Data Mining Technology for Structural Control Systems: Concept, Development, and Comparison

Structural control systems are classified into four categories, that is, passive, active, semi-active, and hybrid systems. These systems must be designed in the best way to control harmonic motions imposed to structures. Therefore, a precise powerful computer-based technology is required to increase the damping characteristics of structures. In this direction, data mining has provided numerous solutions to structural damped system problems as an all-inclusive technology due to its computational ability. This chapter provides a broad, yet in-depth, overview in data mining including knowledge view (i.e., concept, functions, and techniques) as well as application view in damped systems, shock absorbers, and harmonic oscillators. To aid the aim, various data mining techniques are classified in three groups, that is, classification-, prediction-, and optimization-based data mining methods, in order to present the development of this technology. According to this categorization, the applications of statistical, machine learning, and artificial intelligence techniques with respect to vibration control system research area are compared. Then, some related examples are detailed in order to indicate the efficiency of data mining algorithms. Last but not least, capabilities and limitations of the most applicable data mining-based methods in structural control systems are presented. To the best of our knowledge, the current research is the first attempt to illustrate the data mining applications in this domain

Soil liquefaction hazard assessment along shoreline of Peninsular Malaysia / Huzaifa Hashim

The thesis provides a complete liquefaction potential hazard study for shoreline of 1972 km covering 40 shoreline districts of 11 major states of Peninsular Malaysia. Two main aspects are considered in defining soil liquefaction study which consists of regional geotechnical settings and regional seismicity information. 4 interrelating approaches are introduced in study; soil liquefaction screening, cyclic triaxial testing, earthquake study and liquefaction hazard mapping. In this study, governing factors contributing to soil liquefaction hazard were selected and adapted in soil liquefaction screening in highlighting soil liquefaction potential areas. The cyclic loading was applied on sand and clay samples to establish the shear modulus reduction curves and damping ratio curves that represents regional soil performance for seismic response. Probabilistic seismic hazard analysis (PSHA), spectrum matching procedure (SMP) and site response analysis (SRA) was adapted in seismic study in generating ground motion of studied sites. Soil liquefaction assessment approach based on Simplified Procedure was used in developing the hazard map for shoreline of Peninsular Malaysia. A mitigation chart is also introduced the in the study as a precursory measure in promoting safe built environment in the region. Findings revealed that shoreline area consist of vulnerable conditions to soil liquefaction hazard. The ground motion generated presents high amplification factor on the east coast region of Peninsular Malaysia specifically in the state of Terengganu and Kelantan. In general, the hazard map produced indicates that shoreline areas are vulnerable to soil liquefaction hazard. This soil liquefaction study will contribute towards promoting preparedness and enhanced awareness in the changing environment in today‘s context

Assessment of liquefaction hazard along shoreline areas of Peninsular Malaysia

Using a collection of 2074 boreholes extracted from soil investigation reports utilized by standard penetration test, this study examines the susceptibility of soil liquefaction hazard along the shoreline of Peninsular Malaysia. Data collection and site visit were conducted to gather all the basic information related to soil liquefaction hazard. Three types of results are presented in the form of photos (recent shoreline condition), graphical illustrations (soil composition, SPT-N distribution and zone of saturation) and liquefaction susceptibility plots. The findings indicate there is obviously a critical need to adapt further liquefaction analysis in the shoreline region of Peninsular Malaysia to better understand liquefaction hazard and produced beneficial information on the matter. A risk assessment matrix is also introduced in classifying the severity and recommended mitigation measures of the studied areas

A Review of Wind Clustering Methods Based on the Wind Speed and Trend in Malaysia

Wind mapping has played a significant role in the selection of wind harvesting areas and engineering objectives. This research aims to find the best clustering method to cluster the wind speed of Malaysia. The wind speed trend of Malaysia is affected by two major monsoons: the southwest and the northeast monsoon. The research found multiple, worldwide studies using various methods to accomplish the clustering of wind speed in multiple wind conditions. The methods used are the k-means method, Ward’s method, hierarchical clustering, trend-based time series data clustering, and Anderberg hierarchical clustering. The clustering methods commonly used by the researchers are the k-means method and Ward’s method. The k-means method has been a popular choice in the clustering of wind speed. Each research study has its objectives and variables to deal with. Consequently, the variables play a significant role in deciding which method is to be used in the studies. The k-means method shortened the clustering time. However, the calculation’s relative error was higher than that of Ward’s method. Therefore, in terms of accuracy, Ward’s method was chosen because of its acceptance of multiple variables, its accuracy, and its acceptable calculation time. The method used in the research plays an important role in the result obtained. There are various aspects that the researcher needs to focus on to decide the best method to be used in predicting the result

Nonlinear analysis of reinforced concrete slabs under high-cyclic fatigue loading

Infrastructures are frequently vulnerable to sustained cyclic loads and structural vibration. The accumulated cyclic stresses will induce fatigue in the structures and contribute to their inadequate service lifespan. Consequently, analyzing the present structural health status by the structural stiffness measurement is crucial. This study investigated the fatigue performance and dynamic progressive damage behavior of reinforced concrete (RC) slabs under high-cyclic fatigue loadings using nonlinear finite element (FE) analysis. A new model was recommended for predicting the concrete's residual strength. The accuracy of the suggested model and the FE simulation was validated by comparing the predicted natural frequencies, mode shapes, residual strength, and crack characteristics of specimens with the experimental results. Finally, a novel model for determining the dynamic stiffness of RC slabs was developed. Results showed that the cumulative degradation of the natural frequency, stiffness, and damage development of steel rebars and concrete increased as the fatigue loading cycle increased, indicating that the dynamic response and fatigue damage for RC slabs in the later stages of high-cyclic fatigue loading were more severe. Additionally, the RC slab's natural frequency was reduced rapidly during the initial steps of fatigue and, after that, slowed noticeably. Validation of the dynamic stiffness model demonstrated its capability in predicting the stiffness of fatigued and damaged RC slabs. The results provide practical insights for analyzing the dynamic behavior of existing structures by considering the nonlinear progressive damage and may improve the efficiency of structural damage detection

A review of the seismic performance behaviour of hybrid precast beam-to-column connections

In order to withstand challenges such as earthquakes, it is important to appropriately design the beam-to-column connection of precast structures. Numerous precast connections were designed to be used worldwide to attain satisfactory seismic performance. The failures observed for many beam–column connections were primarily due to the brittle behaviour of poor connection details between the precast concrete members. This review article examines past experimental studies which used hybrid precast connections comprised of three types: (1) dry and wet connections with steel sections (Type I), (2) composite concrete (Type II), and (3) composite concrete and steel sections (Type III). The seismic performance behaviour of these connection types was evaluated and compared with that of the monolithic connections. The analysis showed that both the dry semi-rigid and rigid connections Type I can be implemented in the seismic zones. In addition, most of the wet connections Type I, Type II, and Type III can simulate the behaviour of monolithic rigid connections. Therefore, the wet connections Type I, Type II, and Type III can withstand high seismic excitations. Overall, the performance of hybrid dry connection Type I can be improved by using strengthening technique methods in the connection to maintain the continuity of the PC beam. Moreover, the use of composite materials with and without the steel sections as connector elements in the connection (Type II and Type III) can be a feasible method to simulate the seismic performance of monolithic connections.</p

Simulating Intermediate Crack Debonding on RC Beams Strengthened with Hybrid Methods

The externally bonded (EB) and the near-surface mounted (NSM) are two well-known methods for strengthening reinforced concrete (RC) beams. Both methods are unfortunately prone to fail prematurely through debonding when the amount of strengthening reinforcement provided is high. In response to this, a hybrid method that combines the EB and NSM method was introduced. The method allows the amount of reinforcement needed for EB and NSM methods to be reduced; this, in theory, should lower the interfacial stresses, thus reducing the possibility of debonding failures. While debonding failure can be prevented, certain amounts of debonding would still occur through the interfacial crack (IC) debonding mechanism which can affect the strength and stiffness of hybrid strengthened beams even if it does not directly cause failure. This paper presents a method to simulate IC debonding of hybrid strengthened beams using the moment-rotation approach. The proposed method allows a better prediction of maximum load and stiffness of the beams. The method is also less dependent on empirical formulations compared to the commonly used moment-curvature approach; this allows the method to be applicable to all material and shape of hybrid strengthening reinforcement, assuming correct material models are used. The proposed method was then used to perform parametric studies; among the important findings is the length of IC debonding tend to increase when FRP sheet with higher elastic modulus is used, thus negating most of the benefit from the higher modulus

Effect of bonding materials on the flexural improvement in RC beams strengthened with SNSM technique using GFRP bars

In this paper, the effectiveness of cement mortar as bonding materials in the strengthening of reinforcements and concrete surface for flexural improvement of reinforced concrete (RC) beams were investigated. Recently, side near surface mounted (SNSM) and existing near surface mounted (NSM) techniques with glass fiber reinforced polymer (GFRP) bars are adopted as the strengthening methods for RC beams in which varieties of epoxy adhesive were replaced with cement mortar. In this study, one control and seven strengthened beams were tested under four-point loading in a static condition. The load-carrying capacities, failure modes, deflection, strains characteristic, parametric study and energy absorption capacities are addressed through laboratory experiments. The results revealed that the flexural performance was successfully achieved by using cement mortar as a replacement for adhesive. The SNSM strengthening technique exhibited better structural performance compared with the existing NSM technique in all aspects

Near Surface Mounted Composites for Flexural Strengthening of Reinforced Concrete Beams

Existing structural components require strengthening after a certain period of time due to increases in service loads, errors in design, mechanical damage, and the need to extend the service period. Externally-bonded reinforcement (EBR) and near-surface mounted (NSM) reinforcement are two preferred strengthening approach. This paper presents a NSM technique incorporating NSM composites, namely steel and carbon fiber-reinforced polymer (CFRP) bars, as reinforcement. Experimental and analytical studies carried out to explore the performance of reinforced concrete (RC) members strengthened with the NSM composites. Analytical models were developed in predicting the maximum crack spacing and width, concrete cover separation failure loads, and deflection. A four-point bending test was applied on beams strengthened with different types and ratios of NSM reinforcement. The failure characteristics, yield, and ultimate capacities, deflection, strain, and cracking behavior of the beams were evaluated based on the experimental output. The test results indicate an increase in the cracking load of 69% and an increase in the ultimate load of 92% compared with the control beam. The predicted result from the analytical model shows good agreement with the experimental result, which ensures the competent implementation of the present NSM-steel and CFRP technique

Ductility Enhancement of Sustainable Fibrous-Reinforced High-Strength Lightweight Concrete

To limit the cross-sectional size of concrete structures, high-strength, lightweight concrete is preferred for the design and construction of structural elements. However, the main drawback of high-strength, lightweight concrete is its brittleness over normal-weight concrete. The ductility of concrete is a crucial factor, which plays an important role when the concrete structures are subjected to extreme situations, such as earthquakes and wind. This study aims to improve the ductility of high-strength, lightweight concrete by incorporating steel fibers. The palm oil clinker (POC)-based, high-strength, lightweight concrete specimens reinforced with steel fibers were prepared and their ductility was systematically examined. POC was used as aggregates and supplementary cementitious materials. Steel fibers from 0–1.50% (by volume), with an increment of 0.5%, were used in the concrete mix. Compression ductility, displacement ductility and energy ductility were used as indicators to evaluate the enhancement of ductility. Moreover, the compressive strength, flexural strength, stress-strain behavior, modulus of elasticity, load-displacement characteristics, energy absorption capacity and deformability of the concrete samples were investigated. The compression ductility, displacement ductility and energy ductility indexes were found to be increased by up to 472%, 140% and 568% compared to the control specimens (concrete with 0% steel fibers), respectively. Moreover, the deformability and energy absorption capacity of the concrete were increased by up to 566% and 125%, respectively. Therefore, POC-based, high-strength, fibrous, lightweight concrete could perform better than conventional concrete under extreme loading conditions as it showed significantly higher ductility