THE MEASUREMENT OF FULL SCALE STRUCTURAL BEAM-COLUMN CONNECTION DEFORMATION USING DIGITAL CLOSE RANGE PHOTOGRAMMETRY TECHNIQUE

Measuring and monitoring of river channel evolution or changes under laboratory conditions is an important scope in hydraulic assessment. Measurement such as changes in river channel profile for instance, provides an important indicator on erosion and accretion rates in hydraulic modelling. Under controlled conditions, the changes in channel profile are usually measured using a high precision point gauge. However, when large numbers of points of river profile need to be measured, the use of point gauge method becomes laborious and time consuming. This study proposed a digital close range photogrammetry technique to measure natural river channel bed profile changes in laboratory. The objective of this study was to investigate the changes of physical river model profile for pre and post flooding simulations using digital close range photogrammetry technique. Small scale physical model experimental works were conducted in the Hydraulics and Hydrology Laboratory to observe the river profile evolution during the events. The flood flume utilized in this study is 4.95 m long, 1.38 m wide and 1.26 m deep with carved V-shaped natural main channel with a bed slope of 1:500. Data measured from digital close range photogrammetry technique during pre-flooding at t = 0 second and post flooding events at t= 9660 second were compared to determine the channel profile evolution or changes after simulation of flood event. The results show the changes in invert level or bed level between non-flooding and flooding events due to erosion is varies from 1 mm (minimum) to 6 mm (maximum) along the channel between chainage 0mm and chainage 2000 mm with total volume of erosion is 1157 x 103 mm3 respectively. It can be concluded that the digital close range photogrammetry technique can be used as a complimentary method to measure and monitor the changes of river channel profile in the laboratory

Estimating a mathematical formula of soil erosion under the effect of rainfall simulation by digital close range photogrammetry technique

Estimating a mathematical formula of soil erosion under the effect of rainfall simulation by digital close range photogrammetry technique

Measuring and monitoring of river channel evolution or changes under laboratory conditions is an important scope in hydraulic assessment. Measurement such as changes in river channel profile for instance, provides an important indicator on erosion and accretion rates in hydraulic modelling. Under controlled conditions, the changes in channel profile are usually measured using a high precision point gauge. However, when large numbers of points of river profile need to be measured, the use of point gauge method becomes laborious and time consuming. This study proposed a digital close range photogrammetry technique to measure natural river channel bed profile changes in laboratory. The objective of this study was to investigate the changes of physical river model profile for pre and post flooding simulations using digital close range photogrammetry technique. Small scale physical model experimental works were conducted in the Hydraulics and Hydrology Laboratory to observe the river profile evolution during the events. The flood flume utilized in this study is 4.95 m long, 1.38 m wide and 1.26 m deep with carved V-shaped natural main channel with a bed slope of 1:500. Data measured from digital close range photogrammetry technique during pre-flooding at t = 0 second and post flooding events at t= 9660 second were compared to determine the channel profile evolution or changes after simulation of flood event. The results show the changes in invert level or bed level between non-flooding and flooding events due to erosion is varies from 1 mm (minimum) to 6 mm (maximum) along the channel between chainage 0mm and chainage 2000 mm with total volume of erosion is 1157 x 103 mm3 respectively. It can be concluded that the digital close range photogrammetry technique can be used as a complimentary method to measure and monitor the changes of river channel profile in the laboratory

Meander dynamics has been the focus of river engineering for decades; however, it remains a challenge for researchers to precisely visualise natural evolution processes especially in alluvial plains. The evolution of meandering channels is a complex geomorphological process driven by the interactions between flow and alluvial channel beds and banks. The presence of vegetation along a riparian zone added the complexity of geomorphological process. Riparian vegetation is a major roughness element that influences channel morphology, decreases the average flow velocity and physically traps material that transported in alluvial rivers. A laboratory experimental investigation was carried out in Universiti Teknologi Malaysia in order to understand the flow behaviour and morphodynamics for a riparian vegetated flooded meandering channel. The morphological patterns visualisation and river channel profile changes estimation for pre and post flooding were obtained using digital close range photogrammetry technique. The findings prevailed that riparian vegetation had induced higher resistance to the flow and forced the flow to take place in main channel and right flood-plain while reduced the left floodplain flow velocity. The presence of riparian vegetation combined with the river bed morphology had increased the Manning’s n in left flood-plain. The influence of riparian vegetation on the sediment movement in the compound meandering channel was also identified. The sedimentation was 45% increased, while erosion decreased about 31% as the floodplain was roughened by vegetation.

Digital Elevation Models of soil surfaces are used in soil erosion research for a better understanding of erosion processes. Non-contacting techniques are used to avoid disturbance of the soil surface. So called laser scanners are used to obtain high-resolution grids (1 mm2/grid cell) from soil surfaces (up to 16 m2). The scanning devices are moving on a heavy reference frame and are thus not very practicable for field work. The time needed for one scan exceeds hours while soil surfaces may change within much shorter periods of time. For faster data acquisition and better versatility as well as for the coverage of large areas, photogrammetry is proposed to be an ideal surveying method. The system is not in contact with the soil surface, large areas can be covered by a block of images, and temporal resolution is determined by the time to take the necessary number of photographs. A camera can be easily transported on field location. This paper will describe the photogrammetric method under development at the National Soil Erosion Research Laboratory in cooperation with the University of Hanover, Institute for Engineering Surveys. The method is compared to one of the latest laser scanner devices. Results show that the photogrammetric technique is capable of reducing the time for data acquisition, of covering large areas large by combining multiple images, and that it has a better relative accuracy than the laser scanner.

In many cases of monitoring or load testing of hydrotechnical structures, the measurement results obtained from dial gauges may be affected by random or systematic errors resulting from the instability of the reference beam. For example, the measurement of wall displacement or pile settlement may be increased (or decreased) by displacements of the reference beam due to ground movement. The application of surveying methods such as high-precision levelling, motorized tacheometry or even terrestrial laser scanning makes it possible to provide an independent reference measurement free from systematic errors. It is very important in the case of walls and piles embedded in the rivers, where the construction of reference structure is even more difficult than usually. Construction of an independent reference system is also complicated when horizontal testing of sheet piles or diaphragm walls are considered. In this case, any underestimation of the horizontal displacement of an anchored or strutted construction leads to an understated value of the strut’s load. These measurements are even more important during modernization works and repairs of the hydrotechnical structures. The purpose of this paper is to discuss the possibilities of using modern measurement methods for monitoring of horizontal displacements of an excavation wall. The methods under scrutiny (motorized tacheometry and terrestrial laser scanning) have been compared to classical techniques and described in the context of their practical use on the example hydrotechnical structure. This structure was a temporary cofferdam made from sheet pile wall. The research continuously conducted at Wroclaw University of Science and Technology made it possible to collect and summarize measurement results and practical experience. This paper identifies advantages and disadvantages of both analysed methods and presents a comparison of obtained measurement results of horizontal displacements. In conclusion, some recommendations have been formulated, which are relevant from the point of view of engineering practice.

For the image quality analysis of photogrammetrical systems using the Modulation Transfer Function (MTF), the edge gradient analysis (EGA), using a Hanning function, and the grating pattern method are compared. Artificial edge and grating patterns were photographed from an airplane and were analyzed to determine the quality of the photogrammetric system. The pictures were scanned with a microdensitometer. For comparison with the artificial patterns, a natural roof edge was examined. Good agreement of all MTF measurements was found. Furthermore, the resolution found from MTF curves agreed well with the resolution obtained from three-bar targets. Generally, the MTF curves obtained from patterns in the flight direction were lower than the MTF's perpendicular to the flight direction due to airplane movement. The influence of linear image motion and its compensation was examined and is discussed. N PHOTOGRAMMETRY the image quality of photographs is of great importance. With digital image processing the image quality can be improved under certain conditions. Flight con­ ditions usually lead to reduced image quality (Holdermann, 1976). The optical transfer function (OTF) and especially the modula­ tion transfer function (MTF) are useful techniques for measuring the image quality of photographs. The MTF is the result of -the contributions of the links in the image transfer forming chain, namely, the camera, the film, image motion (in systems without forward motion compensation, FMC), vibrations, and the at­ mosphere (Tiziani, 1977). Artificial or natural edges are used for the edge gradient analysis (EGA), and varying spatial frequency patterns are used for the grating pattern technique. The aim of this paper is to compare both methods and to test their reliability. Results are shown and discussed. Furthermore, the influence of linear image mo­ tion on image quality is examined.

Structural dynamic displacement vision system using digital image processing

The article reports the interdisciplinary project of the virtualization of the Great Inscription of Gortyna (Crete) for 3D documentation, structural studies and physical replica purposes. The digitization of the longest epigraphic text of the Greek civilization (6 m long and 1.75 m high, with ca 2-3 mm depth engraved letters) and its surrounding heritage area (ca 30 x 30 m), required a long planning and the construction of a dedicated acquisition system to speed up the surveying time, limited to few hours per day. Primarily range sensors were employed in a multi-resolution way, digitizing detailed parts in highresolution and less smoothed areas with lower geometric resolution. Some selected areas were also modeled with our multi-photo geometrically constrained image matching approach to demonstrate that the same accuracy and details can be achieved using either scanners or photogrammetry. The derived 3D model of the heritage is now the basis for further archaeological studies on the incision techniques and a deeper structural analysis on the monument. The challenges of the work stay in the acquisition, processing and integration of the multi-resolution data as well as their visualization.

With the development of computer and surveying technology, Photogrammetry has run to Full Digital Photographic Measuration stage. As an embranchment of Photogrammetry, Close-range Photogrammetry plays a vital part in many aspects, for example the distortion observation, dynamic monitoring of buildings, and protection of cultural relics. This article emphasizes on introducing the methods for gaining high precision vertical surface geospace data of grottoes cliff with complicated physiognomy in large range and the application of Full Digital Photographic Measuration in cultural relics maintenance and rehabilitation through the project of digital Close-range Photogrammetry in Dunhuan Mogao grottoes cliff.

Time and accuracy required are the two important factors that decide on the appropriateness of volume calculations for road project, mining enterprise, geological works and building applications. Geodetic surveying methods have been insufficient for the volume calculation of the objects need to calculation of volume in a short time or in a risk area. In this paper, digital close range photogrammetry is an alternative method to volume calculation. The main objective of this paper is investigated the use of close range photogrammetry to calculate the volume instead of traditional methods. This paper gives also the sequence of the field operations and computational steps for this task. A numerical example is included to reinforce the theoretical aspects.

In this study, a double–decker finite element model has been analysed for the maximum stiffness of the full structure using the Taguchi method while maintaining the weight approximately unchanged. Through adjusting the distribution of the total structural weight on each sub–structure, redesigning the section property of major components of the structure and optimising the structural topology, the torsional stiffness is improved by 20.0% and the bending stiffness by 23.3%. This study verifies that the Taguchi method is effective in improving the stiffness of the full structure.

Automated fibre placement (AFP) machines are able to place simultaneously several bundles of fibres, called tows, on a surface. Using AFP machines, it is also possible to manufacture composite laminates with fibres placed in curvilinear paths. The fibre orientations and stiffness properties of these laminates are spatially varied and hence they are called variable stiffness (VS) laminates in contrast to the traditional laminates with straight fibres which are called constant stiffness (CS) laminates. Past research has shown that the structural performance of laminated composite structures can be improved by spatial tailoring of laminate stiffness. One of the widely used structural components in aerospace industry are cylindrical shells. In this thesis, a computationally efficient framework was developed for circumferential laminate stiffness tailoring of unstiffened and longitudinally stiffened cylindrical shells with arbitrary cross sections to maximise the buckling capacity with consideration of strength constraints. In addition, the AFP manufacturing constraint on the maximum curvature of curvilinear fibre paths was considered. This constraint was applied to avoid wrinkling of the fibres placed inside the turn of a curved tow. The aforementioned framework utilised computationally efficient analysis and optimisation tools.

This research investigates the collapse responses of a concrete moment frame considering modeling uncertainties. These modeling uncertainties are considered for evaluating a collapse response related to the modified Ibarra-Krawinkler moment-rotation parameters for beam and column elements of a given structure. To analyze these uncertainties, the correlations between the model parameters in one component and between two structural components were considered. Latin Hypercube Sampling (LHS) method was employed to produce independent random variables. Moreover, Cholesky decomposition was adopted to produce correlated random variables. Performing 281 simulations for the uncertainties involved considering their inter-correlations, incremental dynamic analysis (IDA) was done using 44 far-field accelerograms to determine structural collapse responses. Collapse responses of each simulation, including mean collapse capacity, mean collapse drift, and mean annual frequency, were obtained. Then, the collapse responses were predicted using the response surface method and artificial neural network. The results show that the Correlation coefficients (R) between the target data resulted from incremental dynamic analysis (IDA), output data resulted from response surface method (RSM), and artificial neural network (ANN) were obtained for the collapse responses above 0.98. The maximum prediction errors for mean collapse capacity and mean collapse drift are less than 5% and for mean annual frequency less than 10% under response surface method (RSM), and artificial neural network (ANN).