Concrete High-rise Buildings Research Articles

Comparative Analysis of Seismic Design Standards for Structures and Safety Standards for High-rise Concrete Building Structures

The core of this study is the comparative analysis of I S. 1893 (Part One): 2016 Edition (Code for Seismic Design of Structures) and I S. 16700:2017 (Code for Safety of High rise Concrete Building Structures). In addition, the study aims to uncover the key factors that contribute to poor performance of buildings in earthquakes, with the aim of improving the safety performance of structures in earthquakes in the future. As a research case, we selected a specific reinforced concrete moment shelving frame (SMRF) building at Jabalpur Airport. The building structure was modeled and analyzed using SAPpro V20i software. According to software calculations, we obtained the time history analysis results of the structure in two directions and ensured that they comply with the two Indian standards mentioned above. Subsequently, by comparing the structural responses under the two standards, we evaluated the significant differences in foundation shear force, displacement, and mass participation. The research results indicate that compared to I S. 1893 (Part One): 2016, following I S. The performance of the 16700:2017 structure in earthquakes is relatively poor.

Data-driven prediction of natural period for existing RC high-rise buildings using probabilistic machine learning methods

The natural period of existing reinforced concrete (RC) high-rise buildings is a fundamental structural parameter for dynamic analysis and condition assessment, while the estimation of such structural characteristic is an important task for life-cycle maintenance. A commonly adopted approach for predicting natural periods involves the use of design-oriented empirical formulas. However, as shown by real-world observations in both this study and others, these formulas with limited building features may not fully capture the complexity and uncertainty of the natural period for existing buildings. Therefore, it is desired to develop an alternative method that is both feature-based and data-driven, to predict natural periods accurately. This study proposes a feature-based probabilistic machine learning method to determine the natural periods and quantify the uncertainty intervals of the predictions for existing RC high-rise buildings. Specifically, the proposed method comprises a random-forest method using quantile regression. Through in situ measurements and an extensive literature review, a database comprising over 500 actual records was constructed, including the building features and their dynamic properties. The results show that the proposed method achieves a coefficient of determination of 0.96 and an uncertainty interval confined within 20 % for the test set. These findings indicate that the proposed method may be both more accurate and reliable. Furthermore, an in-depth investigation into the model interpretability was conducted to reveal the relative importance of different building features. The analyses indicate that the building height emerges as the most crucial feature, while the building width and its lateral resistant system may also demonstrate noticeable influence on predicting natural periods.

Wind-related structural stiffness and stiffness reduction factors

One of the most important parts of a building is its columns. When columns are destroyed, it can lead to the destruction of other structures or be the major cause of the destruction of the whole structure. Building stiffness is a very important factor when looking at how structures behave because it affects how buildings vibrate and, by extension, how much horizontal wind they can handle. It is possible to be more specific about how to plan high-rise buildings that are subject to wind loads by looking at how buildings behave when their structural stiffness decreases. The objective of the study is to investigate through the effects if reinforced concrete buildings reduce stiffness and how that changes how wind affects the structure. The author of this study looks at how reinforced concrete high-rise buildings behave. The results will be used to look at changes in the horizontal displacements and internal forces in buildings so that project design suggestions can be made.

Study on Seismic Performance of Reinforced Concrete High-Rise Building with Buckling Restrained Braces Dissipation Devices

Performance-based Seismic Engineering is the modem approach to Earthquake Resistant Design to control lateral deflection and inter-story drifts. It is a significant challenge to overcome in the execution of high-rise buildings. Since structures are subjected to lateral loads, the Utilization of dissipation devices such as the bracing, shear wall, and dampers are a possible method to enhance the structural performance of the high-rise building under load cases. These cases are varying to static and dynamic ones as Response Spectrum. Properly designed and detailed structures with dissipation devices have exhibited excellent performance during a severe earthquake. Lateral forces due to will be resisted in its plane. In continuation studies of reinforced concrete structure compared to the absorbing devices, Three essential reinforced concrete buildings were taken for analysis G+ 30 floors to cover the broader spectrum of high-rise building construction. Software ETABS carried out seismic analysis through Response Spectrum Analysis. The result highlights how structural damper systems perform much better than other systems with accuracy and exactness through the parameters of Displacement, Drift, Base shear, and Stiffness. Damper structures are more suitable for high-rise buildings and earthquake zones due to this study's results; maximum height of systems could be possible, which must be economically less expensive than steel structure of the same height.

Progressive Collapse Evaluation of a Reinforced Concrete High-rise Building Designed According to Turkish Earthquake Code

In this study, a numerical progressive collapse response evaluation was performed on a 40-story high-rise building designed according to the Turkish Earthquake Code of 2018 (TEC-2018). The alternate path method specified in the General Services Administration of 2016 (GSA2016) and the Unified Facilities Criteria (UFC 4-023-03) was used for the evaluation. A total of 18 scenarios were investigated for column and shear wall removals. In the cases where hinges were observed, the extent of damage was evaluated using the performance criteria given in the Turkish Seismic Code and the American Society of Civil Engineers (ASCE) 41-17. In this study, the most damage was observed when the corner column was removed at the bottom floor, while the least damage was observed on the shear walls close to the center and core of the building. For all the scenarios evaluated, no collapse was observed. The study deduced that the high-rise building designed according to TEC-2018 showed sufficient resistance to progressive collapse.

Wind-Related Structural Stiffness and Stiffness Reduction Factors

One of the most important parts of a building is its columns. When columns are destroyed, it can lead to the destruction of other structures or be the major cause of the destruction of the whole structure. Building stiffness is a very important factor when looking at how structures behave because it affects how buildings vibrate and, by extension, how much horizontal wind they can handle. It is possible to be more specific about how to plan high-rise buildings that are subject to wind loads by looking at how buildings behave when their structural stiffness decreases. The objective of the study is to investigate through the effects if reinforced concrete buildings reduce stiffness and how that changes how wind affects the structure. The author of this study looks at how reinforced concrete high-rise buildings behave. The results will be used to look at changes in the horizontal displacements and internal forces in buildings so that project design suggestions can be made.

Application of Capacity Spectrum Method (CSM) for non-symmetrical reinforced concrete high-rise buildings as a tool for seismic design

The development of earthquake resistance design of structures in the last decade has been critically changing from strength and ductility to performance criteria, where the structure is decided for various levels of structural performance. To understand the structural performance because, at time, a large earthquake load on the structure will experience structural yielding, non-linear analysis with the capacity spectrum method will be performed. The relationship between roof displacement and base shear force is described by a curve that describes the structural capacity is a capacity curve. To determine the behavior of the structures under review for a given earthquake intensity, the capacity curve is then compared with the performance demand based on various earthquake intensities. The results of the case studies for reinforced concrete portals non-symmetrical 3D concluded that the convergence obtained at the point of the structure performance is and . The displacement results for the actual structure () were 286.71 mm and building base shear coefficient was 15.46 %.

PRINCIPLE STRESS IN SHEAR CAPACITY

The design and construction of reinforced concrete high-rise building structures are currently changing for the better, this is due to technological advances in the base materials of concrete that leads to a higher quality. A higher quality concrete in multi-story buildings can reduce the cross-sectional dimensions of lateral resisting elements (earthquake forces). Normal concrete is formed from aggregates (coarse + fine) and paste (a mixture of cement, sand, water, and additives) in general. High-quality concrete is achieved through the use of innovative materials such as steel fiber. Additionally, to form ultra-high concrete, it is made to be close to homogeneous. For this reason, the use of coarse aggregates is eliminated, hence fine aggregates can blend perfectly with cement and other innovative ingredients to form a concrete paste with higher strength than coarse aggregates. Concrete structural elements cannot be separated from shear problems. Shear forces generally combine with bending, torsion, and axial forces. Therefore, it is important to understand the interaction between shear and other forces.

The first high-rise concrete modular integrated construction building in Hong Kong

A new multi-award-winning development of high-rise living quarters for firefighters in Hong Kong, China has been successfully delivered using modular construction. Created from 3726 factory-made concrete modules, it is the first high-rise concrete building development in the region to adopt the ‘modular integrated construction’ method. This paper describes the modular construction process, the NEC-based procurement approach and the innovative technologies used in the development’s design and construction, all of which contributed to a highly efficient and sustainable solution.

Study on Empirical Formulas and Distribution Ranges of Vibration Periods in High-Rise Reinforced Concrete Constructions

ABSTRACT China is now undergoing the largest and fastest urbanization process in the world, developing various reinforced concrete high-rise buildings during this process. Most high-rise structures are constructed in densely populated and economically active areas and earthquakes pose a potential possibility of serious economic loss and casualties, which cannot be ignored. This paper conducts on-site dynamic tests on 129 high-rise RC buildings in eastern China by utilizing ambient vibration measurement. Fundamental vibration periods, second vibration periods, and third vibration periods are statistically analyzed in translational directions based on two high-rise building types: shear wall slab building and shear wall tower building (including framed shear wall structures and framed tube structures). After fully considering building usage conditions and comparing the fitting formulas in existing codes, fitting empirical formulas of the vibration periods in two translational directions based on the above structural types are given. The ratio distribution ranges of vibration periods are calculated by utilizing the vertex displacement method, concentrated mass method, and Rayleigh-Ritz energy method. In addition, by analyzing the vibration period ratio in horizontal directions of 543 high-rise RC buildings, different ranges are distinguished as well as suggested boundaries are given. The conclusion of this paper provides a reference and convenient method for future on-site dynamic testing and a new proposal is provided to the empirical formula of vibration period in the current building seismic design code.

Size optimization design of members for shear wall high-rise buildings

Structural optimization can lead to efficient designs for high-rise concrete buildings. However, the high computational cost of the structural analysis step hinders its application in practical cases. With regards to this problem, a novel hybrid optimization framework is developed in this study. Discrete variables, code-stipulated constraints and other construction requirements under multiple loading scenarios are considered. The hybrid optimization framework contains two steps: in the first step, a computationally efficient approximation of the optimization formulation is constructed using a combined response surface methodology (RSM). Combining all the design constraints, three sub-optimization problems are proposed based on the relaxation model of the original problem to update the response surface model in the near-optimum region. When the response surface model has sufficient accuracy in the near-optimum region, in the second step, a discrete Particle Swarm Optimization (PSO) technique is applied to search for the optimal solution utilizing the response surface model. By integrating the commercially available ETABS, a dedicated optimization software with an independent interface is developed and details for practical software development are included in this paper. Three examples of high-rise concrete building design are presented to demonstrate the effectiveness of the proposed optimization framework, and the results are compared to those of a general PSO algorithm. It is shown that, compared to the conventional design approach, a 14.3% reduction in material usage is achieved by the hybrid optimization framework. Additionally, the proposed framework significantly improves the computational efficiency compared to PSO. This methodology can therefore be used by engineers to optimize member sizes for high-rise buildings so that stable and sustainable designs can be achieved.

Analysis of Seismic Structure Design of High-rise Concrete Buildings

Analysis of Seismic Structure Design of High-rise Concrete Buildings

Simultaneous Effect of Seismic Intensity and Shear Wall Design on the Cost of High-Rise Buildings in Saudi Arabia

This research study intends to investigate the influence of shear wall design and seismic intensities on the potential cost of Reinforced Concrete (RC) high-rise buildings in Saudi Arabia. The seismic intensities of the proposed locations vary from relatively low to relatively high. Conventional and ductile design methods are considered for designing the shear walls in different locations. The influence of these selected locations and employed design methods associated with the anticipated cost is numerically computed and quantified. The three-dimensional finite element models are created using the available structural software package ETABS. Cost analyses are performed and obtained for the conventionally designed buildings in the considered different locations. The corresponding cost analyses considering the ductile design of shear walls are also computed for all the considered models. Reinforcement steel material and labor costs are utilized to determine the total cost of the shear walls. Other cost elements such as concrete, formwork, machinery, finishing, etc. are not included. The relation between spectral accelerations and required reinforcement for each shear wall design is made. Sensitivity analysis, using @Risk software, with respect to the labor cost is performed to cover the expected risk during the COVID-19 Pandemic.

Analysis on Design Points of Seismic Structure of High-rise Concrete Building

Analysis on Design Points of Seismic Structure of High-rise Concrete Building

A practical discrete sizing optimization methodology for the design of high-rise concrete buildings

PurposeIn this article, a practical design methodology is proposed for discrete sizing optimization of high-rise concrete buildings with a focus on large-scale and real-life structures.Design/methodology/approachThis framework relies on a computationally efficient approximation of the constraint and objective functions using a radial basis function model with a linear tail, also called the combined response surface methodology (RSM) in this article. Considering both the code-stipulated constraints and other construction requirements, three sub-optimization problems were constructed based on the relaxation model of the original problem, and then the structural weight could be automatically minimized under multiple constraints and loading scenarios. After modulization, the obtained results could meet the discretization requirements. By integrating the commercially available ETABS, a dedicated optimization software program with an independent interface was developed and details for practical software development were also presented in this paper.FindingsThe proposed framework was used to optimize different high-rise concrete buildings, and case studies showed that material usage could be saved by up to 12.8% compared to the conventional design, and the over-limit constraints could be adjusted, which proved the feasibility and effectiveness.Originality/valueThis methodology can therefore be applied by engineers to explore the optimal distribution of dimensions for high-rise buildings and to reduce material usage for a more sustainable design.

Novel discrete diaphragm system of concrete high-rise modular buildings

Modular high-rises are attractive for metropolises, but few applications exist, partly due to the lack of knowledge about their lateral behaviors. Existing concrete modular high-rises usually adopt a time-consuming and labor-intensive cast-in-situ concrete layer on modules to satisfy the continuous rigid diaphragm assumption. This study aims to develop an innovative discrete diaphragm system for concrete modular high-rises without a cast-in-situ concrete layer. A private residential building in Hong Kong (HK) was selected as the case building, in which the novel horizontal and vertical connection designs were proposed. A simplified spring model considering in-plane axial and shear behaviors was proposed to simulate the horizontal connections. A three-dimensional finite element model of the case building with discrete diaphragms was established using the spring model. A parametric study was conducted to examine the influence of horizontal connections on the deflection and natural periods of the case building under the HK code-specified wind loads. A comparative study was conducted using five cases with different connection stiffness sets to systematically investigate the influence of horizontal connections on the structural responses of the case building under the wind loads. Results show that the discrete diaphragm system is feasible for concrete modular high-rises in HK. Effects of horizontal connections on the lateral behavior of concrete modular high-rises should be considered in the structural design when the discrete diaphragms are adopted. This study breaks through the continuous rigid diaphragm assumption and proves that appropriate flexible horizontal connections are a feasible option for concrete modular high-rises under wind loads.

Towards understanding, estimating and mitigating higher-mode effects for more resilient tall buildings

Rapid urbanization has resulted in increased demand for tall buildings in many large and medium-sized cities around the world. Current code-based standards for seismic design are primarily aimed at minimizing life-safety risks under major earthquakes. While reinforced concrete (RC) high-rise buildings designed following current code requirements are expected to achieve collapse-prevention, the contribution of higher modes of vibrations to the dynamic response of these structures can produce seismic demands significantly larger than those obtained from prescriptive code-based procedures, causing unexpectedly higher structural and non-structural damage to these buildings. These imply considerable costs associated with the loss of residences and business operations as well as the post-earthquake recovery of cities. This paper presents a concise review of the current state-of-the-art and state of research pertaining to the understanding, estimation and mitigation of higher-mode effects on the seismic response of tall and slender RC structures. The paper is organized into four main foci: (1) analytical studies on understanding and quantifying higher-mode effects, (2) available experimental work on this topic, (3) advances in code practices in accounting for higher-mode effects in seismic design of RC tall buildings, and (4) recent developments in innovative systems intended to mitigate higher-mode effects in RC tall buildings. The paper concludes by briefly summarizing future challenges facing the construction of earthquake-resilient RC tall buildings that are essential in building resilient cities of the future.

Assessment of Strength Reduction Factor on Concrete Moment Frames According to the New Venezuelan Seismic Code

Nonlinear static analysis is a validated tool for the seismic evaluation of existing and new structures, specifically for reinforced concrete buildings. In order to assess the performance of reinforced concrete frames designed according to the new Venezuelan seismic code, configurations of low-, medium-, and high-rise concrete buildings are subjected to 20 different load patterns considering the nonlinear behavior according to FEMA P695. A total of 140 concrete frame models were analyzed using modal response spectrum analysis and nonlinear static pushover analysis. The parameters considered for analyzing the models were the response reduction factor (R), the overstrength factor (RΩ), and the ductility factor (Rµ). The results showed a performance controlled by ductile failure mechanisms in low-rise models unlike combined failure mechanisms with columns with plastic hinge in high-rise models. Reduction factor values between 4 and 14 were obtained. In addition, the pushover curves were affected by the load patterns; therefore, it was necessary to identify the representative patterns, refusing the rest of the patterns. A statistical adjustment was performed using a log-normal distribution. The strength reduction factor specified in the new Venezuelan code was higher than the values obtained for the 95% confidence levels according to the distribution assumed in the reinforced concrete frames models. Finally, the strength reduction factor more representative is R = 4.

Module equivalent frame method for structural design of concrete high-rise modular buildings

Despite the increasing adoption of modular construction worldwide, it is still largely limited to low-to-medium-rise buildings. One of the main reasons is the knowledge gap regarding the structural design of modular high-rises. This provides a significant opportunity for research and development as high-rise buildings are more competitive in metropolises. This study aims to develop a novel module equivalent frame method (MEFM) for structural design of concrete high-rise modular buildings based on the concept that modules bear vertical loads and transfer lateral loads to cores that mainly resist such loads. A typical Hong Kong high-rise public residential building was used for the case study. The modular structural design scheme was considered as the case study building based on three aspects, i.e. floor plan, connection types, and modular components. A new procedure was established to determine the strength grades of module walls for unifying their thickness at different stories while satisfying the structural performance. An analytical method was established to determine an equivalent frame system with significant vertical resistance and limited lateral resistance to model the walls within a concrete module according to the equivalent principle of concrete volume, size, and shape requirements. The structural responses of the 30-, 40-, and 50-story cases under wind load were calculated using the developed MEFM and compared with the results using the ‘equivalent shear wall method’, which considers the module walls as shear walls. Results show that the MEFM is feasible for achieving structural design solutions of concrete high-rise modular buildings. Moreover, the MEFM is found to be more suitable for the 30-story case than for the 50-story case owing to the reduced precast ratio with an increase in building height. Furthermore, the MEFM is more appropriate than the equivalent shear wall method for simulating module walls because it can better balance the structural safety, material consumption, and precast ratio. The procedure for determining the strength grades of module walls can reduce the lifting weight owing to the higher strength concrete used in the module walls at lower stories. The proposed modularisation scheme is typical and representative and can be adopted for standard flat types of high-rise public residential buildings in Hong Kong.

Assessment of the impacts of building materials on the reduction of CO2 emissions from high-rise commercial buildings in Hong Kong

Based on data collected in 20 A-level high-rise commercial concrete buildings in Hong Kong, the research successfully established a probability density function model, which is used to describe the carbon emissions profile of a commercial building. Results indicate that the superstructure of a commercial building, on average, had a footprint of 226.65 kg CO2/m2 and 10.6 kg CO2/m2 separately in the material use stage and transportation stages. It also evaluates the carbon emissions of various building elements and divides them into three levels according to the magnitude of their contribution. The results show that upper floor construction and external wall in Tier 1 contribute nearly 80% of emissions and should be of great concern. In addition to the probability density function model, a regression model was also successfully established in the study to predict carbon emissions. Research has shown that building layers and gross floor area can predict carbon emissions per unit area, and there is a positive relationship between the independent variable and the dependent variable. The regression model can help building designers determine design options to reduce carbon emissions in the early stages of design.