Iversen, and Tabler were firstly summarized. After the classification, the main similarity criteria were then summarized, including Froude, Reynold, time similarity criterion, and speed similarity criterion. Making use of the wind-snow combined experiment facility, taking artificial snow as the simulating granular material, as well as considering characteristics of different similarity criteria sufficiently, Oikawa conducted the scale experiments on snow distribution around a 0.5 m cube according to the selected similarity criterion, with the field observation on snow distribution around a 1 m cube as the prototypes. Finally, according to the comparison of the prototypes and scale experiments, and with a full consideration of the characteristics of each similarity criterion, the similarity criterion based on the mass transfer rate of saltation process is proved to be the most reliable for the reappearance of snow distribution, and the experimental results are in good agreement with the prototype when the mean wind speed of the prototype is used.
16. State of the progress and prospect of research on wind-sand flow and wind-sand load of buildings
Journal of Natural Disasters,Part 1: Structural wind resistance,Vol 25,No. 16
Buildings are attacked seriously by wind-sand flow in western and northern China, whose effects of actions are greater than that of wind loads. As it is lesser that study on wind-sand resistance design theory and design method of buildings in our country, the research on wind-sand flow and wind-sand load of buildings has important theoretical and engineering significance. This paper briefly reviews the study history of wind-sand flow, and summarizes the research progress of physical parameters models, such as the distribution of sediment transport capacity along height, models of sand transport rate, critical sand-raising wind velocity, wind profile, wind-sand two phase flow models and wind-sand loads of buildings at home and abroad. Then, it summarizes the current problems existing in the research on wind-sand two phase flow and wind-sand loads of buildings. Finally, this paper proposes the development prospect of integrated application of wind-sand field measurement, wind tunnel test and numerical simulation method for the research on building wind-sand load and wind-sand flow.
17. Investigation on interference effects on peak wind loads on a group of buildings with flat roof under different arrangements
Journal of Building Structures,Part 1: Structural wind resistance,Vol 39,No. 17
Fluctuating wind pressures on a group of low-rise buildings with flat roofs were measured by wind tunnel test. And the influences of building row, column and building area density on the interference effects of peak wind pressure on the roof zone of the buildings located at the corner, edge and center of the building group were investigated by a single factor rotation method. The results demonstrate that the shielding effects on peak wind loads of most roof zones are noticeable. The shielding effects are particularly significant for the entire roof zones of the center buildings and for the corner and central roof zones of the corner and edge buildings. In addition, amplification effects occur at the edge middle roof zones, where the largest increase reaches 14%. Increasing the building row or column has more significant effects on corner and edge building, where the shielding effects of the corner and center roof zones are further amplified. For the building group with three rows and three columns, the interference factors of all the roof zones of the center building, and those of the corner roof zones (near the building group center) of the corner and edge buildings, are more sensitive to the building area density, and the values decrease linearly (proportional coefficient is close to ?1.0) with an increase in the building area density. In contrast, the interference factors of the corner roof zones away from the building group center for the corner and edge buildings are less sensitive to the building area density.
Journal of Building Structures,Part 1: Structural wind resistance,Vol 37,No. 18
Integral steel platform system (ISPS) is one kind of construction equipment which is developed to construct core tube of high-rise buildings. An aeroelastic model of ISPS and a rigid model of core tube were designed, manufactured and assembled together in accordance with the actural engineering situation in order to research windinduced vibration. Wind tunnel experiments were carried out to measure the displacements and accelerations of ISPS under different wind speeds, wind angles for two work conditions, namely after-lifting condition and before-lifting condition. The test results show that obvious torsion vibration appears in turbulence flow field. The most unfavorable wind angle is the wind angle of 0°. Response values in along wind direction are greater than those in across wind direction. Displacements and accelerations in CONDITION A are greater than those in CONDITION B; Displacements in turbulence flow field are greater than those in uniform flow field, and the impact of fluctuating wind on the structure cannot be ignored. The most adverse case is CONDITION A with 0° wind angle, thus this case should be regarded as the design condition of ISPS. If only the ISPS is taken as the analysis object while do not consider the core tube, calculation and analysis of the ISPS can be greatly simplified and more secure.