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The study aims to investigate the effectiveness and failure modes of using CFRP-bonded sheets as a flexural repair system for RC beams, considering the effect of pre-repair damage levels and flexural steel design limits. This study investigated two different flexural design criteria: RC beams reinforced with the minimum flexural steel limit (ρmin) and RC beams reinforced with the maximum flexural steel limit (ρmax). Additionally, three pre-repair damage levels were considered: design limit load, steel yield limit load, and failure limit load. The study results showed that the RC beams’ repair effectiveness depends on the ratio of the flexural steel provided. Specifically, the beams with a minimum steel ratio demonstrated a higher capacity restoration of 49% to 85% (corresponding to the pre-repair damage level, i.e., design load to failure load), while beams with a maximum steel ratio only achieved a capacity restoration of 15.3% to 28.4%. Regarding failure modes, the beams experienced an intermediate-induced crack (IC) debonding due to pre-repair flexural cracks. Despite the debonding of the CFRP sheets, the beams still had the ability to withstand loads close to their unrepaired capacity. This indicates the possibility of re-repairing the beams after the CFRP debonding. Overall, the findings of this study can be used in the industry to repair RC beams and girders that have been damaged due to extreme loading conditions or other reasons. By using CFRP externally bonded sheets, the capacity of the structures can be restored regardless of the pre-repair damage level and the flexural steel design criteria.

In recent years, data mining technology has been employed to solve various Structural Health Monitoring (SHM) problems as a comprehensive strategy because of its computational capability. Optimization is one the most important functions in Data mining. In an engineering optimization problem, it is not easy to find an exact solution. In this regard, evolutionary techniques have been applied as a part of procedure of achieving the exact solution. Therefore, various metaheuristic algorithms have been developed to solve a variety of engineering optimization problems in SHM. This study presents the most applicable as well as effective evolutionary techniques used in structural damage identification. To this end, a brief overview of metaheuristic techniques is discussed in this paper. Then the most applicable optimization-based algorithms in structural damage identification are presented, i.e. Particle Swarm Optimization (PSO), Genetic Algorithm (GA), Imperialist Competitive Algorithm (ICA) and Ant Colony Optimization (ACO). Some related examples are also detailed in order to indicate the efficiency of these algorithms.

This paper develops and applies a procedure for detecting damage in a composite slab-on-girder bridge structure comprising of a reinforced concrete slab and three steel I beams, using vibration cha...

In this study, grouted couplers were used to connect steel bars as an alternative approach to the conventional steel bar lapping method. The aim is to avoid bar congestion problems and to reduce the required quantity of steel bars in order to achieve the development length in practice. Two categories of couplers, i.e., short-threaded grout coupler and long grout coupler, in nine groups as well as one group of deformed bars, were tested under uniaxial tension. In total, 30 samples (including three repeated samples in each group) were tested. The examined parameters were types of couplers, embedded bar length, and bar eccentricity. For the short-threaded grout couplers, the embedded bar length, which is equivalent to 8 times bar diameter with bar eccentricity equal to zero, exhibited the best performance in terms of strength, ductility, energy absorption, and failure mode, which is suitable to be used in the high seismic zone. Additionally, the short-threaded grout couplers with the embedded bar length equal to 7 times bar diameter and the long grout couplers that required embedded bar length that is equal to 8 times bar diameter, are suitable to be used in the low-to-medium seismic zone. Besides, the embedded bar length that is smaller than or equal to the 6 times bar diameter was not sufficient to be utilised in the short-threaded grout couplers and long grout couplers to resist the seismic load due to inadequate bar embedded length. Also, the predicted model is sufficient to estimate the ultimate tensile strength of the grouted couplers.

Technical benefits relevant to the use of palm oil clinker (POC) and fuel ash (POFA) in building materials has been well documented. However, the radiological health hazards caused by the incorporation of POC and POFA as an ingredient of building materials have not been studied so far. The radioactivity levels were measured by γ-ray spectrometry using hyper-pure germanium (HPGe) detector. The activity concentration of 226Ra and 232Th in POC and POFA was found to be in the ranges of 5.56 ± 0.23 to 9.03 ± 0.21 and 4.21 ± 0.03 to 7.98 ± 0.19 Bq kg−1, respectively, and these values were lower than the world average values of 50 Bq kg−1 for building materials. The 40K value was within the range of 413.01 ± 1.78 to 604.66 ± 2.18 Bq kg−1. Several radiological parameters and hazard indices, i.e. radium equivalent activity, absorbed dose rate and annual effective dose etc. were calculated for the evaluation of the potential radiological hazards. The obtained values fall within the recommended limit set by various international organizations. Since the activity levels of 226Ra, 232Th and 40K in POC and POFA were significantly lower than the corresponding literature data for other ingredients of building materials, it indicates that POC and POFA are safe to be used in concrete construction.

Utilization of locally available waste and by-product to replace conventional concrete materials has gained considerable attention over the past two decades. This study is a part of an extensive research program on the characteristics of palm oil clinker (POC) incorporated concrete. In this study, experimental investigation was carried out on incorporating POC as aggregates and filler material in the production of high strength concrete (HSC). Crushed POC were used as partial and full replacement of natural aggregates i.e. fine and coarse. Palm oil clinker powder (POCP) was then incorporated to fill the voids present on the surface of POC particles, while maintaining the other mix constituents. Fresh and hardened properties of the POC concrete with and without POCP were investigated. Substituting coarse aggregate with POC negatively affected the concrete fresh and hardened properties due to POC porous nature. However, the results of the study revealed that incorporating additional POCP as filler material by adopting Particle-Packing (PP) method improved the engineering properties of POC concrete. Therefore, there is a potential towards utilization of POC for many practical construction applications. POC being an environmentally-friendly and a low-cost aggregate can serve as a normal aggregate alternative for future use.

Technical benefit of incorporation of Palm Oil Clinker (POC) in cement-based applications has been proven in recent studies. The aim of this work was to assess the heavy metal leaching behavior to ensure environmental safety of using POC in cement-based applications. The chemical composition, morphology, total organic carbon (TOC) and mineralogy were determined using XRF, FESEM, TOC analyzers and XRD to select appropriate chemical reagents for complete digestion. HNO3, HF and HClO4 were used for digestion of POC to measure heavy metal content using ICP-MS. The chemical reagents CH3COOH, NH2OH-HCl, H2O2+CH3COONH4 and HF+HNO3+HCl were used for extraction of acid soluble, reducible, oxidizable and residual fractions of heavy metals in POC, respectively. The leaching toxicity of the POC was investigated by the USEPA 1311 TCLP method. The result showed the presence of Be, V, Cr, Ni, Cu, Zn, As, Se, Ag, Cd, Ba and Pb with levels of 5.13, 11.02, 2.65, 1.93, 45.43, 11.84, 15.07, 0, 0, 81.97 and 1.76 mg/kg, respectively, in POC. The leaching value in mg/L of As (4.56), Cu(1.05), Be (0.89), Zn(0.51), Ba(0.26), Ni (0.17), V(0.15), Cr(0.001) and Se (0.001) is found well below the standard limit of risk. Risk assessment code (RAC) analysis confirms the safe incorporation of POC in cement-based applications.

In this paper, we demonstrate a single-mode–multimode–single-mode (SMS) fiber structure to measure compressive strain in the elastic regime of a reinforced concrete beam. The fabrication method used to produce a 3.12 m reinforced concrete beam that met the Euro code (EC2) requirements was also demonstrated in this work. Strain measurement via the SMS sensor was calibrated using an electrical resistance strain gauge and a data logger to obtain accurate measurements of the strain. A linear transmission spectral red shift was observed as the strain value was increased from 0 mm/mm to 0.000116 mm/mm. Hence, the SMS sensor could provide a sensitivity of 3778.1 nm/(mm/mm) with a linearity of 0.9661.

The management of waste material from various industries has been given importance in recent times to create a cleaner environment and sustainable industrial atmosphere. Palm oil clinker (POC), one of the by-products from the incineration process of oil palm shell and fibres in the palm oil mill boilers, has the potential to pollute the environment if not managed appropriately. In this study, the applicability and feasibility of POC fine as a substitute for sand was investigated thoroughly at different replacement levels (0%, 12.5%, 25%, 37.5%, 50%, 62.5%, 75%, 87.5% and 100%). It was found that complete replacement of sand with POC fine has the ability to produce almost 78% of the strength compared to the conventional mix at 56 days. From the perspective of durability, POC fine can produce almost 97% of the long lasting effect with regards to the control mix. The assessment of sustainability shows that POC fine can enhance the engineering environmental index and engineering economic index by 95% and 11%, respectively. Life cycle impact assessment (LCIA) performed proves the ability of POC to promote cleaner and safer environment. This research reveals that POC fine can be regarded as a highly beneficial material contributing substantially towards the sustainability and preservation of sand as a natural resource even when completely substituted.

In general, precast concrete structure has insufficient ductility to resist seismic load. Detailed understanding on the behaviour of precast concrete connections are limited and current researches are focused addressing this. In this study, two precast and two monolithic concrete joints for exterior beam-to-column connection were tested under cyclic loading. The installation of precast specimens was prepared using dry type method while the monolithic joints were casted in-situ. The evaluation of seismic performance of the joints was conducted by applying hysteretic reverse cyclic loading until failure. Information regarding the strength, ductility and stiffness properties of the connection were recorded and analysed. Based on the test results and damage condition, the initial design of the joint was improved. Consequently, a new joint was constructed and tested, which exhibited a better performance. Precast concrete connections showed stable load–displacement cycles and dissipated a higher energy. The structural drift obtained was up to 9.0%. Pinching and deterioration were attained at a drift ratio of 4.5%. Also, there was improvement in the tested precast joints based on deflection, plastic hinges, crack pattern and shear deformation. Thus, the precast joints had a satisfactory resistance to seismic loads.

This paper investigates the abrasion resistance and strength properties of pervious concrete (PC) containing palm oil clinker (POC) coarse aggregate under different curing method. Materials used include OPC Type I, 10 mm nominal size POC coarse aggregate and granite. The palm oil clinker pervious concrete (POCPC) mixes were developed with a fixed water-cement ratio of 0.3 and was studied at various replacement levels of natural aggregate with POC aggregate (0%, 25%, 50%, 75% to 100%). Selected curing methods for the POCPC samples were full water curing, air curing and 3 days water curing respectively. Based on results, compressive strength and abrasion resistance of the POCPC reduced, resulting from the incorporation of POC into the mix irrespective of the curing method. Given the selected curing method, POCPC cured in full water had superior performance in terms of compressive strength. However, the POCPC cured in air and 3 days water curing recorded about 5% loss of its compressive strength with respect to full water curing due to uncontrolled temperature and humidity condition. Abrasion resistance of the concrete was improved when full water curing was adopted with about 5% loss due to curing method. Thus, it becomes evident that curing had marginal effect on the properties of the concrete rather it is dependent mainly on the properties of the aggregate. Furthermore, incorporating POC as an alternative concreting material can help to sustain the construction industry based on the sustainability efficiency evaluation conducted.

This study focuses on seismic vulnerability assessment of reinforced concrete buildings designed by considering only gravity loads. Fragility curves are developed for a three-story reinforced concrete office frame building and a four-story reinforced concrete school building with unreinforced masonry infill walls representative of the essential facilities in Malaysian Peninsula. A simplified modeling approach is adopted for fragility analysis, which can effectively reduce the computational effort. A set of fragility curves are developed in terms of peak ground acceleration with lognormal cumulative distribution functions. The fragility analysis shows that the seismic performance of the structures met the desirable performance level recommended by current seismic code, demonstrating low vulnerability of the structures within Malaysian Peninsula. It is also shown that the soil condition should be taken into consideration for effective seismic vulnerability assessment. Finally, the fragility curves developed in this study are compared to those of HAZUS.

Palm oil clinker (POC) is a waste material produced as result of using palm oil shell and mesocarp fibers as fuel to run stream turbines in palm oil mills. The current practice is to dump this waste in open land or landfill sites, which leads to environmental problems. The characterization of such waste to identify its suitability as a cement replacement materials, can ultimately lead to lower carbon footprint concrete. This paper presents the results of a study on the physical properties (particle size, specific surface, specific gravity, loss of ignition, morphology), chemical composition, organic carbon, thermal stability and mineralogical composition of palm oil clinker powder (POCP). The characterization was carried out using particle size analyzer, scanning electron microcopy (SEM), X-ray fluorescence (XRF), field emission scanning electron microcopy and energy-dispersive X-ray analysis (FESEM-EDX), thermogravimetric analysis (TGA), total organic carbon (TOC) analysis, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. From the laboratory works conducted results are defined and compared to existing literatures in tabulated form. The results of this extensive study on POCP characterization will provide guidance on future research work on utilization of POCP as a supplementary cementitious material in concrete.

This study is an experimental investigation into the properties of adhesive before and after mixing with fine sand, and its behavior on reinforced concrete beams strengthened by CFRP to show the effects of modified adhesive on load-carrying capacity, ductility, stiffness and failure mode of the reinforced concrete beams. Compressive strength, flexural strength and the effect of high temperature on these properties were the focus of the current study in order to prove the efficiency of adding fine sand to improve adhesive properties and reduce cost. Based on the compressive and flexural tests, results indicated that the addition of sand to the adhesive improved its mechanical properties when sand is 50% of the total weight of the adhesive. However, its effect on the modulus of elasticity is minimal. Using adhesive with fine sand increased the ultimate load bearing capacity, ductility, stiffness and toughness of the reinforced concrete beams strengthened by CFRP. The ratio of the fine sand to the adhesive equal to 1 is considered the best in terms of the cost reduction, maintaining workability, as well as maintaining the mechanical properties. Lastly, the use of fine sand with adhesive ensured a significant reduction in the cost of the adhesive and increased the adhesive resistance to temperature.

Palm oil clinker (POC) is a waste material produced as result of using palm oil shell and mesocarp fibres as fuel to run stream turbines in palm oil mills. The current practice is to dump the waste in open land or landfill sites, which leads to environmental problems. The suitability of using the palm oil clinker powder (POCP) in concrete as well as blended cement largely depends on its pozzolanic activity. In the present study, the pozzolanic activity of POCP has been investigated using X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) techniques, and compressive strength activity index measurement. The microstructure of the hydrated cement paste was observed using field emission scanning electron microscopy (FESEM). In order to evaluate the pozzolanic activity of the POCP, the pastes were prepared with ordinary Portland cement (OPC) at the level of substitution of 30%. The fluidity of the paste was maintained at 110 ± 5 mm. The strength activity index was evaluated according to ASTM standard. The microstructure properties investigation found that the portlandite (Ca(OH)2) react with SiO2 of POCP and formed C-S-H gel for strength development. This observation and strength activity index result confirmed that POCP is a pozzolanic material.

Palm oil clinker (POC), a by-product of palm oil mill, can be found in large quantity in Malaysia and it is considered as waste. POC is suitable as aggregate replacement in lightweight concrete and other engineering applications due to its physical properties. This study presents the use of POC as coarse aggregate in the production of pervious concrete (PC). Materials used include OPC Type I, coarse aggregate 10 mm nominal size. Based on this, various mixes were developed with a fixed water-cement ratio of 0.3. The palm oil clinker pervious concrete (POCPC) were studied at various replacement levels of natural aggregate with POC aggregate ranging from 0% to 100%. Results indicated that substitution with POC reduced the compressive strength and density of the concrete. However, the coefficient of permeability and porosity rose. Compressive strength obtained was between 3.43 MPa and 9.52 MPa. Maximum loss in strength was about 65% at full replacement. However, replacement of POC at 25% exhibited a superior performance among others. As such, it has been identified as the best mix for optimum performance of the POCPC.

Utilizing waste material in the construction industry is an effective way to protect the environment and minimize construction cost. In this paper, palm oil clinker (POC) aggregates were used as coarse and fine aggregate replacement in lightweight concrete production. This study focused mainly on investigating the effect of both partial and full replacement of the aggregates with POC on the physical and mechanical properties of concrete. Department of Environment (DOE) method was adopted for the mix design to produce concrete Grade 40. The approach used in the mix design involved POC replacement of 0%, 10%, 20%, 40%, 60%, 80%, and 100% of the total volume of fine and coarse aggregates. The parameters investigated in this study include the slump and density for the fresh properties, as well as the compressive strength and ultrasonic pulse value (UPV) tests at 3, 7, 14, and 28 days for the hardened properties. The hardened density at 28 days was within the range of 2074–2358 kg/m3. Test results showed that POC exhibited good UPV value and an acceptable compressive strength of 33–49 MPa at 28 days. Thus, POC has a good potential to replace natural aggregates, making it suitable to be used in concrete.

This paper investigates the effects of engineered cementitious composite (ECC) on the behavior of RC exterior beam–column joint under reversed cyclic loading. The main parameters considered include the load–deflection relationship, crack propagation, moment–rotation relationship at the joint, and energy absorption capacity. The experimental work was conducted on a normal concrete and an ECC full scale RC exterior beam–column joint. The specimen was subjected to reverse cyclic loading under controlled deformation at the tip of the beam until failure. At post cracking stages, the ECC joint showed significant improvement in the ultimate shear and moment capacities, as well as in the deformation behavior and damage tolerance, compared with the NC specimen at ultimate and failure stages. Numerous tiny cracks with reduced crack width and spacing forming a dense of network propagated within the joint region.

Structural connection systems are a major challenge for precast construction systems. A dowel system requires designers to have sound knowledge of the fundamental requirements for seismic loads. In addition, it is important to consider unforeseen impact loads to prevent buildings from collapsing in the event of an earthquake. At present, the available building codes does not offer a complete design and analysis requirements for beam-to-column connection systems. Thus, this article provides researchers with a comprehensive review of the literature of the dowel precast beam-column connections. The key areas covered in this review are as follows: (1) studies on the behaviour of precast dowel beam-column connection systems in earthquake-prone areas; (2) studies on the design and development of precast dowel connection elements; (3) an evaluation of the effect parameters in precast connection systems and (4) a determination of the appropriate precast beam-to-column connections for seismic loads. The strength, ductility, energy dissipation, rotation and plastic hinges of joints in critical regions were considered in order to evaluate the performance of the dowel connection system.

Currently, visual inspections for damage identification of structures are broadly used. However, they have two main drawbacks; time limitation and qualified manpower accessibility. Therefore, more precise and quicker technique is required to monitor the condition of structures. To aid the aim, a data mining based damage identification approach can be utilized to solve these drawbacks. In this study, to predict the damage severity of single-point damage scenarios of I-beam structures a data mining based damage identification framework and a hybrid algorithm combining Artificial Neural Network (ANN) and Imperial Competitive Algorithm (ICA), called ICA-ANN method, is proposed. ICA is employed to determine the initial weights of ANN. The efficiency coefficient and mean square error (MSE) are used to evaluate the performance of the ICA-ANN model. Moreover, the proposed model is compared with a pre-developed ANN approach in order to verify the efficiency of the proposed methodology. Based on the obtained results, it is concluded that the ICA-ANN indicates a better performance in detection of damage severity over the ANN method used only.

The utilization of waste materials from the palm oil industry provides immense benefit to various sectors of the construction industry. Palm oil clinker is a by-product from the processing stages of palm oil goods. Channelling this waste material into the building industry helps to promote sustainability besides overcoming waste disposal problems. Environmental pollution due to inappropriate waste management system can also be drastically reduced. In this study, cement was substituted with palm oil clinker powder as a binder material in self-compacting mortar. The fresh, hardened and microstructure properties were evaluated throughout this study. In addition, sustainability component analysis was also carried out to assess the environmental impact of introducing palm oil clinker powder as a replacement material for cement. It can be inferred that approximately 3.3% of cement production can be saved by substituting palm oil clinker powder with cement. Reducing the utilization of cement through a high substitution level of this waste material will also help to reduce carbon emissions by 52%. A cleaner environment free from pollutants can be created to ensure healthier living. Certain industries may benefit through the inclusion of this waste material as the cost and energy consumption of the product can be minimized.

This paper introduces a procedure where the free-scaled Legendre wavelets are improved for dynamic analysis of spatial trusses. The operational matrices of integration for free scales of Legendre wavelets are presented and applied for time history analysis. For this aim, a clear-cut formulation is derived from decomposition of the only transitional responses of structures. The free-scaled operational matrices of Legendre wavelets accurately transfer the second-ordered differential equations of motion into the corresponding algebraic equations. Accordingly, a simple procedure is developed to compute dynamic responses of large-scaled spatial trusses. The applicability and effectiveness of the proposed procedure using Legendre wavelets are demonstrated with two numerical applications. Subsequently, results were compared with those from common time integration schemes such as Wilson-θ, Newmark-β, central difference and Duhamel integration methods. It is deduced that because of the inherent shape functions of Legendre wavelets the dynamic analysis is optimally achieved with the highest accuracy, best computational competency and with the lowest storage capacity.

This research investigated the effects of polyethylene (PE) fibers on the toughness and compressive and flexural strengths of engineered cementitious composite (ECC) cubes and slabs. In particular, this study discussed the reinforcing index (R.I.) as the main parameter. Tests were conducted in direct tension to evaluate the strain-hardening behavior of ECC with different PE fiber contents. Flexural toughness was also assessed following the ASTM C1018 procedure and post-cracking strength technique (PCSm). Results showed that the compressive strength linearly decreased with the increase of the reinforcing index, which in turn decreased the first crack load and significantly increased the ultimate load and failure deflections, and the ultimate strength of slabs. The toughness indices I20 to I100 significantly increased with the increase in reinforcing index and even exceeded the considered limitations. Based on the observed results, a new definition for the ECC PE was proposed as an extension to the definition given in ASTM C1018. All the residual strength factors increased when the reinforcing index increased, indicating a higher amount of the retained strength. Similarly, the retained strength had a higher amount when the PCS24 values increased with increase in the reinforcing indices. Keywords: Engineered cementitious composite (ECC), Polyethylene (PE) fibers, Aspect ratio (A.R.), Reinforcing index (R.I.), Toughness index, Post-cracking strength (PCSm)

There are significant changes in the dynamic responses of damaged structures in which the damage depth becomes influential. This fact enables the recognition of damages in structures from their dynamic response data. This paper aims to identify damage locations as well as quantification of damage extent utilizing a vibration-based method. In this work, a signal-based damage identification procedure using the information entropy of wavelet packet energy is employed to evaluate beam-like structures. Damage indices called singular wavelet packet entropy and relative wavelet packet entropy are proposed to identify the location and to quantify the structural damage. The method involves two steps: firstly, the singular value of wavelet packet entropy, which reveals the abnormality distribution of the energy in signal time-frequency domain and secondly, relative wavelet packet entropy that is an acceptable damage feature to examine damage location and quantitative evaluation of the extent of damages through the vibration signals. The effects of wavelet type and decomposition level on the detection of damage location are examined. Numerical and experimental results from four test beams are used to verify the viability of this method. Results show that the damage indices method has great potential in identification of location and depth of cut in a steel beam. The procedure can be used for health monitoring of other complex structures.

In this paper, the effectiveness of the modified Chebyshev and cubic spline׳s iterative methods is comparatively evaluated on geometrically non-linear analysis of truss structures. For the purpose of a comprehensive comparison, we have also proposed an iterative method free from second derivative originated from modified Chebyshev and cubic spline׳s schemes. The method involves a set of predictor–corrector schemes constructed by Chebyshev as the predictor for spline correctors to improve the approximation of the tangential stiffness matrix. The numerical assessment of the proposed method lies on three-step algorithm with satisfactory convergence of results. The analysis of convergence is carried out and is shown that the proposed method is at least third-order convergent. A simple step-by-step algorithm is developed capable of tracing the non-linear equilibrium curve until the first limit point through an incremental approach. The robustness and efficiency of the proposed schemes are comparatively investigated against classical Newton–Raphson׳s method for solving practical non-linear problems. It is concluded that for the large structural systems, where a large-scaled stiffness matrix is being iteratively updated, the best computational time, thus the optimum cost of analysis is accomplished by the proposed algorithm using reasonably less number of incremental loads. Finally, it is demonstrated that the proposed procedure and spline׳s method require considerably less number of iterations to reach the sufficient accuracy.

This paper presents a study on the compressive and flexural strength of engineered cementitious composite (ECC) cubes and slabs, reinforced with various polymer fibres. The type of fibre, fibre content and aspect ratio were the parameters considered in this study. For all types of fibre, the compressive strength of the ECC decreased as the reinforcing index increased. For the ECC polypropylene fibre (PP) slabs, the first crack strength significantly decreased with an increase in the fibre content. For the ECC polyethylene fibre (PE) slabs, the first crack strength decreased as the reinforcing index increased. For the ECC PE slabs, the usage of PE 1600D fibres showed a substantial increase in flexural strength due to their higher tensile strength and E modulus. The ECC PP slabs behaved like plane concrete due to the zero value of flexural strength, which was attributed to the weak interfacial bonding with the cement matrix, low tensile strength and E modulus of the PP fibres. The highest ductility was observed for the ECC-PE slabs with the highest recorded deflection values; these values achieved many extended multiple cracks and an extensive area under the load–deflection curve indicating high energy absorption capacity.

This study investigates the variations in the mechanical properties of high-damping rubber bearings HDRBs on the dynamic response of multi-story seismic base-isolated building subjected to bidirectional near-fault ground motions. Variations in the mechanical properties of HDRB due to temperature, aging and scragging recovery are considered. Nonlinear response analyses of a six-story base-isolated building subjected to seven pairs of bidirectional near-fault ground motions with pulse type were conducted using finite element software. The nonlinear force–deformation behavior of isolator is modeled using a bilinear hysteretic curve considering non-deteriorating and deteriorating properties. Results of analyses are compared in terms of bearing displacement, base shear, force–displacement loops, top floor absolute acceleration and story drift. It was observed that the seismic response of base-isolated multi-story building is significantly influenced by the variation in mechanical properties of rubber bearing seismic isolators.

A two-step damage identification approach based on wavelet multi-resolution analysis and genetic algorithm (GA) in beam structures is presented in this paper. The location of the crack is identified in the first step by defining the damage index called relative wavelet packet entropy. Then, the damage severities at the identified locations are assessed in the second step using GA. The wavelet packet component energies for each damage depth used in the first step and the severity evaluation database required for the second step to reveal the relationships between the energies and damage severities are obtained using a multi-resolution wavelet packet transform. The effects of wavelet type and decomposition level on the detection of damage location are examined in beams with various damage scenarios in the presence of different noise levels. To investigate the robustness and accuracy of the proposed method, numerical examples and experimental cases with different damage depths are considered. The results demonstrate that the proposed method performs reasonably well and has great potential in the identification of damage locations and estimation of damage severities.

This paper focuses on the evaluation of the effect of masonry-infilled walls on the seismic response of a four-storey RC school building. Numerical simulation is presented with respect to the building with and without masonry-infilled walls. The simulation employed force-based fibre elements for beams and columns, and a single equivalent diagonal strut to represent the masonry infill. The numerical model was verified through comparison with shake table test results. It was found that the presence of masonry-infilled walls has significant influence on the global response of the structure. Although the displacement of the structure with infilled wall is reduced in the in-plane direction, it was increased in both in-plane and out-of-plane directions when the infilled walls experienced loss in serviceability.

The different stages in the processing of palm oil generate various types of waste by-products, which have to be disposed of appropriately for a cleaner environment and to reduce pollution. In this study, palm oil clinker (POC), one of the by-products of the palm oil mill, was utilized in the production of self-compacting concrete (SCC). SCC has diverse types of structural application due to its own enhanced self-consolidating behaviour. The proportioning of the mixes was based on particle packing, which integrates both aggregate packing and void volume for a mix of aggregates. Combinations of POC and natural aggregate were studied at various substitution levels ranging from 0% to 100% for both fresh and hardened properties. In addition, a few of the results were integrated into sustainability components to evaluate the effectiveness of the concrete both economically and environmentally. It was found that POC aggregate require three times lower energy consumption for preparation compared to conventional aggregate. Overall, POC incorporation showed enhanced structural efficiency with a significant reduction in cost and energy usage. Furthermore, the sustainability of the construction industry can be conserved with the introduction of POC as an alternative source for concreting work.

Wavelet solution techniques have become the focus of interest among researchers in different disciplines of science and technology. In this paper, implementation of two different wavelet basis functions has been comparatively considered for dynamic analysis of structures. For this aim, computational technique is developed by using free scale of simple Haar wavelet, initially. Later, complex and continuous Chebyshev wavelet basis functions are presented to improve the time history analysis of structures. Free-scaled Chebyshev coefficient matrix and operation of integration are derived to directly approximate displacements of the corresponding system. In addition, stability of responses has been investigated for the proposed algorithm of discrete Haar wavelet compared against continuous Chebyshev wavelet. To demonstrate the validity of the wavelet-based algorithms, aforesaid schemes have been extended to the linear and nonlinear structural dynamics. The effectiveness of free-scaled Chebyshev wavelet has been compared with simple Haar wavelet and two common integration methods. It is deduced that either indirect method proposed for discrete Haar wavelet or direct approach for continuous Chebyshev wavelet is unconditionally stable. Finally, it is concluded that numerical solution is highly benefited by the least computation time involved and high accuracy of response, particularly using low scale of complex Chebyshev wavelet.

This paper investigates the effects of polyvinyl alcohol (PVA) fibers on the toughness, compressive and flexural strength of engineered cementitious composite (ECC) cubes and slabs. The key parameter discussed in this study is the reinforcing index. To evaluate the strain-hardening behavior of ECC with different PVA fiber contents, tests were conducted in direct tension. Flexural toughness was also evaluated following ASTM C 1018 procedure and post-cracking strength technique (PCSm). Results showed that the compressive strength decreases as the reinforcing index increases in a nonlinear trend. By increasing the reinforcing index, the first crack load decreases and ultimate strength slightly increases. Furthermore, a significant increase in the first crack strength was obtained by an excess value 1000 of the reinforcing index. There is a significant increase in the deflection at ultimate load and the deflection at failure as the reinforcing index increases in a linear manner. The strain-hardening and multiple cracking behavior were observed for slabs with reinforcing indices higher than 316 whereas the softening behavior was observed for lesser values. The ECC PVA slabs did not attain the desired ductility due to the rupture of PVA fibers. A significant increase has occurred to the toughness indices I20, I30 and I40 with the increase in reinforcing index. Moreover, the indices exceed the limitations considered. A new definition as an extension to the definition given in ASTM C 1018 was proposed for ECC PVA material according to the observed results. All the residual strength factors increased as the reinforcing index increases which indicates a higher amount of strength retained. The PCS60 values increased with increase in the reinforcing indices. Thus, the increase in PCS60 values indicates higher flexural performance, better ductility and energy absorption capacity for slabs.

Palm oil clinker (POC) is a waste material generated in large quantities from the palm oil industry. POC, when crushed, possesses the potential to serve as an aggregate for concrete production. Experimental investigation on the engineering properties of concrete incorporating POC as aggregate and filler material was carried out in this study. POC was partially and fully used to replace natural coarse aggregate. The volumetric replacements used were 0%, 20%, 40%, 60%, 80%, and 100%. POC, being highly porous, negatively affected the fresh and hardened concrete properties. Therefore, the particle-packing (PP) method was adopted to measure the surface and inner voids of POC coarse aggregate in the mixtures at different substitution levels. In order to enhance the engineering properties of the POC concrete, palm oil clinker powder (POCP) was used as a filler material to fill up and coat the surface voids of POC coarse, while the rest of the mix constituents were left as the same. Fresh and hardened properties of the POC concrete with and without coating were determined, and the results were compared with the control concrete. The results revealed that coating the surface voids of POC coarse with POCP significantly improved the engineering properties as well as the durability performance of the POC concrete. Furthermore, using POC as an aggregate and filler material may reduce the continuous exploitation of aggregates from primary sources. Also, this approach offers an environmental friendly solution to the ongoing waste problems associated with palm oil waste material.

Classical damage detection methods such as visual inspections have many limitations, i.e. time consuming procedure, costly process and ineffective for large and complex structural systems. To overcome these difficulties, a data mining-based damage identification approach is developed in this study. First four natural frequencies which obtained from the experimental modal analysis of a slab-on-girder bridge structure are used as an input database. The laboratory work is carried out through single-type and multiple-type damage scenarios. The applicability of machine learning, artificial intelligence and statistical data mining techniques are here examined using Support Vector Machine (SVM), Artificial Neural Network (ANN) and Classification and Regression Tree (CART) to predict the model behavior and damage severity. Then, a hybrid algorithm is proposed in the deployment step of Cross Industry Standard Process for Data Mining (CRISP-DM) model. According to the obtained results, the hybrid algorithm performs a better accuracy in compare to ANN technique itself.

The type of frame system, materials, and power consumption used for the construction of new buildings cause environmental issues because of the production of carbon dioxide (CO2) emissions. Therefore, a new type of sustainable precast concrete structural system called SMART frame has been introduced to reduce the CO2 emissions during the construction of buildings. To determine the effectiveness of the CO2 emission reduction based on the new SMART frame, a similar frame configuration based on reinforced concrete (RC) was used. The SMART and RC building frames consisted of 12 storeys with similar floor areas and were designed under similar conditions. The CO2 emissions based on the material resources and construction methods used for the two building models were analysed. Additionally, the power consumption associated with the use of electricity and fuels for the devices and equipment was considered in the analysis of the total CO2 emissions. The total CO2 emissions of the SMART and RC frame buildings in kilograms (kg) per square meter (m2) are 455.94 and 516.12 kg CO2/m2, respectively. Thus, the total amount of CO2 emission reduction achieved in this study is 60.18 kg CO2/m2. In terms of the individual effects of materials and power consumption, the SMART building has a larger contribution, accounting for a 12.42% and 8.12% decrease in the CO2 emissions, respectively, compared with the RC building. Overall, based on the materials and power consumption used during the construction stage of the SMART frame building, the total CO2 emissions decreased by 11.66% compared with the RC building. Therefore, the SMART frame can be adopted as a sustainable frame alternative to the RC frame system.

Precast construction of structural buildings requires connection techniques that can shorten the process using only simple on-site activities while still guaranteeing adequate strength, energy dissipation, stiffness, and ductility. The construction methods should decrease the use of formwork and temporary bracing to save time and costs. In this study, innovative hybrid connections using steel tubes, steel plates, and steel couplers to join beams and columns were proposed and tested under reversed cyclic loading. Five half-scale samples of the hybrid precast joints, including the monolithic and precast joints, were examined to evaluate the seismic performance of the connections. The hybrid connections showed better performance in terms of load, displacement, drift ratio, ductility, strength, stiffness, and energy dissipation compared to a monolithic connection. The drift ratio, moment capacity, strength, and total cumulative energy dissipation of the hybrid connections were higher by 12.5–50.0%, 34.68–59.57%, 35.0–60.0%, and 50.99–331.32%, respectively, when compared with a monolithic connection. The failure modes of the hybrid connections were governed by yielding steel reinforcement, yielding steel plate, and flexural failure, with less extensive damage compared to the monolithic joint. The hybrid connections were effective in shifting the plastic hinges to outside the connection zone. Therefore, the hybrid connections can be used in high seismic zones because the superior performance results meet the requirements of the seismic codes.

Landslide is considered as one of the major natural hazards that cause enormous social and economic losses. Some techniques have been introduced to monitor the stability of slopes, such as the global positioning system (GPS), the geographic information system (GIS), aerial photography, and inclinometers. Each one of these offers advantages against others, but at the same time also possesses different limitations. Acoustic emission (AE) has recently been recognized as one of the feasible techniques to monitor soil slope. This article addresses issues involved in application of AE techniques for soil slope monitoring. If it is properly instrumented, AE could provide effective solutions for detecting early activities related to landslide development and giving early warning to such failures.

The consumption of waste materials in self-compacting concrete (SCC) in the construction industry will not only help to conserve the natural resources but also promote sustainability in preserving the environment. Palm oil clinker (POC) is a waste by-product from the incineration process of oil palm shells and fibres. They are porous and lightweight in nature, which makes them suitable for use as a lightweight aggregate (LWA). In this study, a new procedure was employed to obtain the mix design based on the particle packing (PP) concept to ensure the fresh and hardened properties of SCC are achieved. The actual packing level of aggregate and paste volume is integrated into the proportioning method to obtain the final mix design. The proposed procedure was verified by evaluating the SCC formed for self-compactability and mechanical properties. Based on the overall performance of fresh and hardened properties, it can be deduced that the procedure satisfied the requirements for SCC. The satisfactory results indicate that the mix design can be employed not only for POC but also for a variety of combinations of aggregate.

The contribution to global CO2 emissions from concrete production is increasing. In this paper, the effect of concrete mix constituents on the properties of concrete and CO2 emissions was investigated. The tested materials used 47 mixtures, consisting of ordinary Portland cement (OPC) type I, coarse aggregate, river sand and chemical admixtures. Response surface methodology (RSM) and particle swarm optimisation (PSO) algorithms were employed to evaluate the mix constituents at different levels simultaneously. Quadratic and line models were produced to fit the experimental results. Based on these models, the concrete mixture necessary to achieve optimum engineering properties was found using RSM and PSO. The resulting mixture required to obtain the desired mechanical properties for concrete was 1.10-2.00 fine aggregate/cement, 1.90-2.90 coarse aggregate/cement, 0.30-0.4 water/cement, and 0.01-0.013 chemical admixtures/cement. Both methods had over 94% accuracy, compared to the experimental results. Finally, by employing RSM and PSO methods, the number of experimental mixtures tested could be reduced, saving time and money, as well as decreasing CO2 emissions.