Advanced Multi-Mechanism Investigation of Thin UHPC Cladding Panels with Embedded Anchorage Systems through Experimental and Numerical Approaches

다국어 초록 (Multilingual Abstract)

Thin ultra-high-performance concrete （UHPC） panels have recently attracted considerable attention for lightweight exterior cladding systems due to their high strength, durability, and architectural versatility. However, the structural safety of such systems strongly depends on the connection performance between UHPC panels and supporting structures. Although embedded anchors are widely used in practical applications, their structural behavior and governing strength parameters in thin UHPC panels under shallow embedment conditions remain insufficiently understood.

This study investigates the structural performance of thin UHPC cladding panels and embedded anchorage systems through an integrated experimental, numerical, and data-driven framework. The experimental program includes the evaluation of UHPC material properties, out-of-plane flexural behavior of thin panels, in-plane cyclic shear behavior, wind-induced fatigue performance, and the pull-out and shear capacities of embedded anchors. The results demonstrated that the developed UHPC achieved compressive strengths exceeding 150 MPa and flexural strengths greater than 24 MPa, providing high strength, stable structural performance, and effective crack control suitable for lightweight facade applications. Steel fiber-reinforced UHPC exhibited higher compressive strength and stiffness, whereas PE fiber-reinforced UHPC showed superior ductility and crack control. In addition, steel strip retrofitting significantly improved the flexural strength and deformation capacity of large-scale UHPC panels.

The proposed bottom-extension anchorage system demonstrated stable structural behavior under extremely shallow embedment conditions in thin UHPC panels. The anchorage performance was primarily governed by geometric parameters, particularly embedment depth and anchor base diameter. Increasing embedment depth significantly improved the pull-out capacity, while the dominant failure mode was characterized by concrete breakout. Furthermore, cyclic fatigue tests under wind-type loading confirmed the excellent durability of thin UHPC panels, which sustained repeated loading cycles without visible damage.

Finite element simulations developed in LS-DYNA successfully reproduced the experimentally observed load–displacement responses, crack propagation, and failure mechanisms, showing good agreement with the test results. In addition, a machine learning-based Gaussian Process Regression （GPR） framework was developed using combined experimental and numerical datasets to predict the pull-out and shear strengths of embedded anchors. The developed models demonstrated reliable predictive capability and stable generalization performance under various anchorage configurations.

The findings of this study provide valuable insight into the structural behavior of thin UHPC panels and embedded anchorage systems and confirm their feasibility for lightweight, high-performance facade applications. Furthermore, the proposed integrated framework combining experiments, numerical simulations, and machine learning provides a reliable basis for the future design and optimization of anchorage systems in thin UHPC structures.

목차 (Table of Contents)

• 1 INTRODUCTION . 1
• 1.1 Overview . 1
• 1.2 Research motivation and contributions 6
• 1.3 Organization of the thesis . 7
• 1.4 Publications . 9
• 2 RESEARCH CONCEPT AND METHODOLOGY 12
• 2.1 Research concept 12
• 2.2 Research methodology 14
• 3 IN-PLANE AND OUT-OF-PLANE BEHAVIOR OF THIN UHPC PANELS 17
• 3.1 Introduction . 17
• 3.2 Mechanical strength testing of UHPC materials 20
• 3.2.1 Fiber properties and specimen parameters . 20
• 3.2.2 Testing results of UHPC materials . 22
• 3.3 Testing strength of UHPC panel . 25
• 3.3.1 Summary of UHPC panel specimens . 25
• 3.3.2 Out-of-plane flexural testing of UHPC panel specimens . 27
• 3.3.3 In-plane shear test of UHPC panel specimens 35
• 3.4 Calculation of the maximum flexural strength of specimens . 40
• 3.4.1 The unretrofitted UHPC panel 40
• 3.4.2 The retrofitted UHPC panels 42
• 3.5 Numerical simulation model of specimens . 45
• 3.5.1 Overview of numerical simulation model 45
• 3.5.2 Numerical simulation procedure 48
• 3.5.3 Numerical simulation results 50
• 3.6 Conclusion 53
• 4 FATIGUE PERFORMANCE OF COMPOSITE UHPC PANELS UNDER WIND LOADING . 56
• 4.1 Introduction . 56
• 4.2 Experimental program of fatigue wind loading 58
• 4.2.1 Material properties 58
• 4.2.2 Summary of specimens . 60
• 4.2.3 Casting process of specimens . 61
• 4.2.4 Test setup of specimen . 63
• 4.2.5 Probabilistic wind load acting on the UHPC panel 65
• 4.2.6 Testing results and discussions . 69
• 4.3 Conclusion 84
• 5 PULL-OUT BEHAVIOR OF CAST-IN EXPANSION ANCHORS IN THIN UHPC PANELS 86
• 5.1 Introduction . 86
• 5.2 Pull-out test of anchor embedded in UHPC panel 90
• 5.2.1 Mechanical strength of UHPC 90
• 5.2.2 Parameters of specimens 91
• 5.2.3 Pull-out test setup . 92
• 5.2.4 Testing results . 94
• 5.3 Validation of the testing results by numerical simulation 98
• 5.3.1 Introduction to numerical material models . 98
• 5.3.2 Numerical simulation model process . 102
• 5.3.3 Simulation results and discussion . 103
• 5.3.4 Parametric study by numerical simulation models . 108
• 5.4 Proposed equation for pull-out capacity of expanded-base anchors 114
• 5.5 Conclusion 121
• 6 SHEAR BEHAVIOR OF CAST-IN EXPANSION ANCHORS IN THIN UHPC PANELS . 123
• 6.1 Introduction . 123
• 6.2 Specimen preparation . 126
• 6.2.1 Detail dimension of specimens . 126
• 6.2.2 Casting specimen procedure . 127
• 6.3 Shear tests of anchor specimens . 129
• 6.3.1 Test setup of specimens 129
• 6.3.2 Testing results and discussion 130
• 6.4 Numerical simulation modeling of specimens . 135
• 6.4.1 Overview 135
• 6.4.2 Numerical simulation procedure 136
• 6.4.3 Comparison of the simulation and testing results . 139
• 6.5 Predict the shear strength of anchor embedded in concrete 145
• 6.6 Parametric study based on finite element simulations 150
• 6.6.1 Investigation of the influence of anchor bottom diameter 150
• 6.6.2 Investigation of the influence of embedded depth 152
• 6.6.3 Investigation of the influence of both anchor bottom diameter and embedded depth . 153
• 6.7 Conclusion 155
• 7 MACHINE LEARNING–DRIVEN PREDICTION OF ANCHOR PULL- OUT AND SHEAR STRENGTH IN THIN UHPC PANELS USING GAUSSIAN PROCESS REGRESSION 158
• 7.1 Introduction . 158
• 7.2 Research objectives 160
• 7.3 Experimental program of anchor specimens 162
• 7.3.1 Test setup 162
• 7.3.2 Test results 163
• 7.4 Numerical simulation of anchor specimens 164
• 7.4.1 Numerical simulation procedure 164
• 7.4.2 Numerical simulation results 166
• 7.5 Machine Learning–Based Strength Prediction . 167
• 7.5.1 Gaussian Process regression . 167
• 7.5.2 Generating data . 172
• 7.5.3 Prediction results of machine learning approach 175
• 7.6 Conclusion 181
• 8 CONCLUSIONS AND FUTURE RESEARCH . 183
• 8.1 Conclusions . 183
• 8.2 Future research 186
• REFERENCES . 188