Tesi - Seismic analysis and design of reinforcements for the church of Zuidwolde, Groningen, The Netherlands

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3.2 The software 3muri . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

3.2.1 Theory above the software . . . . . . . . . . . . . . . . . . . . . . . . 34

3.2.2 The masonry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

3.2.3 The role of the walls and the equivalent frame approach . . . . . . . 35

3.2.4 The role of the connections . . . . . . . . . . . . . . . . . . . . . . . 36

3.2.5 The role of roofs, floors and vaults . . . . . . . . . . . . . . . . . . . 38

3.2.6 The macro-elements . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

3.3 Building the model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

3.3.1 Define the wall geometry of the buildings . . . . . . . . . . . . . . . 39

3.3.2 Define the height of the floors . . . . . . . . . . . . . . . . . . . . . . 40

3.3.3 Define the geometry of floors, roofs and vaults . . . . . . . . . . . . 41

3.3.4 A studio of the wooden trusses of the church roof . . . . . . . . . . . 43

3.3.5 Assign the loads to each element . . . . . . . . . . . . . . . . . . . . 46

3.3.6 Define the materials properties . . . . . . . . . . . . . . . . . . . . . 46

3.4 Characteristics of the masonry as building material . . . . . . . . . . . . . . 47

3.4.1 Examples of test on the masonry . . . . . . . . . . . . . . . . . . . . 50

4 Solution obtained with the software and comparison with the existing

cracks 52

4.1 The final model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

4.2 The procedure to obtain the results with 3Muri . . . . . . . . . . . . . . . . 53

4.2.1 Generate a mesh with the software . . . . . . . . . . . . . . . . . . . 54

4.2.2 Assign the ground motion parameters . . . . . . . . . . . . . . . . . 54

4.3 The results of the analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

4.3.1 Pushover analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

4.3.2 Analysis performed . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

4.3.3 The most severe results for the Y direction . . . . . . . . . . . . . . 60

4.3.4 The most severe results for the X direction . . . . . . . . . . . . . . 61

4.3.5 Understanding the driving force: a simple exercise . . . . . . . . . . 62

4.3.6 Check the results between a ”hand calculation” . . . . . . . . . . . . 64

4.4 Comparison with the existing cracks . . . . . . . . . . . . . . . . . . . . . . 66

4.5 Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

5 Analysis of local failure mechanisms 68

5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

5.2 Theoretical approach, Linear kinematics analysis . . . . . . . . . . . . . . . 69

5.3 Reading the mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

5.4 The mechanisms read for the case of Zuidwolde . . . . . . . . . . . . . . . . 71

Contents vii

5.5 Procedure to follow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

5.5.1 Step1: Identifying the static scheme . . . . . . . . . . . . . . . . . . 73

5.5.2 Step2: Evaluating the forces using the software SAP2000 . . . . . . 74

5.5.3 Step3: Validate the results trough a manual calculation . . . . . . . 80

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5.5.4 Step4: Calculation trough the software 3Muri . . . . . . . . . . . . 83

5.5.4.1 Mechanism 1: Overturning of the façade due to the push of

the trusses of the roof . . . . . . . . . . . . . . . . . . . . . 84

5.5.4.2 Mechanism 2: The tower bell . . . . . . . . . . . . . . . . . 86

5.6 Some comments about the results . . . . . . . . . . . . . . . . . . . . . . . . 86

6 Proposal of reinforcements for the case of Zuidwolde 88

6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

6.2 Main problems of the building . . . . . . . . . . . . . . . . . . . . . . . . . . 88

6.2.1 The damage to the main body of the church . . . . . . . . . . . . . . 89

6.2.2 The tower of the church . . . . . . . . . . . . . . . . . . . . . . . . . 89

6.3 Possible solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

6.3.1 Wooden floor with an armoured concrete slab . . . . . . . . . . . . . 90

6.3.2 Wooden floor with diagonal steel profiles . . . . . . . . . . . . . . . 90

6.3.3 Wooden floor with fibre reinforced polymer ”FRP” . . . . . . . . . . 91

6.4 Design of a solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

6.5 Results obtained with the software . . . . . . . . . . . . . . . . . . . . . . . 92

6.5.1 The new concrete slab . . . . . . . . . . . . . . . . . . . . . . . . . . 93

6.5.2 The most severe results for the Y direction . . . . . . . . . . . . . . 94

6.5.3 The most severe results for the X direction . . . . . . . . . . . . . . 95

6.6 Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

7 Conclusions 97

7.1 General comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

7.2 Main conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

A A study of the masonry and of the existing cracks 99

B Evaluation of the quality of the masonry 100

C A study of the wooden trusses of the roof of the church of Zuidwolde 101

Bibliography 102

List of Figures

1.1 Map of the gas and oil fields in the Netherlands. . . . . . . . . . . . . . . . 1

1.2 Annual rate of extraction in Groningen area. . . . . . . . . . . . . . . . . . 2

1.3 Damage to the internal walls of a Groningen farmhouse. . . . . . . . . . . . 3

1.4 Main driver: reservoir compaction due to pressure reduction. . . . . . . . . 5

1.5 Fault Mechanism of compaction. . . . . . . . . . . . . . . . . . . . . . . . . 5

1.6 Sesimic intensity for the area of Groningen. . . . . . . . . . . . . . . . . . . 7

1.7 Ground motion parameters for the area of Groningen. . . . . . . . . . . . . 7

1.8 Final PGA Contours set by KNMI. . . . . . . . . . . . . . . . . . . . . . . . 9

2.1 Geolocation of the town of Zuidwolde. . . . . . . . . . . . . . . . . . . . . . 12

2.2 View of the area around the church. . . . . . . . . . . . . . . . . . . . . . . 13

2.3 Condition of the church before the restoration of 1998. . . . . . . . . . . . . 15

2.4 Examples of cracks in the windows. . . . . . . . . . . . . . . . . . . . . . . . 16

2.5 Examples of cracks in the whole building. . . . . . . . . . . . . . . . . . . . 17

2.6 The actual response spectrum. . . . . . . . . . . . . . . . . . . . . . . . . . 18

2.7 Possible different mechanisms individuated for wall and façades. . . . . . . 27

2.8 Possible different mechanisms individuated for roofs and tower. . . . . . . . 28

2.9 Example of cracks due to differential soil settlement. . . . . . . . . . . . . . 30

2.10 Tensions pattern for a wall due to the effect of subsidence . . . . . . . . . . 30

2.11 Mechanisms of the connection between roof and masonry. . . . . . . . . . . 31

3.1 Three different type of masonry damage . . . . . . . . . . . . . . . . . . . . 36

3.2 The equivalent frame model. . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3.3 Two different model of truss. . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3.4 A ”simple example”. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

3.5 A Screenshot of the definition of the walls geometry. . . . . . . . . . . . . . 39

3.6 A Screenshot of the panel to define the geometry of the openings. . . . . . . 40

3.7 A Screenshot of the panel to manage the different levels. . . . . . . . . . . . 41

3.8 A Screenshot of the walls definition for the fourth floor of the tower. . . . . 42

3.9 Parameters set to model roofs and vaults. . . . . . . . . . . . . . . . . . . . 43

3.10 Details of the church roof. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

3.11 Some drawings about the geometry of the roof trusses. . . . . . . . . . . . . 45

3.12 Parameters set to model roofs and vaults with 3Muri. . . . . . . . . . . . . 46

3.13 Two examples of test to determine the shear resistance of the masonry. . . 50

3.14 An example of compression test on site. . . . . . . . . . . . . . . . . . . . . 51

3.15 The test with two flat jacks. . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

4.1 The final model of the church used for obtaining the results. . . . . . . . . . 53

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List of figures ix

4.2 The equivalent frame mesh for the church. . . . . . . . . . . . . . . . . . . . 55

4.3 The equivalent frame mesh for the church. . . . . . . . . . . . . . . . . . . . 56

4.4 Ground motion parameters for the site. . . . . . . . . . . . . . . . . . . . . 57

4.5 Description of the soil around Zuidwolde. . . . . . . . . . . . . . . . . . . . 57

4.6 Modal analysis and ground motion parameters. . . . . . . . . . . . . . . . . 58

4.7 The analysis performed by the software. . . . . . . . . . . . . . . . . . . . . 60

4.8 Pushover for -Y direction for the tower . . . . . . . . . . . . . . . . . . . . . 61

4.9 Pushover for -Y direction for the church . . . . . . . . . . . . . . . . . . . . 61

4.10 Pushover for X direction for the tower . . . . . . . . . . . . . . . . . . . . . 62

4.11 Pushover for X direction for the church . . . . . . . . . . . . . . . . . . . . 63

4.12 A simple exercise: three different type of trusses . . . . . . . . . . . . . . . 64

4.13 The equivalent truss for the situation of Zuidwolde . . . . . . . . . . . . . . 65

5.1 Four categories of different local mechanism. . . . . . . . . . . . . . . . . . . 71

5.2 Two of the mechanism identified from the existing cracks in the southern

façade of the church . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

5.3 A detail of the node of the roof. . . . . . . . . . . . . . . . . . . . . . . . . . 73

5.4 The SAP2000 model of the roof trusses. . . . . . . . . . . . . . . . . . . . . 74

5.5 Shell elements in the model. . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

5.6 The response spectrum in the program SAP2000. . . . . . . . . . . . . . . . 76

5.7 The main modal shapes for the roof. . . . . . . . . . . . . . . . . . . . . . . 77

5.8 The modal periods and mass participation ratios from the software SAP2000. 77

5.9 Deformation of the roof due to the actions. . . . . . . . . . . . . . . . . . . 80

5.10 The static linear analysis and the static scheme used to evaluate the hori-

zontal load multiplier on the roof truss. . . . . . . . . . . . . . . . . . . . . 81

5.11 The loads acting on the static linear approach. . . . . . . . . . . . . . . . . 82

5.12 Two local mechanism calculated for the southern façade. . . . . . . . . . . . 85

5.13 Two local mechanism computed for the tower. . . . . . . . . . . . . . . . . . 87

6.1 The reinforced concrete slab solution. . . . . . . . . . . . . . . . . . . . . . 91

6.2 The results of the analysis performed after the intervention. . . . . . . . . . 92

6.3 The new floor with a concrete layer designed for the model. . . . . . . . . . 93

6.4 The pushover for the wall P1 after the intervention. . . . . . . . . . . . . . 94

6.5 The results of the case 19 at the last step of the pushover curve. . . . . . . 95

6.6 The pushover for the