Demands Of High-rise Buildings Research Articles

Comparison of Seismic Performance of Buildings with Conventional Slab and Flat Slab in Different Zones of Bangladesh

As usable land is scarce in Bangladesh, the demand for high-rise buildings has risen over the past few decades. Conventionally, reinforced cement concrete (RCC) structures in Bangladesh have been used for residential, educational, institutional & commercial purposes. Bangladesh is located in a relatively earthquake-prone region on the fault plane; it is of utmost importance to assess seismic conditions while constructing a structure. Three types of slabs have been analyzed: conventional RCC slab, flat slab with drop panel, and flat slab with drop panel & shear wall. Typically, a conventional RCC slab contains a beam, column & slab with a large thickness of the beam. To avoid this, a flat slab with a drop panel may be used, but it has some limitations. As it has no lateral support, a flat slab with a shear wall can be replaced to gain more stability. According to BNBC 2006, Bangladesh was divided into three seismic zones. However, according to BNBC 2020, it is revised into four seismic zones. Seismic comparisons of three models in four seismic zones have been conducted. Maximum story displacement, maximum story drift, overturning moment and story shear have been found after analyzing three different types of models located in different seismic zones. The maximum story displacement and maximum story drift for flat slabs are greater than conventional slabs and flat slabs with shear walls. Moreover, the displacement between conventional and flat slabs with shear walls varies a little. Maximum overturning moment and story shear: it appears that for the traditional slab, the value is maximum, the flat slab is minimum, and the flat slab with the shear wall is between those two. The model for flat slab has been found to be more flexible than conventional RCC slab and flat slab with the shear wall.

High-Speed Tracking Controller for Stable Power Control in Discontinuous Charging Systems

The global population is rapidly increasing, and the urban population is on an even faster trend; therefore, the population density is expected to rise. As the number of people in cities grows, the demand for high-rise buildings is anticipated to increase to address the problem of limited land resources. Therefore, efficient energy management using distributed resources has become increasingly important. Elevators are a vital vertical means of transportation in high-rise buildings, and reducing the weight of their components can lead to favorable conditions for energy utilization and increased speed. Therefore, this study presents an elevator system that supplies power inside an elevator car by eliminating the traveling cable and applying a small-capacity energy storage system (ESS). Additionally, we propose a charging algorithm suitable for the proposed system. Generally, batteries have sensitive electrical properties among the distributed energy resources (DERs). Therefore, controlling the stable maintenance of the transient state of the charging current—even when the DC power is unstable or the load changes rapidly in a system requiring fast charging—is crucial. Owing to the nature of the elevator system to be applied, discontinuous charging is frequent, and the active and efficient management of the battery state of charge (SOC) may be challenging. In addition, since it is necessary to be able to charge as much as possible during a short discontinuous charging time, a current control algorithm with a stable and high-speed response is required. The proposed transient high-speed tracking controller (THSTC) is a method for tracking the time of applying an inductor’s excitation voltage without pulse–width modulation (PWM) switching, which is less sensitive to the controller gain values and has fast responsiveness as well as stable transient response characteristics. The proposed method has good dynamic characteristics with a simple control structure without a complex design, which is useful for systems with repeated discontinuous charging. We validate the performance and effectiveness of the proposed controller through simulations and experiments.

A seismic behavior of RCC high rise structure with and without outrigger and belt truss system for different earthquake zones and type of soil

In the present era, there is more demand for high-rise buildings. The growing de- mand for high-rise buildings brings new difficulties and comes up with new safety precautions. With an increase in height of the structure, its rigidity reduces, making it difficult to withstand earthquake and wind effects, hence some preventative structural systems must be used. Some of them are bracings, shear walls, outrig- ger systems and belt truss systems etc. The outrigger and belt truss system is investigated in this study since it is the most effective method for high-rise buildings and skyscrapers. To prevent story drift and the rotational action of the core caused by seismic and wind forces, the external columns in an outrigger system are attached to the main inner or outer core using outrigger beams, walls, and trusses etc. at various floor levels. All external columns that are situated at the peripheral are connected together with truss elements in a belt truss system. This study investigates the comparison of the behavior of high-rise buildings with and without an outrigger system, and belt truss system for all seismic zones (zone II, III, IV and V) with different types of soil (hard, medium, soft). This study is carried out for 40 story buildings using response spectrum analysis. Analysis of the building is carried out by using ETABS 2018 software. The results are in the form of seismic responses like storey displacement, Storey drift, base shear are studied. Results show that the provision of an outrigger and belt truss system reduces the story displacement of the structure. After analysis and comparing the seismic responses of the structure, the building provided with the combination of outrigger and belt truss system perform better as compared to the only outrigger and belt truss system.

The Effects of Orientation and Width of Space Between Buildings on Ventilation of High-Rise Areas

Excessive heat in the high-rise urban fabric has contributed to pedestrian and occupants' discomfort. Establishing wind circulation in space with an environmentally compatible and optimal configuration is necessary to improve comfort in this region. The study benefits from field measurements and experimental validation of CFD simulation to investigate the effective parameters that affect wind speed. The master plan has proposed decentralized and limited high-rise construction to prevent the horizontal growth of Babolsar city. Meanwhile, the demand for high-rise buildings is high in the city. Therefore, altitude density (height factor) is considered as a constant factor. The buildings' orientation and enclosure based on the passages' width have opposite reactions in the direction of the prevailing wind. The correlation between the orientation and the enclosure with the wind speed are the values of 0.504 and 0.2226 respectively, which have the highest correlation among other parameters. The changes have been made in the building orientation factor in the dominant wind direction by creating permeability as well as creating low enclosure in the paths and empty spaces perpendicular to the dominant wind (W’= 3W, E’ = 0.33E). These strategies have finally improved wind velocity and created wind circulation in urban block spaces. Finally, according to the data analysis for Climate compatible in humid areas and the optimal behavior of wind flow for proper urban ventilation, an improved layout for future developments will be presented.

Evaluation of aerodynamic effects on a tall building with various cross-section shapes having equal area

When wind hits a high-rise building, it has a big impact. Due to a lack of available land and an increase in population, the demand for high-rise buildings is growing daily. This necessitates the design of high-rise buildings with an effective wind load. Utilizing pressure and force coefficients, wind loads are calculated. There are numerous international standards that provide the coefficients for common regular shapes. However, in an expanding and competitive world, the architect seeks out complicated and unique building shapes that are aesthetically pleasing and able to endure wind loads that are applied to buildings. Our research focuses on determining how wind affects high-rise structures of seven different regular shapes that have the same base area and height. The ANSYS CFX for Computation Fluid Dynamics studies is used to compute the wind pressure on each face of building models. Scaled at 1:350, each building is represented as a model. For each face, the mean pressure coefficient CP is determined. Additionally, the wind flow pattern is also established using ANSYS CFX. Due to the direct head-on impact, pressure contours indicated positive pressure on the front or windward face. Faces turned sideways and backward displayed suction or negative pressure. On the reverse face, vortices were seen. According to the vertical flow pattern, the wind was blowing in two different directions: upward to a height of one-third of the building model from the top and downward to a height of two-thirds of the building model from the bottom.

Experimental Modelling of Helical Piles under Axial Loading


 Due to the rapid increase in population, the demand for high-rise buildings is also increasing daily. Researchers have performed various numerical and experimental studies to find out the best foundation type for structure. A helical foundation is one of the most suitable foundation types to be incorporated in the construction of high-rise buildings. In a helical pile, some fraction of axial load is taken by the helix, which increases the load-carrying capacity of the foundation. This study is carried out to determine the settlement and load carrying capacity of the helical pile and helical pile raft cohesion-less soil. For this study, a small-scale model of a helical pile and helical pile raft foundation is prepared and fitted in the rectangular shear box filled with cohesion-less soil (sand). Testing on single helix piles, double helix piles, two helical pile rafts, and four helical pile rafts has been conducted. Instrumentation of the model is carried out using a settlement transducer and load cell to note down the settlement and load applied, respectively. Results provided that the maximum axial load carrying capacity of a single helix pile is almost 1200N at a settlement of 25mm while that is 1750N, corresponding to a 25mm settlement for a double helix pile. Similarly, the maximum load carrying capacity for two helical pile rafts and four helical pile raft are 2700N and 4400N, respectively, at 25mm. These results were compared, and a double helix pile has a greater load-carrying capacity than a single helix pile. Similarly, a pile raft with four helical piles has a greater load-carrying capacity than a pile raft consisting of two helical piles.

Causes, effects and potential measures of cost deviations in high-rise building projects in Egypt

Cost deviation is a global issue that has negative impacts on projects, stakeholders and the industry. Egypt, a developing nation with the rising demand for high-rise buildings is also plagued with the issue. It is inevitable that high-rise buildings cost more than low-rise buildings, further accentuating the needs to study cost deviation from all angles, which was previously absent. Therefore, this study aims to provide an overall perspective (causes, effects and measures) of cost deviation in high-rise building projects in Egypt by adopting both quantitative (questionnaire survey) and qualitative (brain storming sessions) approaches. The questionnaire survey has been administered among various construction practitioners (project manager, consultant, quantity surveyor, site engineer) with experiences in high-rise building projects, while the brainstorming session involved expert panels from the industry. Findings from the 106 questionnaires have revealed inflation as the major cause of cost deviation that has the most effect on profit loss for the contractor. Government and project-based measures with great collaboration has been proposed to address the issue. The overall perspective (causes, effects, measures) provided in this study would be of interest to the local construction stakeholders, as well as foreign investors towards improving the cost performance of high-rise building projects in Egypt.

Importance of ‘DAF’ in evaluating structural adequacy of gravity-load designed RC buildings

The existing RC buildings in urban habitat comprises of buildings mostly constructed either before evolution of seismic provisions or has been designed only for resisting gravity loads. These buildings are found to be vulnerable for any accidental damages to any of the critical load-bearing member in the form of progressive collapse. Hence, accurate estimation of structural adequacy is imminent in transforming the existing vulnerable building stock into a sustainable building environment. Progressive collapse of structural systems is often resulted from the failure of critical structural members and change of load transfer path. The progressive collapse potential can be accurately estimated using nonlinear dynamic analysis. However, in engineering practice, a simplified linear static analysis (LSA) is often carried out with a dynamic amplification factor (DAF) to approximate the dynamic forces. In this study, the correctness of estimation of dynamic demand during progressive collapse mechanism is investigated using DAF for structural models comprising of G + 3 story, G + 10 story and G + 12 story hypothetical RC building models. The structural models are designed as per IS 456: 2000, and progressive collapse mechanism is initiated by identification and removal of load bearing critical column member leading to global failure of the structure. Nonlinear static and nonlinear dynamic analysis (NLD) is carried out using SAP2000. Structural adequacy is ascertained by computing the demand-capacity ratios (DCR) of the requisite structural members identified to be inadequate during nonlinear analysis. It has been observed from the results that DAF is inconsistent in estimating the dynamic demand for high rise buildings. The outcome of the analysis is checked with the structural behavior of existing building structure (located in Warangal city, Telangana state, India) presented in case study and can be concluded that nonlinear dynamic analysis appears to be the only alternative for analyzing the structural behavior of important high-rise buildings.

Evaluation of Simplified Analysis Procedures for a High-Rise Reinforced Concrete Core Wall Structure

Nonlinear response history analysis (NLRHA) procedure is one of the most precise and accurate numerical method to compute the seismic demands of high-rise structures but is complex, rigorous, and time-consuming and requires a lot of expertise for nonlinear modelling and results interpretation. Therefore, practicing engineers in developing countries like Pakistan still use the simplified analysis procedures to compute the seismic demands. Among the simplified analysis procedures, equivalent lateral force and response spectrum analysis procedures are widely used for the design purpose. However, other procedures have also been proposed in the recent past to accurately capture the higher mode effects in mid-to-high-rise structures. In the current study, results of a forty-story core wall building are used to check the relative accuracy and ease of application of different simplified analysis procedures. Furthermore, a modal decomposition technique is used to separate the modal responses from the NLRHA results, and a mode wise comparison of different demand parameters for different simplified procedures is performed. The current study has been used to clearly identify the reasons of inaccuracies in different simplified procedures. Furthermore, a simplified analysis procedure is proposed to accurately estimate the seismic demands of high-rise buildings and the possible solutions to improve their predictions.

Elastic-displacement-based multi-modal pushover analysis in high-rise core wall buildings

Higher mode effects play a major role in the seismic demands of high-rise buildings. Several recent studies have shown that seismic design demands such as design shear and bending moment in high-rise buildings cannot be predicted by the conventional code-based response spectrum analysis procedure. These can be determined by the more rigorous and accurate non-linear response history analysis procedure, but this procedure is computationally very extensive and time consuming. Yet a non-linear static pushover analysis cannot account for higher mode effects. Therefore, the applicability of a multi-modal pushover analysis (MMPA) procedure using elastic target displacement to cases of 20- 30- and 40-storey high-rise reinforced concrete core wall buildings is investigated in this study. The results obtained by the elastic displacement MMPA (EDMMPA) procedure are compared with those obtained from non-linear analysis. The comparison shows that EDMMPA can satisfactorily estimate the design shear force, bending moment and deformation demands with a variation of 10–20%. Thus, this computationally less demanding analysis can serve as a base line for preliminary design of high-rise reinforced concrete core wall buildings.

Numerical simulation of solar-driven Kalina cycle performance for centralized residential buildings in Iran

ABSTRACTThe building sector is responsible for most of the worldwide electrical energy consumption, having surpassed both the industry and transportation sectors. In this article, a detailed thermodynamic model was proposed for a solar-driven Kalina cycle with an auxiliary superheater to meet the electrical demands of high-rise buildings in Iran’s climatic condition. A combination of correlations characterizing the Gibbs free energy of an ammonia–water mixture was utilized to describe the behaviour of the working fluid. Then an energy analysis of the cycle was studied to solve the system state points as well as the system performance. So its maximum monthly power generation is estimated. A long-term balance is considered between the electricity production and consumption for residential sectors based on the available 10-year recent data for 113 suitable sites. The energy consumption of residential buildings in each province is averaged to calculate the energy consumption of a typical building in that province. Then, the results were shown in terms of solar electrical coverage for each site. The Kalina solar system was able to cover the annual electricity demand of a residential building of at least 20.34% for Hormozgan and at most 164.36% for Isfahan.

일방향 중공 하프슬래브와 일반 중공슬래브의 휨성능 평가

Hollow slab and half slab are applied to many structures in accordance with increase of demand for high-rise buildings because of recent phenomenon of urban overcrowding. In case of using a hollow slab as flooring system, the weight of slab would be reduced so that economical construction could be possible. Using the half slab in floor system makes the deflection of half slab relatively less than general slab as well as it is more advantageous for minimizing cracking. So if these two systems apply at the same time, the better floor system could be created due to the advantages of them. Accordingly, a few researches are conducted about hollow half slab which has advantages of these two floor systems. Therefore, in this study, the flexural capacity of one-way hollow slab and one-way hollow half slab are analyzed and compared for usability of one-way hollow half slab.

Behavior of plate-to-circular hollow section joints of 600 MPa high-strength steel

While the recent high demand for high rise buildings has led to the development of high-performance and high-strength steels, the requirements for structural-performance steel for such buildings have been raised as engineers recognized the potential wreak damage that an earthquake could cause on a tall building. Many studies on high-strength steels have explored such requirements, but appropriate design equations are needed for the case of hollow structural section (HSS) due to the design equations that limit the maximum yield stress up to 360MPa in the design codes (AISC, 2011; KBC, 2009). This study investigated the behavior of 600MPa plate-to-circular hollow section joints subjected to applied moment and shear force by experiment and finite element analysis (FEA), and the results are compared with current design equations. The nominal strength of AISC (2005) (or KBC (2009)) overestimated the tested strength in the range between 105% and 137%. It is found that the nominal strength equation of AISC (2011) is reasonably revised in comparison to those of other design codes.

고강도 원형강관의 길이방향 거셋플레이트 접합부 실험 및 해석

초고층 빌딩의 수요가 증가함에 따라 고강도 강관의 수요 또한 함께 증가하고 있다. 이에 고강도 고인성의 600MPa급 강관의 접합부 내력 연구가 필요하게 되었다. 또한 현행국내기준에는 강관의 경우 항복응력 360MPa 이하에 설계식을 적용하도록 되어 있다. 즉, 고강도강재를 이용한 600MPa 강관의 경우 현행기준을 적용할 수 없으므로 600MPa급 고강도 강관의 거셋플레이트 접합부의 내력실험 및 유한요소해석을 통하여 기존 설계식의 적용가능성을 조사하고 접합부의 거동을 연구하고자 한다. 특히, 본 논문에서는 원형강관에 길이 방향으로 거셋플레이트가 접합된 접합부에 횡력(수평력)이 작용하였을 때의 거동을 다루었다. 유한요소해석 및 실험결과를 설계식과 비교해보면, 고강도 강재에서는 기존의 설계식들이 56~79%로 과소평가되었다. With the increase in the demand for high-rise buildings, the use of high-strength steel has likewise increased. Thus, it has become more necessary to study the resistance force of the high-strength hollow structural section (HSS) joint of 600MPa. Additionally, the current design equation in Korea limits maximum yield stress at 360MPa in the case of HSS. In other words, since the current specification does not apply to HSS of 600MPa, this study aims to investigate the applicability of design equations as well as examine the behavior of the connection through the experiment and finite element analysis (FEA) of the plate-tube connection of 600MPa. In particular, this paper presents the behavior of joints with the gusset plates welded in the longitudinal direction of the circular hollow section (CHS) when the joints are subjected to lateral force. Comparing design equations with the results of FEA and the test, existing design equations are underestimated to be 56~79% in the case of high-strength materials.

대형 시스템 거푸집 공법별 장단점 비교에 관한 연구

Recently, as a result of the economic growth, the concentration of population towards the cities and the rise in land prices, the demand for high rise buildings has increased significantly, the trend to build high rise buildings such as the mixed-use development buildings by the domestic construction companies continues. It's very important what kind of form work system is applied on the Core Wall of the high rise buildings to determine the economic efficiency for the whole project. That's because the appropriate selection of the Formwork system enables the construction cost lower, makes the good quality of the finished concrete, reduces the construction period, assurance of safety, and further more, it enables to achieve the successful performance of the projects. Therefore, this research, after comparing the strength and the weakness between the construction methods, focus the point to provide a builder the basic data to choose the right Formwork method.