High-rise Reinforced Concrete Buildings Research Articles

Evaluation of the Nonlinear Seismic Responses of High-Rise Reinforced Concrete Buildings with Different Foundations and Structural Plans—Considering Soil-Structure Interactions

Evaluation of the Nonlinear Seismic Responses of High-Rise Reinforced Concrete Buildings with Different Foundations and Structural Plans—Considering Soil-Structure Interactions

Residual design life-based evaluation of structural retrofitting on high-rise reinforced concrete buildings

The deteriorating structural performance of aging high-rise reinforced concrete (RC) buildings has brought increasing attention to the necessity of retrofitting in developed regions. In this context, the present paper introduces a novel approach by reversing the conventional service life-based structural design procedure. The proposed approach establishes a residual design life evaluation framework, enabling a comprehensive assessment of the performances of existing RC buildings both before and after retrofitting. This assessment framework takes into account various load scenarios, including wind and earthquake forces, etc., and yields an intuitive index based on design codes, termed "residual design life", which serves as valuable information for decision-makers. To exemplify the framework's application, a case study involving a high-rise RC building is presented. Initially, the influence of the adopted design codes on the residual life of the aging building is investigated. Subsequently, three commonly employed structural-level retrofit methods, namely steel bracing, RC wall addition, and exoskeleton, are examined. The findings reveal that the residual design life of the existing building decreases as the adopted design code transitions from an outdated version to the current one. However, the implementation of structural-level retrofit interventions proves highly effective in enhancing the building's residual life, particularly when failure is primarily governed by column capacities and storey drift. Nonetheless, it should be noted that certain structural-level interventions may increase the load on adjacent beams, potentially leading to a negative impact on the building's residual life when the condition of the beams becomes the predominant factor. Furthermore, the obtained residual life of the retrofitted building could be used to assist in conducting life-cycle analysis and further investigations and contribute to the understanding regarding structural performance and safety in the built environment.

Seismic Response Analysis of High-Rise Reinforced Concrete Buildings Using Outrigger System

Seismic Response Analysis of High-Rise Reinforced Concrete Buildings Using Outrigger System

Performance of RC cast-in-place buildings during the November 26, 2019 Albania earthquake

This paper documents performance of cast-in-place reinforced concrete (RC) buildings in the Durrës municipality during Albania earthquake of November 26, 2019 (MW 6.4). Both mid- and high-rise RC buildings were affected by the earthquake, experiencing structural and/or non-structural damage and even collapse in some cases. The authors performed a reconnaissance study after the earthquake and were involved in seismic assessment of buildings in the affected area. Besides the observations related to physical damage of RC buildings, the paper also presents results of a statistical analysis of damaged RC buildings in the Durrës municipality. The discussion in the paper is focused on damage patterns and failure mechanisms that are relevant for the seismic response of RC structures. Most common damage pattern observed after the earthquakes was related to masonry infill walls, which experienced damage and failure in some cases, and affected the performance of adjacent RC columns due to the infill/frame interaction. Taller RC framed buildings (10 storeys and higher) were expected to have RC shear walls; however, these walls were reportedly absent in the damaged buildings of this type. In some cases, masonry infill walls (instead of RC shear walls) were used in the elevator shaft areas, which resulted in inadequate seismic performance. A case study has been presented to illustrate seismic behaviour of mid-rise and high-rise cast-in-place RC buildings in the November 2019 earthquake, and is based on post-earthquake field observations and a detailed seismic assessment of two earthquake-damaged buildings. Finally, relevant lessons and recommendations are presented in light of the observed performance of RC buildings.

Examining progressive collapse robustness of a high-rise reinforced concrete building

To examine high-rise building robustness to sudden column removal, progressive collapse studies of a 13-story flat-slab reinforced concrete (RC) core-wall building system were completed in this study. Two buildings on the University of Nebraska-Lincoln (UNL) campus, Cather and Pound Halls, were demolished in December of 2017. UNL researchers were given unique access to the building sites to assess their response before, during, and after the event. Prior to demolition, accelerometers were placed throughout both buildings, and ambient measurements were conducted to establish natural frequencies and mode shapes. The response of both buildings during controlled demolition was recorded and analyzed using time histories from the accelerometers. Controlled demolition initiated with sequential blast detonation at selected column sections that resulted in progressive collapse. A detailed 3D nonlinear numerical model of Pound Hall was developed using LS-DYNA to mimic the progressive collapse. The accuracy of the building model was evaluated via comparisons between (i) simulated and measured building ambient frequencies and modes; and (ii) displacement and video recorded during the full-scale demolition. The validated model was then used to further investigate damage scenario effects on the robustness of high-rise RC buildings caused by sudden removal of columns at various locations on the ground floor. The study results can be used to develop and calibrate the nonlinear numerical model for analyzing high-rise building progressive collapse behavior and can help provide information that may improve new and existing flat-slab RC core-wall building robustness against progressive collapse.

Chinese High Rise Reinforced Concrete Building Retrofitted with CLT Panels

Cross laminated timber (CLT) panels have been gaining increasing attention in the construction field as a diaphragm in mid- to high-rise building projects. Moreover, in the last few years, due to their seismic performances, low environmental impact, ease of construction, etc., many research studies have been conducted about their use as infill walls in hybrid construction solutions. With more than a half of the megacities in the world located in seismic regions, there is an urgent need of new retrofitting methods that can improve the seismic behavior of the buildings, upgrading, at the same time, the architectural aspects while minimizing the environmental impact and costs associated with the common retrofit solutions. In this work, the seismic, energetic, and architectural rehabilitation of tall reinforced concrete (RC) buildings using CLT panels are investigated. An existing 110 m tall RC frame building located in Huizhou (China) was chosen as a case study. The first objective was to investigate the performances of the building through the non-linear static analysis (push-over analysis) used to define structural weaknesses with respect to earthquake actions. The architectural solution proposed for the building is the result of the combination between structural and architectonic needs: internal spaces and existing facades were re-designed in order to improve not only the seismic performances but also energy efficiency, quality of the air, natural lighting, etc. A full explanation of the FEM modeling of the cross laminated timber panels is reported in the following. Non-linear FEM models of connections and different wall configurations were validated through a comparison with available lab tests, and finally, a real application on the existing 3D building was discussed.

Characterization of High-Rise Reinforced Concrete Buildings Located in Antofagasta, Chile, by Means of Structural Indexes

This study aims to characterize a series of high-rise reinforced concrete wall buildings located in Antofagasta, Chile, by means of a set of structural indexes commonly used in professional activities in our country and recommended by researchers. To this effect, a total of eight buildings was analyzed, from which, based on their architectural plans and engineering drawings, a series of properties was determined, such as wall and floor area, among others. Additionally, a modal spectral analysis was carried out according to the current Chilean regulations (NCh 433Of.1996Mod.2009 and DS 61) by means of the ETABS software. Next, eleven structural indexes were selected and determined, which are related to stiffness, structural redundancy, and ductility, with the purpose of making a seismic qualification. The obtained values indexes provide information about the expected structural performance of the buildings under a major seismic event. Finally, correlations between the different indexes were established.

Design criteria for the folding implosion of high-rise RC buildings

Blasting is an efficient method for demolishing high-rise buildings and structures. If the collapse scope of a building to be blasted is insufficient controlled building implosion technology is preferred. However, for the conventional implosion, there is a lot of pre-weakening work that has to be done, and it is almost impossible to demolish the high-rise thin wall structures such as reinforced concrete (RC) chimneys. Therefore, a folding implosion method is proposed. In this method, several wedge-shaped notches should be blasted out in the high-rise building or structure, then these notches will turn to “plastic hinges”, meanwhile, the building or structure will turn to a folding kinematic chain, and the segments will overlap each other after falling down. For this method, some design criteria for the main parameters such as the position, initiation sequence, and initiation time delay of blast notches are proposed. The multi-body dynamics models for bi-folding implosion and tri-folding implosion are deduced to analyze the folding motions and rationality of the blasting plans. In two implosion cases, the design criteria and kinematics models are validated.

A Practical Compensation Method for Differential Column Shortenings in High-rise Reinforced Concrete Buildings

High-rise reinforced concrete buildings have technical, economic and environmental advantages for high density development and they have become a distinctive feature for densely populated urban areas around the world. For this purpose, structural design of high-rise reinforced concrete buildings have become forward and particularly serviceability requirements gained more interest. Differential shortening of vertical members is one of the serviceability requirements; however, only a limited number of studies exist. In this study, a practical compensation method was proposed for the differential shortening of columns and shear walls in high-rise reinforced concrete buildings. In the proposed compensation method, vertical members were grouped and the total error was aimed to be minimized by penalizing the higher shortening differences in the groups to simplify the process of building construction. In order to validate the proposed method, a 32-storey high-rise building that was built in Izmir Turkey was investigated considering both the construction sequence and time-dependent effects as shrinkage and creep. Vertical shortening of columns and shear walls in the tower part of the building were calculated. Uniform-grouped compensation method and the proposed penalized errors compensation method with using L1-norm and L2-norm were applied for differential shortenings of columns and shear walls with considering different numbers of member groups. The magnitude of errors for each compensation method was presented and evaluated. Results of the numerical study reveal that the proposed penalized errors compensation method was capable of determining the compensation errors by minimizing the maximum errors efficiently.

Yüksek Katlı Betonarme Binalarda Yanal Yük Dayanım Sistemleri

Verimli ve ekonomik bir yüksek bina, yapısal sistemin seçimini etkileyen önemli faktörler tam olarak anlaşılmadan ve bu sistemin mimari, mekanik ve diğer yönlerle nasıl bir ilişki içinde olacağı bilgisi olmadan tasarlanamaz. Bu çalışmada, farklı tipteki yanal yük dirençli sistemlerin (moment çerçeve sistem, perde duvarlı sistem, perdeli-çerçeveli sistem ve tüplü çerçeve sistemler) sismik yükler ve rüzgâr yükleri altında yapısal tepkilerini karşılaştırmak için bir yapısal analiz programı olan ETABS kullanılarak yapısal analizler yapılmıştır. Bina 625m² (25m x 25m) alana sahip 28 kattan oluşmaktadır. Tüm yanal yük dirençli sistemler için kat deplasmanları hesaplanmıştır. Yanal yük dirençli sistem tipleri arasında perdeli-çerçeveli sistem, bu yükseklik için çok uygun bir yapısal tepki göstermiş ve sınır değerlerini aşmamıştır.

Seismic fragility assessment of existing reinforced concrete buildings in Patna, India

Assessment of seismic fragility of reinforced concrete (RC) buildings requires appropriate consideration of uncertainty in aleatory and epistemic sources. Aleatory uncertainty is typically attributed to randomness in ground motion records, while epistemic is due to the uncertainties in structural modelling. The present work focuses on obtaining the variability functions and fragility curves by considering those uncertainties for low, mid and high rise RC buildings in Patna, India, which is a region of high seismicity.Modelling uncertainties requires consideration of material, geometrical, and design as random parameters. These parameters mainly comprise material strength, storey height, plan, typology, design provisions, and various irregularities. In this study, the selection of the random parameters is purely based on the investigation of buildings in the Patna region. Considering the multiple combinations of random parameters, the buildings are modelled and analysed using nonlinear static (NLS) pushover analysis. The monotonic load in a triangular pattern is applied for NLS analysis to get pushover curves. The pushover curves are subsequently converted into capacity curves considering the dynamic characteristic of the first mode of vibration. The obtained capacity curves are utilised to derive the variability in the capacity spectrum for different categories of RC buildings. Subsequently, variability due to randomness in ground motion records is determined by generating several artificial (comprising near field and far field) ground motions considering the seismotectonic map of the region.Thence, by accounting for both the uncertainties, lognormal variability functions are determined, and seismic fragility assessment is performed for different building categories in Patna, India. Furthermore, the seismic vulnerability of existing buildings can be determined based on the obtained fragility curve.

Damping and Natural Period Evaluation of Tall RC Buildings Using Full-Scale Data in Korea

In recent years, the main usage of reinforced concrete (RC) structures in Korea has shifted from low-rise residential and commercial buildings to high-rise buildings. Because an increasing number of high-rise RC buildings are being built, especially in coastal cities, which are periodically hit by typhoons, wind-induced motion and the corresponding serviceability issues have attracted considerable attention. Natural period and damping ratio are the most important factors for estimating the design wind load and wind-induced response in the design of tall buildings. However, the Korean Building Code (KBC 2009) does not specify empirical formulae for estimating the natural period and damping ratio for wind design, unlike seismic design. In this study, the damping ratio and natural period of existing concrete buildings in Korea are measured and compared to those obtained using the formulae provided in various codes and research works. Furthermore, design formulae for estimating natural frequency and damping ratio for wind design are proposed based on the measured data. For this purpose, ambient vibration measurement is performed for 58 RC buildings with heights of 24.2–305 m.

Damage Assessment of High-Rise Reinforced Concrete Buildings in Peninsular Malaysia Subjected to Ranau Earthquake

This paper shows the analysis of high reinforced concrete buildings in Ranau that have experienced low intensity intensity earthquakes. This study refers to the performance of five (5) high rise reinforced concrete frame when subjected to a variation of low earthquake intensity analysis with 5% damping ground motion measurements. The IDARC software is used to study structures through nonlinear dynamic analysis. Beam-column points are examined to determine damage to the index and to build damage levels subject to varying seismic load. Result shows the first yielding occurred at 4.82 seconds for the beam element at when 0.05g load applied. Based on the result, all buildings cannot withstand seismic load when goes up to 0.2 ground acceleration. It may have arisen that the building is categorized to the extent of the major damage where there is structural affect and structural affect up to 0.15g intensity.

Energy-based collapse assessment of complex reinforced concrete structures with uncertainties

This paper presents an integrated approach for collapse assessment of complex reinforced concrete (RC) structures regarding the randomness in nonlinear behavior of concrete. The concerned uncertainty is quantified based on a stochastic damage model (SDM) of concrete in which the fracture strain in micro-level is modeled as a Gaussian random field. By integrating the SDM into refined finite element analysis, the stochastic collapse of high-rise RC buildings subjected to strong seismic actions can be numerically simulated. An energy-based dynamic instability criterion in identifying structural collapse is recommended to further assess the structural anti-collapse reliability. Using the criterion, the collapse-resistance performance for a certain structure can be quantitatively evaluated based on the probability density evolution method, by which the randomness propagation across multiple scales of concrete and the transformation of probability structure of structural responses can be fully addressed and represented. Numerical investigation in terms of a prototype RC frame-shear wall structure is carried out. It is indicated that the randomness from concrete may dramatically affect the collapse behavior of the structure, and even lead to entirely different failure modes.

Influence of soil–structure interaction on fragility assessment of building structures

In this work, 3D reinforced concrete (RC) and steel building structures have been considered for studying the effect of soil–structure interaction modelling on the structural fragility assessment of such structures. In particular, three foundation models were considered: fixed model where soil–structure interaction is neglected, spring model with single-node Winkler springs and pile foundation model where soil–structure interaction is simulated using beam and quadrilateral finite elements for the pile and soil numerical simulation, respectively. For the assessment of the structural performance and the influence of the various soil–structure interaction numerical simulation models, fragility analysis is applied by considering four limit-states. For the purpose of the current study 3D, low-, mid- and high-rise RC and steel buildings are studied. The test examples employed in this study were designed first according to Eurocodes 2, 3 and 8 using the SCADA Pro analysis and design software and then nonlinear static analyses were performed for developing the fragility curves. Comparing the outcome of fragility analysis it was observed that for the case of the low- and mid-rise buildings, the structural performance was not affected significantly by the foundation system. However, it was observed that the foundation system contributes considerably to the overall structural performance of the high-rise structures examined.

Seismic vulnerability assessment of high-rise non-ductile RC buildings considering soil–structure interaction effects

Traditionally fragility curves of reinforced concrete (RC) buildings are estimated with the assumption of fixed base structures. The objective of the present research is to study whether soil-structure interaction (SSI) and site effects may affect the seismic performance and vulnerability of reinforced concrete moment resisting frame (MRF) buildings and consequently modify the fragility curves. SSI is modeled applying the direct one-step approach considering either linear elastic or nonlinear soil behavior while site effects are inherently accounted for. To further examine the contribution of site and SSI effects, a two-step uncoupled approach is also applied, which takes into account site effects on the response of the fixed base structure, but neglects SSI effects. Additional analyses are performed investigating the influence of the soil depth and stratigraphy under nonlinear soil behavior on the seismic response and fragility of RC buildings. A 9-story RC MRF designed with low seismic code provisions is adopted as a reference structure. A comparative dynamic analysis is performed highlighting various trends in the seismic response of the considered SSI and fixed base systems. Fragility curves are derived as a function of rock outcropping peak ground acceleration for the immediate occupancy and collapse prevention limit states for the fixed base and SSI models based on the statistical exploitation of the results of incremental dynamic analysis (IDA) of the given structural systems. Results show the significant role of SSI and site effects under linear or nonlinear soil behavior in altering the expected structural performance and fragility of high-rise fixed base structures.

Experimental and numerical evaluation of the fundamental period of undamaged and damaged RC framed buildings

This paper deals with the period evaluation of Reinforced Concrete (RC) framed buildings in elastic, yield and severely damaged states. Firstly, period-height relationships either reported in the literature, or obtained from both numerical simulations (eigenvalue analyses) and experimental measurements (ambient vibration analyses) have been examined and compared. Structural types representing low-rise, mid-rise and high-rise RC buildings without earthquake resistant design, widely present in the Italian and European built environment, have been studied. Results have shown high differences between numerical and experimental period values. Period elongation (stiffness degradation) during and after strong ground shaking has been also examined based on results from experimental in situ and laboratory tests performed on some RC framed building structures which suffered moderate-heavy damage. Some comments on the relationship between damage level and period elongation are reported.

Structural Design of 80-Story RC High-Rise Building Using 200 Mpa Ultra-High-Strength Concrete

This paper presents the design of an 80-story reinforced concrete (RC) high-rise building using 200 MPa ultra-high-strength concrete. Static nonlinear push over analyses, Level-1 and Level-2 nonlinear earthquake response analyses and nonlinear wind response analyses were carried out. Based on the three-dimensional static nonlinear analyses of the building subjected to design earthquake loading in two principal directions, the obtained maximum axial load ratio for the first story columns of 200 MPa compressive strength concrete were 0.53 and 0.48, respectively, at the ultimate limit state, which meets the design criterion based on the allowable compressive stress of concrete. The maximum story drift angle obtained under the synthetic wave motion at the construction site was smaller than the design limiting value of 1/100. While yield hinges developed only in some of the short beams, no yield hinge in columns was observed. The maximum ductility of 1.28 obtained in the beams is lower than the design limiting value of 4.0. The maximum story shear force for the level-2 wind load was almost half that of the level-2 earthquake load when using the lumped-mass model. The analyses confirmed that the use of 200 MPa concrete enables structural designers to provide the member sections with adequate sizes comparable to that of ordinary high-rise RC buildings. The analytical results showed that the performance of the building satisfies the design criteria for serviceability limits, design limits and ultimate limits.

鉄筋コンクリート高層建物への衝撃荷重に対する応答特性 : その2 中規模の航空機衝突による応答特性(構造)

鉄筋コンクリート高層建物への衝撃荷重に対する応答特性 : その2 中規模の航空機衝突による応答特性(構造)

Damage Control of High-Rise RC Building with Energy Dissipation Device

This paper reports the fact that an energy dissipation device (damage fuse) in its reinforced concrete (RC) frame can upgrade the ability to dissipate the energy created by earthquake excitations. When a damage fuse is applied to an RC frame, the fact that behavior such as cracking of attachment members and flexural yielding of reinforcing bars can reduce the effect of damage control should be taken into consideration, and the validity of performance evaluations of frames with a damage fuse and analysis models should be thoroughly examined in this light. Analysis models of RC frames with a damage fuse were found to effectively demonstrate the restoring force characteristics obtained from test results of horizontal loading. Several high-rise RC building projects have already chosen to use damage fuses to mini-mize serious damage to RC buildings subjected to strong earthquakes.