The purpose of this monograph is to present the results of the studies that were conducted, in order to assess the potential, and to formulate the rules (conditions) for determining the vibrations and displacements of civil engineering structures with the use of ground-based radar interferometry.
The reason for undertaking research on the modern surveying technology are the words of Professor Lazzarini: “The current surveying technique uses not only the traditional instruments, but increasingly adapts instrumental concepts of modern physics, so that the definition of determining displacements using surveying methods should not imply restrictions as to the selection or development of the construction concepts of surveying instruments, nor to the
surveying methods and calculations, but it should emphasize the geometric nature of the obtained results, proper to the surveying technique” (Lazzarini et al., 1977).
According to these words, the solution proposed by the manufacturer may lead to the introduction of a method for surveying displacements of a new quality in place of the methods previously used in engineering surveying. It can also be extended by the issue of determining vibrations. Popularization
of the new instrument should, however, be preceded by some basic research into its real surveying possibilities. The accuracy, range and resolution of the device require verification. The work will present surveying procedures to verify the above quantities, determine their actual value based on practical tests, and determine the suitability of the device for the surveying of vibrations and displacements of building structures.
- Spis treści
-
1. Introduction, purpose and scope of work 7
2. Static and dynamic displacements with elements of the methods of their analysis 10
2.1. Introduction 10
2.2. Displacements 10
2.3. Deformation 13
2.4. Loads occurring while surveying engineering structures 15
2.4.1. Vertical loads 16
2.4.2. Wind load 17
2.4.3. Thermal loads 19
2.5. An outline of mechanical system vibrations 22
2.5.1. Introduction 22
2.5.2. Simple harmonic motion 23
2.5.3. Damped oscillator 27
2.6. Digital signal 32
3. Control of the shape and location of engineering structures 41
3.1. Introduction 41
3.1.1. Periodic surveying and monitoring 41
3.1.2. Research-assisted design 43
3.2. Surveying of static displacements 44
3.2.1. Review of the requirements 44
3.2.2. Bridge structures 44
3.2.3. High structures 46
3.3. The meaning and scope of vibration measurement 47
3.3.1. Building requirements 47
3.3.2. Vibration surveys of buildings 49
3.3.3. Dynamic testing of bridge structures 51
3.3.4. Dynamic testing of high engineering structures 53
3.4. Methods for surveying displacement and vibration 55
3.4.1. Elements of metrology 55
3.4.2. Mechanical sensors 58
3.4.3. Electrical sensors 59
3.4.3.1. Inductive sensors 59
3.4.3.2. Strain gauges 61
3.4.3.3. Capacitive sensors 63
3.4.3.4. Photoelectric sensors 64
3.4.3.5. Lidar sensors 66
3.4.3.6. String potentiometers 66
3.4.3.7. Piezoelectric sensors 67
3.4.4. Surveying methods 67
3.4.4.1. Precision levels 68
3.4.4.2. Electronic total stations and scanners 69
3.4.4.3. Satellite positioning techniques 70
3.4.4.4. Photogrammetric methods 70
3.4.4.5. Other surveying instruments 71
4. Ground-based IBIS interferometric radar 73
4.1. Introduction 73
4.1.1. Basics of echolocation systems 73
4.1.2. Application of radars in displacement measuring 76
4.2. The construction and operation of the IBIS radar system 78
4.2.1. Application of the IBIS system 78
4.2.2. General description of the IBIS system elements 81
4.2.3. Characteristics of a signal used in the IBIS system 85
4.2.4. Characteristics of antennas used in the IBIS system 90
4.3. Principles for surveying and processing the results from the IBIS system 95
4.3.1. Surveying with IBIS-S CONTROLLER software 95
4.3.2. Processing data from IBIS-S in IBIS Data Viewer 101
4.3.3. Operation of the IBIS-L system 109
5. Influence of physical factors on the surveying accuracy of displacements 116
5.1. Physical factors determining the performance of the IBIS system 116
5.2. Influence of the atmosphere 121
5.3. Testing of radar range 126
5.3.1. Test in the free space 126
5.3.2. Test on a real structure 129
5.3.3. Assessing usable range of the IBIS-L system 134
5.4. Influence of the reflecting surface 137
5.4.1. Influence of the surface type on the results of observations – IBIS-S 137
5.4.2. Influence of the type of surface on the results of observations – IBIS-L 143
5.5. Testing of signal stability 146
5.6. Influence of characteristics of antennas 150
5.6.1. Verifying the actual characteristics of antennas 150
5.6.2. Influence of antenna selection on structure observation using the IBIS-S system 152
5.6.3. Influence of antenna selection on structure observation using the IBIS-L system 154
5.7. Testing of range resolution 157
6. Evaluating the accuracy of the IBIS interferometric radar 164
6.1. Introduction 164
6.2. Verification of the displacement survey accuracy using the IBIS-S system 165
6.2.1. Comparison with a laser interferometer 165
6.2.2. Surveys using a precision total station and reference reflector 169
6.2.3. Comparison with the laser vibrometer 174
6.3. Verification of the displacement survey accuracy using the IBIS-L system 180
6.4. Verifying the accuracy of determining vibration frequency 187
7. Surveying of static displacements and vibrations of bridge structures 192
7.1. Introduction 192
7.2. Test loads 195
7.2.1. Description of the test structure 195
7.2.2. Static load tests 196
7.2.3. Surveying dynamic test loads 200
7.3. Operational loads 207
7.4. Summary 213
8. Surveying of static displacement and vibration of high structures 214
8.1. Introduction 214
8.2. Static surveys 216
8.2.1. Industrial smokestacks 216
8.2.2. Telecommunications masts 221
8.2.3. Telecommunications towers 224
8.3. Dynamic surveys 228
8.3.1. Telecommunications masts 228
8.3.2. Industrial stacks 232
8.3.3. Shaft towers 236
8.4. Summary 239
9. Surveying of displacements of monolithic structures 240
9.1. Introduction 240
9.2. Planning of a survey 242
9.3. Initial surveys 245
9.4. Current surveys 249
9.5. Analysis of survey results 252
9.6. Conclusions 254
10. Summary 255
References 257