Seismic Evaluation and Floor Response Spectrum Analysis of Elevated Water Tanks with Height-Adjustable Steel Supports = 층응답스펙트럼 예측 회귀식 개발 및 높이조절형 강재 물탱크 받침대 내진평가

국문 초록 (Abstract)

본 논문은 반복적인 비선형 시간이력해석 없이도 바닥응답스펙트럼을 생성하고 조절식 강재 물탱크 받침대를 설계·규제할 수 있는 예측 등급의 프레임워크를 제안한다. 제안된 방법은 회귀 보정 모달 중첩 바닥응답스펙트럼(Regression Corrected Modal Superposition Floor Response Spectrum, RCMS-FRS)으로 명명되며, 모드형상, 참여계수, 고유주기, 감쇠비 등 모달 정보만을 이용해 층별 스펙트럴 요구도를 합성한다. 이 방법은 단순한 사후 처리(post-processing)가 아니라 설계 적용을 목적으로 하므로, 모든 단계에서 물리적 의미가 추적 가능하도록 구성되었다.

핵심 요소는 선형 모달 추정치와 상세 해석에서 관찰되는 요구도를 일치시키는 높이 의존 비탄성 보정계수 Rμ이다. 단주기 평탄부를 포함하는 4구간 스펙트럼 형식은 증폭 구간에서 감쇠 구간으로의 전이를 매끄럽게 하면서도 구조 동역학적 특성을 충실히 반영한다. 본 방법은 대표 건물(archetype buildings)과 실물 크기의 높이 조절식 받침대를 대상으로 보정되었으며, 푸시오버 시험과 상세 유한요소해석을 통해 검증되었다. 받침대에 대해서는 국부 응답 메커니즘을 포착하고 실험 관찰 결과와의 일관성을 확인하기 위해 ANSYS를 이용한 비선형 유한요소모델을 구축하여 해석을 수행하였다.

본 논문에서 개발된 설계 보조 차트는 시공 의사결정을 동적 응답과 직접적으로 연결한다. 요구–내력 경로(demand–capacity pathway)는 층별 요구가 개별 부재로 전달되는 과정을 추적하고, 지배적인 한계상태가 볼트 미끄러짐, 앵커 인장, 앵커 전단임을 식별하며, 보 웹 전단은 지배적이지 않음을 확인한다. 제안된 작업 흐름은 반복적인 해석과 설계 반복을 줄이면서도 최소 기준을 넘어서는 내진 적합성 평가를 지원하며, 다른 비구조 시스템으로도 용이하게 확장될 수 있다.

다국어 초록 (Multilingual Abstract)

This thesis proposes a prediction-grade framework for generating floor response spectra and regulating adjustable steel water tank supports without exhaustive nonlinear time-history analysis. The method, named Regression Corrected Modal Superposition Floor Response Spectrum (RCMS-FRS), synthesizes floor-wise spectral demand from modal data only, including mode shapes, participation factors, periods, and damping. It is intended for design, not merely post-processing, so every step preserves traceable physical meaning.

At the core is a height-dependent inelastic correction Rμ that reconciles linear modal estimates with demands observed in detailed analyses. A four-zone spectrum with a short-period plateau secures a smooth transition from amplification to decay while remaining faithful to structural dynamics. The method is calibrated using archetype buildings and a full-scale height-adjustable support frame, verified through pushover tests and detailed finite-element analyses. For the support frame, nonlinear finite-element models were developed and analyzed in ANSYS to capture local response mechanisms and to confirm consistency with experimental observations.
A design aid chart developed in this thesis links construction decision directly to dynamic response. A demand-capacity pathway traces the transfer of floor demand to individual components and identifies the governing limit states as bolt slip, anchor tension, and anchor shear, with beam-web shear remaining non-controlling. The proposed workflow supports seismic qualification beyond minimum code requirements while reducing repeated analysis and iteration, and it can be readily extended to other nonstructural systems.

목차 (Table of Contents)

• Abstract i
• List of Tables vi
• List of Figures vii
• Chapter 1. Introduction 1
• 1.1 Motivation of Research 1
• 1.2 Objectives and Scope 2
• 1.3 Organization 3
• Chapter 2. Literature Review 5
• 2.1 Water Tank Support 5
• 2.1.1 Function of water tanks 5
• 2.1.2 Structure of water tanks 6
• 2.1.3 Failure mode of water tanks 7
• 2.1.4 Importance of dry type support 9
• 2.2 Current Seismic Design Standard for NSC 10
• 2.3 Research on Seismic Design of NSC 15
• 2.3.1 Advances in dynamic analysis methods 15
• 2.3.2 Classical studies on FRS 16
• 2.3.3 Contemporary studies on FRS 19
• 2.3.4 Summary of limitations in FRS approaches 22
• Chapter 3. Development of FRS Method 25
• 3.1 Necessity for Seismic Design of NSC 25
• 3.2 Definition and Purpose of FRS 25
• 3.3 Limitations of Existing FRS Estimation Methods 26
• 3.3.1 Empirical FRS methods 26
• 3.3.2 SDOF based FRS methods 26
• 3.3.3 MDOF based FRS methods 27
• 3.3.4 Limitations of existing FRS approaches 27
• 3.4 RCMS-FRS: Proposed Method 29
• 3.4.1 Overview of RCMS procedure 29
• 3.4.2 Preprocessing 30
• 3.4.3 Seismic input and analysis procedure 32
• 3.4.4 Building derivation of RCMS-FRS 33
• 3.5 Advantages and Applications 47
• 3.5.1 Reliability relative to prior studies 47
• 3.5.2 Validity across diverse plan aspect ratios 49
• 3.6 Summary 54
• Chapter 4. Experimental Validation of Height-Adjustable Steel Supports 55
• 4.1 Height-adjustable Steel Support 55
• 4.1.1 Overview of dry type support 55
• 4.1.2 Details of dry type support 57
• 4.2 Objectives and Scope 58
• 4.3 Material Tests 61
• 4.4 Structural Tests 63
• 4.5 Experimental Results 67
• 4.6 Structural Evaluation 69
• 4.6.1 Function of water tanks 70
• 4.6.2 Structure of water tanks 71
• 4.7 Optimal Layout 73
• 4.7.1 Estimation of equivalent static loads 73
• 4.7.2 Member force comparison 75
• 4.8 Strength and Structural Safety Assessment 77
• 4.9 FEA Verification 79
• 4.9.1 Purpose and overview 79
• 4.9.2 Geometric modeling and components 79
• 4.9.3 Analytical results 83
• 4.10 Summary 87
• Chapter 5. Development of Design Aid Charts 89
• 5.1 Overview of Specification Development 89
• 5.2 Analyses and Results 91
• 5.3 Summary 94
• Chapter 6. Conclusion 95
• References 97
• 국 문 초 록 100