He made a notable contribution to the unveiling of the Falling Weight Deflectometer (FWD) as a method for assessing rigid pavement structures and helped to raise awareness among British companies of its potential and limitations (Hughes & Karadelis, 1998). Proceedings of the Institution of Civil Engineers: Engineering and Computational Mechanics Tribune Terraces Experimental and Computational Modal Analysis.‟ Schrefler, B.A. ed.).
Context
Finally, highlight the author's contribution to research in general, and applied computational mechanics in particular, and the dissemination of the knowledge, experience and expertise gained.
AREAS OF INTEREST, JUSTIFICATION AND BRIEF REVIEW
At the same time, the long-established connections with the construction industry brought the author another kind of problem. In comparison, few researchers have addressed the full potential and applicability of the method, its utility, value and adaptability within different disciplines.
Sustainable Concrete Pavement Overlays
Therefore, another area of research emerged, that of Vibration of Stands due to human activities, with the aim of contributing to the study of their vibration behavior and ultimately solving the problem. Therefore, the author's idea of working through computational methods and techniques and using carefully planned laboratory and site tests solely for the calibration and validation of the FE models could be an innovation of significant value.
Grandstand Vibrations
Kasperski added that the dynamic loads caused by an active audience determine the design of stands or similar structures and that dynamic responses due to resonance with the first and second harmonics of the load can lead to significant safety problems. It has become clear that not enough work has been focused on accurate computer representation (modeling) of the structure itself, which is crucial if a realistic approach to the design of these structures is to be taken.
METHODOLOGY. COMMON THEMES OF THE SIX ARTICLES
However, the author's goal is to show that even a modest amount of data is sufficient if the finite element model is reliable. Although the author has always tried to familiarize himself with current literature and trends, most of the studied literature has brought rather general benefits, such as
Linking Six-Articles Together (the common approach)
The author referred to the effects of strain softening and noted that the popular cube/cylinder compression tests may not be representative to describe the stress-strain performance of concrete. He also referred to the solution procedure and commented on the suitability of Crisfield's method to represent the effects of strain relaxation.
AUTHOR’S OWN RESEARCH IN THE AREAS OF CONCRETE PAVEMENTS AND VIBRATIONS OF GRANDSTANDS
No. I, Journal Paper
- Rationale
- Contributions
- Benefits
- Originality
- Value, Impact, Citations
When soil condition information was available, the cubic spline was used, accurately predicting non-linear performance of the pavement system. The two-way computer representation of the soil layer (third degree spline using some experimental data, or an exponential function if no data were available) as part of a pavement structure has made a significant difference in the assessment and evaluation of concrete pavements.
No. II, Journal Paper
- Rationale
- Contributions
- Benefits
- Originality
- Value, Impact (difference), Citations
- Statement of Collaboration
Xiang & Chen (2006) also used the author's paper and adopted his axisymmetric numerical models. In another paper, the same researchers also used a modified version of the author's numerical model.
No. III, Journal Paper
- Rationale
- Contributions
- Benefits
- Originality
- Value, Impact
Specifically, the maximum displacement of the units measured at mid-span was found to be approximately the same for both uncracked and cracked units. This could have certain consequences for the design of the units, as the tread did not appear to be sufficiently reinforced in the location.
No.IV, Journal Paper
- Rationale
- Contributions
- Benefits
- Originality
- Value, Impact
In the present investigation, the main reinforcement shear strength problem was solved by determining the steel contribution to the surrounding aggregate. The author proposed a discrete reinforcement layout to address the shear resistance problem by choosing LINK8 elements.
No.V, Conference Paper
- Rationale
- Contributions
- Benefits
- Originality
- Value, Impact
He concluded that changes in dynamic properties may not be detected by increasing the amount of a strain. The role of reinforcement in the dynamic properties of a structure should be the basis for more research.
No.VI, Journal Paper
- Rationale
- Contributions
- Benefits
- Originality
- Value, Impact (citations)
Several parameters were found to affect the dynamic properties of the units and were included in the updating process. Essentially, in the case of modal analysis for evaluating the dynamic properties of a structure such as grandstand terraces, the author was able to point out that experimental procedures alone may actually be inadequate due to the complex way in which an unsymmetrical structure is designed. is likely to undergo.
SYNTHESIS
Paper I, „A Numerical Model for the Computation of Concrete Pavement Modul i‟
With the above-mentioned research, the author contributed to the unveiling and adoption of the Falling Weight Deflectometer (FWD) as a method for assessing and evaluating rigid (concrete) pavement structures. The disclosure of findings, benefits and shortcomings of the FWD to engineering firms and contractors.
Paper II, „Elasto-plastic FE Analysis with Large Deformation Effects of a T-plate Connection to Square Hollow Secti on‟
The author was able to improve the understanding of the behavior of these structures under different loading regimes. Nevertheless, the author has made the engineering community aware of the possible effects of the reinforcement in the dynamic properties of a structure.
Paper VI, Reliability Pointers for Modal Parameter Identification of Grandstand Terraces
A recommendation to use the finite element model updating procedure described in the article, as the method to extract the dynamic properties of structures. Ultimately, the author is fully aware of the limitations of his work, which are addressed in the next chapter.
CONCLUSIONS
The following two papers examined the under-researched area of reinforced concrete as a material, highlighted the strengths and weaknesses of all state-of-the-art numerical representations, and concluded by proposing a rigorous but practical numerical model for wider use. The conclusions of the various studies provided insights and recommendations that were useful for academics, engineers and students.
7.0 FUTURE
Proceedings of the Second International Conference on Carrying Capacity of Roads and Airports, Plymouth. The paper includes an extensive discussion of the above results and the conclusions drawn from them. It was estimated that the error involved was of the order of 11.6% in the linear region.
Engineering and Computational
Mechanics
Concrete grandstands. Part I: experimental investigation
Each unit is supported along the front edge by the lower unit riser. SG1 was attached to the transverse reinforcement and SG2 to the longitudinal tension reinforcement of the riser. This was also the rate of the corresponding deme pair for the uncracked unit in test 1.
Concrete grandstands. Part 11:numerical modelling
Linear and exponential mathematical models were used to describe the descending part of the stress-strain diagram. The element behaves linearly elastically if the applied tensile or compressive stress is less than the tensile or compressive strength of the material. If one of the applied principal stresses exceeds the tensile or compressive strength, however, cracking or crushing of the element begins.
STOP )
The initial slope of the curve was taken as the modulus of elasticity of the material (198 kN/mm2). In test 2 (cracked unit), the cracks inherited from test 1 improved the overall behavior of the unit. He also indicated a tendency for the unit to 'sink' in the middle and rotate around the horizontal.
Reliability Pointers for Modal Parameter Identification of Precast Concrete Terraces
INTRODUCTION
Civil engineering structures (eg stands), their boundary conditions and interaction with neighboring structures and sometimes their non-structural elements, form complex assemblies that play an important role in their dynamic performance and are difficult to model globally. This paper argues that the finite element method can play the leading role in extracting modal parameters of such structures and help reduce expensive, time-consuming and complex full-scale modal tests. To comment on the effect of steel reinforcement in the dynamic properties of these structures and identify any inherent patterns associated with the above.
MODAL ANALYSIS OF GRANDSTANDS (Brief overview)
To investigate and quantify the most effective parameters that influence the dynamic characteristics of the grandstand. Earlier, Ellis and Ji (1996) were involved in estimating the dynamic properties of structures. It is clear from the above that accurate and reliable finite element models to complement and verify the experimental identification and estimation of the modal parameters are in short supply today.
THEORETICAL BASIS
Swan, et al (2005) determined that support conditions are effective in influencing the frequency response function (FRF) measured on a model deck and that the FRF can be used as an accurate general indication of the overall stiffness condition of a bridge deck. Finally, Ibrahim and Reynolds (2007) demonstrated good correlation of natural frequencies and mode shapes and suggested that progressive modeling of different configurations is a fairly accurate approach in the FE modeling of large structures such as grandstands. In the case that the terrace units have no plane of symmetry, the problem becomes significantly more complex and involves coupled torsional and bending vibrations in the two principal planes.
FULL SCALE MODAL TESTING
- The Vibration Test System
- Test Programme and Methodology
In modal analysis, masses are used as data collection (reference) points (RPs) and the properties of the structure are determined by measuring the FRF (Frequency Response Function) at each of the RPs. Given the frequency response functions, it is possible to determine the natural frequencies and damping by locating the peaks of the FRF v Frequency plot or the Phase Shift v . A summary of the most important data acquisition parameters is given in Table 2 and a typical example of excitation and response time history is shown in Figure 4.
NUMERICAL MODAL ANALYSIS
- The Initial, ‘Static’ Model
- Updating Strategy, Correlation, Fine-tuning, Validation
- Initial FE Model
- First Update. (Material Properties)
- Second Update (Reinforcement)
- Third Update. (Support Stiffness)
- Forth Update (Block Lanczos)
- Fine Tuning
On the other hand, any differences in the density of the two materials can cause significant changes in the dynamic behavior of the units. Whether the latter are physically acceptable or not depends on the field of application of the model. Since the stiffness is directly related to the square of the natural frequency, the FE analysis is expected to overestimate the natural frequencies.
COMMENTARY ON THE RESULTS
This is only a 0.018 target improvement, but could easily be justified and incorporated into the update process.
UNCERTAINTIES IN MODAL ANALYSIS
CONCLUDING COMMENTS
Experimental Investigation”, Proceedings of the Institution of Civil Engineers, Journal of Computational Engineering and Mechanics 161, Issue EM1, doi: 101680/eacm. Numerical Modelling”, Proceedings of the Institution of Civil Engineers, Engineering and Computational Mechanics Journal 162, Issue EM1, doi: 101680/eacm. Dynamic Stiffness of Reinforced Concrete Beams”, Proceedings of the Institution of Civil Engineers, Structures and Buildings 156, , Number: SB4, 373-379.
Structuring
Intro
Closing Remarks
Outlook
Main Objectives
Sustainable Concrete Pavement Overlays
Areas of Interest
Grandstand Vibrations due to Human Movements
The Submitted Articles
A Numerical Model for the Computation of Concrete Pavement Moduli: A Non-destructive Testing
Added to existing knowledge by introducing material (bilinear) and geometric (LD) nonlinearities into numerical analysis. If the uncracked and cracked stiffness of the units were estimated experimentally and used as initial input in a. If realistic failure criteria (cracking-shattering, yielding) were integrated into the analysis, then the resulting models should be representative and the contribution to the subject significant.
Amplification can change the dynamic performance of a structure by returning from one mode of vibration to . Studying only parts of a large structure may not yield reliable conclusions about the dynamic performance of the latter (reviewed later). He is well aware of the limitations of his own research and the margins his numerical models use.
Green Overlays. Through his research (four) students and the relevant EPSRC grant he currently holds
