蔡克銓Tsai, Keh-Chyuan臺灣大學:土木工程學研究所吳克強Wu, Ke-ChiangKe-ChiangWu2010-06-302018-07-092010-06-302018-07-092009U0001-3007200915155500http://ntur.lib.ntu.edu.tw//handle/246246/187704近年來恐怖攻擊事件在世界各地造成無數傷亡，其中以自殺炸彈客類型的恐怖攻擊事件最難預防，因為這類型的攻擊炸彈可以輕易的藉由背包運送且安置在任何角落，尤其對於柱子所造成的破壞有可能導致漸進式倒塌的風險。背包炸彈通常不會有太大量的炸藥，範圍大約是5公斤至25公斤，但安放的位置恰當卻對結構有莫大的威脅。 在本研究中，使用有限元素分析軟體LS-DYNA來得到柱子受炸彈攻擊時之動態反應以及其殘餘軸向強度，此外有三根柱子試體在野外做接觸爆炸試驗，分別為一根鋼骨鋼筋混凝土柱及兩根鋼筋混凝土柱，接觸爆炸試驗結果將與有限元素分析結果比較驗證模型的準確性。應變速率對於分析模型的準確性有重要影響，動態增量因子被用來描述此現象。建立三根試體之有限元素模型，其分析結果與接觸爆炸試驗結果有相似的破壞輪廓。 利用驗證過的有限元素分析模型做參數研究，分析柱子殘餘軸向強度與材料強度、斷面細節以及爆炸條件的關係，參數研究對象包含鋼骨鋼筋混凝土柱及鋼筋混凝土柱，爆炸條件為TNT炸藥作用在柱子底部或柱子高度1.5米處，炸藥用量為2.5公斤至25公斤。 藉由對不同參數的回歸分析提出四組分析公式可用來預測柱子軸向殘餘強度，根據所提出公式得到的柱子軸向殘餘強度可以與軸向工作載重相比較，若軸向工作載重大於軸向殘餘強度，則結構物有破壞甚至倒塌的風險。The risks represented by suitcase bombs are of particular concern in the modern context because they can be transported by hand and placed almost anywhere in close proximity with key structural components. Although suitcase bombs are relatively small in size, ranging from to , their effect on structural components may be severe. The most common failure mode of blast loads is progressive collapse. As such, one of the most useful information that can aid in assessing if a structure would collapse is the residual axial strength of its columns. In this study, a high-fidelity physics based computer program, LS-DYNA is utilized to provide numerical simulations of the dynamic response and residual axial strength. There are three column specimens experimented with contact explosive tests out in the field, one being a composite steel-concrete column and the other two being reinforced concrete columns. The analytical results were compared with the test results for validation. The strain rate effects are important to the accuracy of simulations. The dynamic increase factor is used to describe this phenomenon. The models based on these three column specimens produced similar damage profiles when subjected to blast loads as applied to the actual specimens during the blast tests conducted in the field. An extensive parametric study utilized the validated finite element models to investigate the relationship with residual axial strength and other parameters, such as material strength, column details and blast conditions. Two types of columns were considered in the parametric study. One is the reinforced concrete column and the other is the composite steel-concrete column. TNT explosive, of weight between and , was used and located at either the bottom of columns or a height of from the footing of columns. Four analytical formulae were derived through multivariable regression analysis in terms of various parameters to predict the residual capacity index based on the non-dimensional column dimension parameter. According to the proposed formulae, the residual capacity index can be determined and compared with service axial load index. In general, a larger value of residual capacity index indicates a greater column resistance to the blast loads. A column whose service axial load index is greater than its residual capacity index is said to have failed or collapsed. Otherwise, the column has sufficient strength for the threat considered.口試委員會審定書 iCKNOWLEDGEMENTS ii 要 iiiBSTRACT ivABLE OF CONTENTS viIST OF FIGURES xIST OF TABLES xxivHAPTER 1 INTRODUCTION 1HAPTER 2 ANALYTICAL METHODS FOR BLAST-RESISTANT DESIGN 3.1 Blast load 3.1.1 Blast wave phenomena 3.1.2 Blast wave configuration 4.1.3 TNT equivalence 6.1.4 The blast scaling law 6.1.5 Prediction of blast pressure and impulse 7.2 Structural response to blast load 8.2.1 Single-degree-of-freedom system 8.2.2 Reinforced concrete frame structure 12.3 Column response to blast load 14HAPTER 3 LS-DYNA ANALYSIS OF COLUMN DAMAGES UNDER THE BLAST LOADS 16.1 Introduction of LS-DYNA 16.2 Analytical model 16.2.1 Structural geometry 16.2.1.1 Solid element for concrete and structural steel 17.2.1.2 Beam element for steel reinforcing bar 21.2.1.3 Interaction between steel and concrete element 25.2.1.4 Boundary conditions 26.2.2 Material model 27.2.2.1 Concrete material model 27.2.2.1.1 Concrete strength envelope 28.2.2.1.2 The compaction model for concrete 34.2.2.1.3 Strain rate effect for concrete 36.2.2.1.4 Concrete erosion 40.2.2.2 Steel material model 40.2.3 Simulation of blast loads used in hydrocodes 43.3 Analytical procedure 44HAPTER 4 VALIDATION OF ANALYTICAL RESULTS 47.1 Explosive test on columns 47.1.1 Experiment specimens 47.1.1.1 Column specimen details 47.1.1.1.1 RC column specimen details 47.1.1.1.2 Composite steel-concrete column specimen details 48.1.1.2 Column specimen materials 49.1.2 Test setup 50.1.3 Test results 51.2 Comparisons between analytical and test results 54.2.1 Composite steel-concrete column specimen results 54.2.2 RC column specimen 1 results 55.2.3 RC column specimen 2 results 56HAPTER 5 NUMERICAL SIMULATION STUDY OF RC COLUMNS 58.1 Numerical simulation matrix 58.2 Numerical results of RC columns in blast stage 61.2.1 Effect of column depth 61.2.2 Effect of column height 67.2.3 Effect of explosive location 68.2.4 Effect of axial load ratio 71.2.5 Effect of transverse reinforcement ratio 73.2.6 Effect of longitudinal reinforcement ratio 75.3 Numerical results of residual capacity index of the blast-damaged RC columns 77.3.1 Effect of column depth 78.3.2 Effect of column height 83.3.3 Effect of explosive location 84.3.4 Effect of axial load ratio 86.3.5 Effect of transverse reinforcement ratio 88.3.6 Effect of longitudinal reinforcement ratio 89.4 Proposed formulae for determining the residual capacity index of blast-damaged RC columns 92HAPTER 6 NUMERICAL SIMULATION STUDY OF COMPOSITE STEEL-CONCRETE COLUMNS 96.1 Numerical simulation matrix 96.2 Numerical results of composite steel-concrete columns in blast stage 98.2.1 Effect of column depth 98.2.2 Effect of column height 103.2.3 Effect of explosive location 104.2.4 Effect of axial load ratio 108.2.5 Effect of structural steel 111.3 Numerical results of residual capacity index of the blast-damaged composite steel-concrete columns 115.3.1 Effect of column depth 116.3.2 Effect of column height 120.3.3 Effect of explosive location 122.3.4 Effect of axial load ratio 126.3.5 Effect of structural steel 128.4 Proposed formulae for determining the residual capacity index of blast-damaged composite steel-concrete columns 132HAPTER 7 CONCLUSIONS AND RECOMMENDATIONS 137.1 Conclusions 137.2 Recommendations 140EFERENCES 142PPENDIX A EXPERIMENT SPECIMENS 145PPENDIX B NUMERICAL SIMULATION DATA OF RC COLUMNS 151PPENDIX C NUMERICAL SIMULATION DATA OF COMPOSITE STEEL-CONCRETE COLUMNS 1604459641 bytesapplication/pdfen-USLS-DYNA接觸爆炸試驗鋼筋混凝土柱鋼骨鋼筋混凝土柱分析公式軸向殘餘強度contact explosive testreinforced concrete columncomposite steel-concrete columnanalytical formulaeresidual capacity indexthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/187704/1/ntu-98-R96521208-1.pdf