Elastic-plastic study on high building with SRC transferring story

A new type of transferring structure for steel reinforced concrete (SRC) beams is used in high building. The pushover analysis method was used to study the failure mechanism and ductility of SRC transferring structure through consulting pseudo-static test results for the structure. And, the occurrence order and position of the plastic hinge, the weak story and seismic capacity of high building with SRC transferring story were also studied through consulting shaking table test results for the high building, showing that the seismic behavior of high building with SRC transferring story is good.

The Numerical Simulation of Recoil Caused by Blasting Demolition of High Buildings

On the basis of recoil in the process of blasting demolition of high buildings, this thesis applies dynamics theory to predict whether the phenomena of recoil will occur or not by simulation and calculation of the recoil and the pressure suffered from the rudimental supporter in the process of demolition. The criterion of recoil relies on whether recoil can be overcome by the intensity of reservation or friction. To take the obliquity as increment, and to calculate the recoil and the pressure suffered from the rudimental supporter in correspondence with the every obliquity in the demolition by VC program, the relation curve can be obtained between recoil and obliquity. By means of examples testified with programs, the obtained results are consistent with those of practice.

Studies on wind environment around high buildings in urban areas

High buildings or architectural complex in urban areas remarkably distort the urban surface wind fields. As the air flow approaches,local strong wind may appear around the buildings. The strong wind makes the pedestrians on sidewalks, entrances and terrace very uncomfortable and causes the pedestrian level wind environment problem. In this studies, hot-wire wind measurement, wind scouring in wind tunnel and numerical computation were carried out to evaluate the wind environment of tall buildings in the prevailing flow conditions in Beijing areas. The results obtained by three techniques were compared and mutually verified. The conclusions drawn from three approaches agree with each other. Also the advantages and limitations of each method were analyzed. It is suggested that the combination of different techniques may produce better assessment of wind environment around high buildings.

Quantitative investigation on collapse margin of steel high-rise buildings subjected to extremely severe earthquakes

Reponses of structures subjected to severe earthquakes sometimes significantly surpass what was considered in the design.It is important to investigate the failure mechanism and collapse margin of structures beyond design,especially for high-rise buildings.In this study,steel high-rise buildings using either square concrete-filled-tube（CFT） columns or steel tube columns are designed.A detailed three-dimensional（3 D） structural model is developed to analyze the seismic behavior of a steel high-rise towards a complete collapse.The effectiveness is verified by both component tests and a full-scale shaking table test.The collapse margin,which is defined as the ratio of PGA between the collapse level to the design major earthquake level（Level 2）,is quantified by a series of numerical simulations using incremental dynamic analyses（IDA）.The baseline building using CFT columns collapsed with a weak first story mechanism and presented a collapse margin ranging from 10 to 20.The significant variation in the collapse margin was caused by the different characteristics of the input ground motions.The building using equivalent steel columns collapsed earlier due to the significant shortening of the locally buckled columns,exhibiting only 57% of the collapse margin of the baseline building.The influence of reducing the height of the first story was quite significant.The shortened first story not only enlarged the collapse margin by 20%,but also changed the collapse mode.

Optimization of Grouping Evacuation Strategy in High-rise Building Fires Based on Graph Theory and Computational Experiments

It is difficult to rescue people from outside, and emergency evacuation is still a main measure to decrease casualties in high-rise building fires. To improve evacuation efficiency, a valid and easily manipulated grouping evacuation strategy is proposed. Occupants escape in groups according to the shortest evacuation route is determined by graph theory. In order to evaluate and find the optimal grouping, computational experiments are performed to design and simulate the evacuation processes. A case study shown the application in detail and quantitative research conclusions is obtained. The thoughts and approaches of this study can be used to guide actual high-rise building evacuation processes in future.

Dynamic response characteristics of super high-rise buildings subjected to long-period ground motions

Spectrum characteristics of different types of seismic waves and dynamic response characteristics of super high-rise building structures under long-period ground motions were comparatively analyzed. First, the ground response wave (named LS-R wave) of a soft soil site with deep deposit, taking long-period bedrock seismic record as input, was calculated by wave propagation method. After that, a TOMAKOMAI station long-period seismic record from the Tokachi-Oki earthquake and conventional El-Centro wave were also chosen. Spectrum characteristics of these waves were analyzed and compared. Then, a series of shaking table tests were performed on a 1:50 scale super high-rise structural model under these seismic waves. Furthermore, numerical simulation of the prototype structure under these excitations was conducted, and structure damages under different intensive ground motions were discussed. The results show that: 1) Spectrum characteristics of ground response wave are significantly influenced by soft soil site with deep deposit, and the predominant period has an increasing trend. 2) The maximum acceleration amplification factor of the structure under the TOM wave is two times that under the El-Centro wave; while the maximum displacement response of the structure under the TOM wave is 4.4 times that under the El-Centro wave. Long-period ground motions show greater influences on displacement responses than acceleration responses for super high-rise building structures. 3) Most inelastic damage occurs at the upper 1/3 part of the super high-rise building when subjected to long-period ground motions.

Safety analysis of optimal outriggers location in high-rise building structures

This paper presents the restraining moments of outriggers acting on the core wall and the equation of the horizontal top deflection based on a simplified outrigger model. The deformation compatibility conditions between outriggers and core wall as well as the finite rigidities of outriggers are also considered. One case study was carried out to analyze the horizontal top deflection and the mutation of the restraining moments caused by the variation of outrigger location. The results showed that the method adopted in the paper is simple and reasonable. Some conclusions are valuable to the safety design of high-rise building structures.

A review on research of fire dynamics in high-rise buildings

Since serious fire occurred frequently in recent years, fire safety of high-rise building has attracted extensive attention. A National Basic Research Program （973 program） of China has been set up by Ministry of Science and Technology （MOST） of China in 2012 to meet the research requirements of fire safety in high-rise buildings. This paper reviews the current state of art of research on fire dynamics of high-rise buildings, including the up-to-date progress of this project. The following three subjects on fire dynamics of high-rise buildings are addressed in this review： the ejected flame and fire plume behavior over facade out of the compartment window, the flame spread behavior over facade thermal insulation materiMs, and the buoyancy-driven smoke transportation characteristics along long vertical channels in high-rise buildings. Prospective future works are discussed and summarized.

Effects of high modes on the wind-induced response of super high-rise buildings

For super high-rise buildings, the vibration period of the basic mode is several seconds, and it is very close to the period of the fluctuating wind. The damping of super high-rise buildings is low, so super high-rise buildings are very sensitive to fluctuating wind. The wind load is one of the key loads in the design of super high-rise buildings. It is known that only the basic mode is needed in the wind-response analysis of tall buildings. However, for super high-rise buildings, especially for the acceleration response, because of the frequency amplification of the high modes, the high modes and the mode coupling may need to be considered. Three typical super high-rise projects with the SMPSS in wind tunnel tests and the random vibration theory method were used to analyze the effect of high modes on the wind-induced response. The conclusions can be drawn as follows. First, for the displacement response, the basic mode is dominant, and the high modes can be neglected. Second, for the acceleration response, the high modes and the mode coupling should be considered. Lastly, the strain energy of modes can only give the vibration energy distribution of the high-rise building, and it cannot describe the local wind-induced vibration of high-rise buildings, especially for the top acceleration response.

Numerical Simulation of Wind Field Characteristics around Two Adjacent High-Rise Buildings

This paper based on Reynolds-averaged Navier-Stokes equations standard ?model [1];the surface pressure on the wind field around two adjacent high-rise buildings was numerically simulated with software Fluent. The results show that with the influence of adjacent high-rise building, numerical simulation is a good way to study the wind field around high-rise building and the distribution of wind pressure on building’ surface. The pressures on the windward surface are positive with the maximum at 2/3 H height and have lower values on the top and bottom. The pressures on the leeward surface and two sides were negative. Due to the serious flow separation at the corner of building’s windward, the wind field has a high turbulent kinetic energy.

Wind tunnel test and numerical simulation of wind pressure on a high-rise building

We carried out a wind tunnel test to measure cladding loads for a high-rise building of 295 m in height,which would be located in the business center of Chongqing Municipality,P.R.China.The rigid model was used to determine fluctuating local pressures on the exterior surfaces of the building.The wind tunnel test results show the critical zone of wind pressures on building surfaces in both standalone and interference conditions.The computational fluid dynamics(CFD)was conducted by using the FLUENT Code to compare with the wind tunnel test results,and the steady three-dimensional turbulent flow with Realizable k-ε as a turbulence model was used.The CFD results are agree with the wind tunnel test results in regards to distributions of wind pressures over a high-rise building's surfaces.

Multi-hazard performance assessment of a transfer-plate high-rise building

Many urban areas are located in regions of moderate seismicity and are subjected to strong wind. Buildings in these regions are often designed without seismic provisions. As a result, in the event of an earthquake, the potential for damage and loss of lives may not be known. In this paper, the performance of a typical high-rise building with a thick transfer plate （TP）, which is one type of building structure commonly found in Hong Kong, is assessed against both earthquake and wind hazards. Seismic- and wind-resistant performance objectives are first reviewed based on relevant codes and design guidelines for high-rise buildings. After a brief introduction of wind-resistant design of the building, various methodologies, including equivalent static load analysis （ESLA）, response spectrum analysis （RSA）, pushover analysis （POA）, linear and nonlinear time-history analysis （LTHA and NTHA）, are employed to assess the seismic performance of the building when subjected to frequent earthquakes, design based earthquakes and maximum credible earthquakes. The effects of design wind and seismic action with a common 50-year return period are also compared. The results indicate that most performance objectives can be satisfied by the building, but there are some objectives, such as inter-story drift ratio, that cannot be achieved when subjected to the frequent earthquakes. It is concluded that in addition to wind, seismic action may need to be explicitly considered in the design of buildings in regions of moderate seismicity.

The Building Extraction Based on Object Oriented Classification Method in High Vegetation Coverage Area

Quickly extraction of building information technology is an important application in urban development planning, electronic information, national defense and others. This paper takes Landsat-8 multispectral and panchromatic data as data source, using the local variance method to select the optimal segmentation scale, normalized difference vegetation index (NDVI) and the normalized building index (NDBI) and panchromatic brightness value of an object oriented classification rule extraction. The high vegetation coverage area of buildings, and through the spatial relationships and distinguishing feature of collections of buildings independent buildings and villages. The results showed that Google earth high resolution image analysis and accuracy evaluation. the results of the extraction based on the overall accuracy of village extraction was 83%, the accuracy of extraction of independent buildings was 70%, according to the L8 remote sensing data, object oriented classification method can quickly and accurately extract the high vegetation coverage area of the building.

High-rise building fire pre-warning model based on the support vector regression

Aiming at reducing the deficiency of the traditional fire pre-warning algorithms and the intelligent fire pre-warning algorithms such as artificial neural network,and then to improve the accuracy of fire prewarning for high-rise buildings,a composite fire pre-warning controller is designed according to the characteristic（ nonlinear,less historical data,many influence factors）,also a high-rise building fire pre-warning model is set up based on the support vector regression（ SV R）. Then the wood fire standard history data is applied to make empirical analysis. The research results can provide a reliable decision support framework for high-rise building fire pre-warning.

Simulation on spread of fire smoke in the elevator shaft for a high-rise building

Spread of fire smoke in the elevator shaft of a high-rise building is influ- enced by many driving facts. We simulate smoke spreading in the elevator shaft, stair room, and pre-chamber with and without different supplied pressurized air. The simulation shows that smoke moves very fast in the elevator shaft. When a 12 floor high-rise building is in fire, smoke can fill up the elevator shaft in less than 1.5 min after a fire started, temperature in the elevator shaft can be higher than 187℃ in 5 rain, and the concentration of CO can also reach a high level. The elevator shaft has a very low visibility in less than about 100 s.

Field measurements for calibration of simplified models of the stiffening effect of infill masonry walls in high-rise RC framed and shear-wall buildings

As a type of nonstructural component, infill walls play a significant role in the seismic behavior of high-rise buildings. However, the stiffness of the infill wall is generally either ignored or considered by simplified empirical criteria that lead to a period shortening. The difference can be greatly decreased by using a structural identification methodology. In this study, an ambient vibration test was performed on four on-site reinforced concrete high-rise buildings, and the design results were compared with the PKPM models using corresponding finite element(FE) models. A diagonal strut model was used to simulate the behavior of the infill wall, and the identified modal parameters measured from the on-site test were employed to calibrate the parameters of the diagonal strut in the FE models. The SAP2000 models with calibrated elastic modulus were used to evaluate the seismic response in the elastic state. Based on the load-displacement relationship of the infill wall, nonlinear dynamic analysis models were built in PERFORM-3 D and calibrated using the measured modal periods. The analysis results revealed that the structural performance under small/large earthquake records were both strengthened by infill walls, and the contribution of infill walls should be considered for better accuracy in the design process.

Development of the Separate Air-Supply Type of Pressurization Smoke Control System for the Stairwells of High-Rise Buildings in Korea

The pressurization smoke control system has been commonly used as a smoke control system at the emergency stairs of high-rise buildings. However, a higher possibility of overpressure between the lobby and the accommodation or pressure drop in the lobby could lead to failure in achievement of the purpose of pressurization system, particularly when supplying the leakage and supplementary air flow through one air-supply path at a time. To improve this particular issue, the devise configurations, as well as the different ways to supply the leakage and supplementary air flow through the different flow passages have been proposed. The performance of the trial product was evaluated on the test bed, ultimately providing a safe evacuation environment if high-rise buildings fired.