High-rise Reinforced Concrete Research Articles

A Comparison of the Energy Saving and Carbon Reduction Performance between Reinforced Concrete and Cross-Laminated Timber Structures in Residential Buildings in the Severe Cold Region of China

This paper aims to investigate the energy saving and carbon reduction performance of cross-laminated timber residential buildings in the severe cold region of China through a computational simulation approach. The authors selected Harbin as the simulation environment, designed reference residential buildings with different storeys which were constructed using reinforced concrete (RC) and cross-laminated timber (CLT) systems, then simulated the energy performance using the commercial software IESTM and finally made comparisions between the RC and CLT buildings. The results show that the estimated energy consumption and carbon emissions for CLT buildings are 9.9% and 13.2% lower than those of RC buildings in view of life-cycle assessment. This indicates that the CLT construction system has good potential for energy saving when compared to RC in the severe cold region of China. The energy efficiency of residential buildings is closely related to the height for both RC and CLT buildings. In spite of the higher cost of materials for high-rise buildings, both RC and CLT tall residential buildings have better energy efficiency than low-rise and mid-rise buildings in the severe cold region of China.

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.

Seismic fragility assessment of RC frame structure designed according to modern Chinese code for seismic design of buildings

Following several damaging earthquakes in China, research has been devoted to find the causes of the collapse of reinforced concrete (RC) building sand studying the vulnerability of existing buildings. The Chinese Code for Seismic Design of Buildings (CCSDB) has evolved over time, however, there is still reported earthquake induced damage of newly designed RC buildings. Thus, to investigate modern Chinese seismic design code, three low-, mid- and high-rise RC frames were designed according to the 2010 CCSDB and the corresponding vulnerability curves were derived by computing a probabilistic seismic demand model (PSDM).The PSDM was computed by carrying out nonlinear time history analysis using thirty ground motions obtained from the Pacific Earthquake Engineering Research Center. Finally, the PSDM was used to generate fragility curves for immediate occupancy, significant damage, and collapse prevention damage levels. Results of the vulnerability assessment indicate that the seismic demands on the three different frames designed according to the 2010 CCSDB meet the seismic requirements and are almost in the same safety level.

Identification of Reasons for High Inelastic Seismic Demands in High Rise RC Core Wall Buildings

Recently, the issue of high inelastic seismic demands at severe ground shakings such as MCE level has been highlighted in the conventionally designed high rise reinforced concrete (RC) core wall buildings. Furthermore, it is also found that the MCE level demands obtained from more rigorous non-linear response history analysis (NLRHA) are much greater than the DBE level demands obtained from the response spectrum (RS) procedure. In this study, different factors responsible for the high inelastic seismic demands and large difference between the demands obtained from the RS method and NLRHA are identified. A case study building is analyzed by the RS and NLRHA procedures using DBE response spectrum and the seven MCE spectrum compatible ground motions respectively. The factors which could be apparently responsible for large difference between the demands by the RS and NLRHA method are identified as: overstrength factor, excitation intensities, and different damping ratios. The effect of these factors on seismic demands is quantitatively estimated by performing the NLRHAs at different combination of damping ratios and excitation levels. Apart from three obvious factors, some other factors, which cannot be explained by the NLRHA, are also found to be responsible for the high inelastic seismic demands and large difference between the DBE demands by the RS procedure and MCE demands by the NLRHA procedure. To identify those factors, modal decomposition of the inelastic responses of the case study building using uncoupled modal response history analysis (UMRHA) is in progress.

Structural Behavior of RC Cylinders Confined with High Strength Transverse Reinforcement

The number of high-rise reinforced concrete (RC) buildings is steadily increasing since 1980’s. The use of high strength concrete is indispensible for high-rise RC construction to ensure sufficient strength of the structure. The effect of high strength concrete can be significantly improved by the use of high strength and large size reinforcing bars. The yield strength of transverse reinforcement is limited in the current design codes to prevent possible sudden concrete failure due to over reinforcement. This paper presents the effects of the yield strength of transverse reinforcement and compressive strength of concrete on the structural behavior of reinforced concrete cylinders. Two parameters were considered in this investigation: compressive strength of concrete and the yield strength of transverse reinforcement (472MPa, 880MPa, and 1,430 MPa). Analytical and experimental results indicated that the structural behavior of RC cylinders confined with high strength transverse reinforcement is strongly influenced by compressive strength of concrete.

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.

저층부에 약층과 비틀림 비정형성을 가진 고층 비정형 RC벽식 구조물의 지진응답

최근 우리나라의 대도시에서는 주거와 상업기능을 동시에 갖는 복합용도의 건축물이 많이 건설되고 있는데, 이러한 건물은 대부분 하부골조에서 연층, 약층 또는 비틀림 비정형을 띠게 된다. 본 논문의 목적은 이러한 건물의 지진응답을 실험을 통해 관찰하는 것으로서 1:12 축소모델의 진동대 실험을 통해 다음과 같은 결론에 이르렀다. 1) 구조물의 불확실성으로 인한 우발비틀림을 예측하는 것은 정적해석에 의한 방법보다 동적해석에 의한 방법이 더 타당하였다. 2) 횡운동과 비틀림운동이 연관되어 있을 때, 전도모멘트는 지진방향 뿐만 아니라 지진방향에 수직인 방향으로도 상당부분 작용하였으며, 일반적인 해석프로그램에서 수행하는 모드해석법으로는 이와 같은 거동을 예측하기에 부적절하였다. 3) 모드형상과 BST 다이아그램을 통해 대상구조물과 같은 건물의 주요 진동모드와 파괴양상을 쉽게 예측할 수 있었다. Recently, many high-rise reinforced concrete(RC) bearing-wall structures of multiple uses have been constructed, which have the irregularities of weak(or soft) story and torsion at the lower stories simultaneously. The study stated herein was performed to investigate seismic performance of such a high-rise RC structure through a series of shaking table tests of a 1: 12 model. Based on the observations of the test results, the conclusions are drawn as follows: 1) Accidental torsion due to the uncertainty on the properties of structure can be reasonably predicted by using the dynamic analysis than by using lateral force procedure. 2) The mode coupled by translation and torsion induced the overturning moments not only in the direction of excitations but also in the perpendicular direction: The axial forces in columns due to this transverse overturning moment cannot be adequately predicted using the existing mode analysis technique, and 3) the hysteretic curve and the strength diagram between base shear and torque(BST) clearly reveal the predominant mode of vibrations and the failure mode.

Modelling damage potential of high‐frequency ground motions

AbstractDamage to building structures due to underground blast‐induced ground motions is a primary concern in the corresponding determination of the safe inhabited building distance (IBD). Because of the high‐frequency nature of this category of ground motions and especially the presence of significant vertical component, the characteristics of structural response and damage differ from those under seismic type low‐frequency ground motions. This paper presents a numerical investigation aimed at evaluating reinforced concrete (RC) structure damage generated by underground blast‐induced ground excitation. In the numerical model, two damage indices are proposed to model reinforced concrete failure. A fracture indicator is defined to track the cracking status of concrete from micro‐ to macrolevel; the development of a plastic hinge due to reinforcement yielding is monitored by a plastic indicator; while the global damage of the entire structure is correlated to structural stiffness degradation represented by its natural frequency reduction. The proposed damage indices are calibrated by a shaking table test on a 1: 5‐scale frame model. They are then applied to analyse the structural damage to typical low‐ to high‐rise RC frames under blast‐induced ground motions. Results demonstrate a distinctive pattern of structural damage and it is shown that the conventional damage assessment methods adopted in seismic analysis are not applicable here. It is also found that the existing code regulation on allowable peak particle velocity of blast‐induced ground motions concerning major structural damage is very conservative for modern RC structures. Copyright © 2003 John Wiley & Sons, Ltd.

高層鉄筋コンクリート造の現状

高層鉄筋コンクリート造の現状

軟弱地盤に立つ変断面超高RC煙突の設計と施工

軟弱地盤に立つ変断面超高RC煙突の設計と施工

高性能AE減水剤を用いた超高層RC住宅の設計と施工

高性能AE減水剤を用いた超高層RC住宅の設計と施工

高層鉄筋コンクリート建物の現状と今後の問題点

最近数年間, 大手建設会社を中心としてブームになってきた 25～30 階の鉄筋コンクリートラーメン構造の集合住宅建築について, 平面・立面の構造計画, 主要構造部材の断面構成, 使用材料, プレキャストコンクリート工法・鉄筋の先組み工法, 鉄筋継手などの工法計画, 耐震設計の基本方針, 目標耐震性能, 設計用地震力・崩壊メカニズムの選定とその確保のための設計手法, 実験による確認, 質点系および骨組の非線形地震応答解析などの傾向を述べ, 今後の問題点を指摘したものである。

鉄筋コンクリート超高層建築物の研究 : 人工軽量骨材を用いた SRC フレーム及び筋かい入り耐震壁の実験

鉄筋コンクリート超高層建築物の研究 : 人工軽量骨材を用いた SRC フレーム及び筋かい入り耐震壁の実験