Novel Active Wind Tunnel Testing System and Analysis of Building Interference Effect = 액티브 풍동실험 장비 개발과 이를 활용한 빌딩 간섭 효과 연구

다국어 초록 (Multilingual Abstract)

This study developed a novel active wind tunnel system capable of reproducing realistic atmospheric boundary layer characteristics within a short test section and experimentally investigated the aerodynamic interference effects acting on high-rise buildings. Prior to experimentation, the theoretical requirements for boundary layer wind tunnel (BLWT) test and the similarity conditions prescribed in design codes and standards were reviewed. This review confirmed that both geometric and kinematic similarities must be satisfied to simulate wind loads on high-rise buildings accurately. To overcome the limitations inherent in conventional passive turbulence generation methods, an active wing control system was developed, which successfully reproduced desired turbulence characteristics within the test section. Based on this turbulence generator, an active wind tunnel system was constructed. Its performance was validated by comparing experimental results obtained from active wind tunnel tests with those from tests using conventional large-scale wind tunnels conducted on identical building models.
Using the developed active wind tunnel, a total of 4,212 tests were conducted under varying interference building heights, locations, and wind directions, enabling a quantitative evaluation of interference effects in the presence of two neighboring buildings. The results revealed that the presence of interference buildings significantly affects not only the mean wind loads but also the fluctuating components and spectral characteristics of wind forces. In particular, in addition to shielding effects, it was confirmed that aerodynamic wind loads can be substantially amplified due to vortices shed from the interference buildings. It was also observed that across-wind and torsional wind loads, both of which are governed by fluctuating components rather than mean component, can experience considerable amplification. Specifically, the interference factor (IF) for the base torsional moment reached up to 4.03, indicating the potential for dramatic increases in dynamic structural responses due to the aerodynamic interference effect.
These findings highlight the importance of incorporating interference effects into the preliminary design stage, especially in urban environments where multiple neighboring buildings are present. This underscores the need for simplified design methodologies that can account for such effects. As a foundational step toward this purpose, this study proposed a set of wind force PSD models corresponding to various interference building locations and relative heights of interference building. These models are expected to allow for the indirect incorporation of interference effects into wind design for the structure. The experimental data and PSD models presented herein may serve as fundamental resources for performance-based wind design of high-rise buildings.

국문 초록 (Abstract)

본 연구에서는 짧은 시험 구간에서도 실제 대기 경계층 특성을 모사할 수 있는 능동형 풍동 시스템을 개발하고, 이를 활용하여 고층 건물에 작용하는 공기역학적 간섭 효과를 실험적으로 분석하였다. 실험에 앞서, 경계층 풍동(BLWT) 실험의 이론적 요구사항과 국내외 설계 기준에 따른 유사 조건을 검토하였다. 이를 통해 고층 건물 풍하중 모사를 위해서는 기하학적 및 운동학적 상사가 필수적임을 확인하였다. 기존의 수동적인 난류 생성 방식이 가진 한계를 극복하고자 능동 제어 방식의 윙 제어 시스템을 개발하였고, 이 시스템을 통해 시험 구간 내에서 목표 난류 특성을 성공적으로 재현하였다. 개발된 난류생성장치를 활용하여 능동제어 풍동실험 설비를 구축하였으며, 동일한 실험 모형으로 대형 풍동에서 수행한 기존 실험 데이터와 비교하여 구축된 능동제어 풍동의 유효성을 검증하였다.
개발된 능동제어 풍동을 활용하여 간섭건물의 상대 높이, 위치, 그리고 풍향을 달리한 총 4,212개의 시험을 수행하였으며, 이를 통해 두 개의 간섭건물이 존재할 때 발생하는 간섭 효과를 정량적으로 평가하였다. 실험 결과, 간섭건물의 존재는 평균 풍하중뿐만 아니라 변동 성분과 풍력 스펙트럼 특성에도 중대한 영향을 미치는 것으로 나타났다. 특히, 간섭건물에 의한 차폐 효과 외에도 간섭건물에서 박리된 와류의 영향으로 공기역학적 풍하중이 크게 증가할 수 있음이 확인되었다. 평균 성분에 비해 변동 성분의 비중이 큰 풍직각 방향 풍하중과 비틀림 풍하중이 크게 증폭될 수 있으며, 비틀림 풍하중의 밑면 모멘트에 대한 간섭계수(Interference Factor, IF)는 최대 4.03에 달해 간섭으로 인한 구조물의 동적 응답이 극대화될 수 있음을 확인하였다.
이러한 결과는 다수의 간섭건물이 존재할 경우 설계 초기 단계에서 간섭 효과를 반영한 사전 검토의 필요성을 시사하며, 간섭 효과를 반영할 수 있는 간소화된 설계 방법이 필요할 것으로 판단된다. 본 연구에서는 이를 위한 기초 작업으로 다양한 간섭 위치와 간섭건물 높이에 대한 풍력 PSD 모델을 제시하였으며, 이를 통해 간접적으로 간섭 효과를 반영할 수 있을 것으로 기대한다. 본 연구에서 제시한 실험 데이터와 PSD 모델은 고층 건물의 성능기반 내풍 설계를 위한 기초 자료로 활용될 수 있을 것이다.

목차 (Table of Contents)

• Chapter 1. Introduction 1
• 1.1 Wind and Its Effects on Structures 1
• 1.2 Wind Design of Structures and Wind Tunnel Test 5
• 1.3 Interference Effects 11
• 1.4 Performance-Based Wind Design 17
• 1.5 Research Objectives and Scopes 24
• 1.6 Outline of Dissertation 25
• Chapter 2. Review on Wind Tunnel Test and Interference Effect 27
• 2.1 History of Wind Tunnel 28
• 2.2 Requirement for Boundary Layer Wind Tunnel 31
• 2.3 Wind Tunnel with Short Test Section 38
• 2.4 Interference Effects by Neighboring Buildings 44
• 2.5 Summary 51
• Chapter 3. Development of Active Wind Tunnel Testing System 53
• 3.1 Code Provision Related to Wind Tunnel Test 54
• 3.2 Development of Active Wind Tunnel Testing System 57
• 3.2.1 Motivation of development 57
• 3.2.2 Construction of wind tunnel with short test section 59
• 3.2.3 Simulation of wind flow using short test section 63
• 3.2.4 Turbulence generator using active fan control 75
• 3.2.5 Turbulence generator using active wing control 92
• 3.2.6 Comparison between two turbulence generators 107
• 3.3 Verification of Active Wind Tunnel Testing System 109
• 3.3.1 Wind tunnel test data from conventional wind tunnel 109
• 3.3.2 Open-source wind tunnel test database 114
• 3.3.3 Correction of distortion by tubing system 116
• 3.3.4 Wind tunnel test result 122
• 3.3.5 Comparison of wind tunnel test result 149
• 3.4 Summary 151
• Chapter 4. Wind Tunnel Test Considering Interference Effect 155
• 4.1 Review on Interference Effects 156
• 4.1.1 Flow patterns around isolated building 156
• 4.1.2 Interference effects due to surrounding buildings 159
• 4.1.3 Summary and research needs 161
• 4.2 Experimental Program 163
• 4.2.1 High-frequency pressure integration (HFPI) test 164
• 4.2.2 Test model 165
• 4.2.3 Test setup 170
• 4.3 Test Results and Discussion 174
• 4.3.1 Aerodynamic wind force coefficient 176
• 4.3.2 Skewness 214
• 4.3.3 Kurtosis 232
• 4.4 Summary 250
• Chapter 5. Quantitative Evaluation of Aerodynamic Loads and Resonant Responses 255
• 5.1 Quantitative Evaluation of Interference Effects 256
• 5.2 Peak Reduced Frequency 271
• 5.2.1 Parallel layout 273
• 5.2.2 Tandem layout 277
• 5.2.3 High interference factor (IF) locations 280
• 5.3 Vertical Distribution of Local Wind Force Coefficient 288
• 5.3.1 Parallel layout 289
• 5.3.2 Tandem layout 295
• 5.3.3 High IF locations 302
• 5.4 Vertical Distribution of Peak Reduced Frequency 310
• 5.5 Power Spectral Density Model of Wind Force 326
• 5.5.1 Review of current PSD models 326
• 5.5.2 Second-order system model 328
• 5.5.3 Curve fitting 331
• 5.5.4 Background component 335
• 5.5.5 Vortex-induced component 347
• 5.5.6 Reconstruction of interfered wind load PSD 358
• 5.6 Calculation of Resonance Component 359
• 5.6.1 Equivalent single degree of freedom (SDOF) analysis 359
• 5.6.2 Assumptions for ESDOF model 360
• 5.6.3 Elastic response of ESDOF for isolated case 364
• 5.6.4 Change in resonance force by interference effect 367
• 5.7 Summary 376
• Chapter 6. Conclusions and Recommendations 381
• 6.1 Summary and Conclusions 381
• 6.2 Recommendations and Future Works 385
• References 387
• Appendix A 399
• Appendix B 405
• Appendix C 419
• Appendix D 421
• Appendix E 429
• Appendix F 479
• 국 문 초 록 487
• Acknowledgement 489