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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.

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.

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 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)

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 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.

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.

This paper presents a study to determine the effectiveness of Carbon Fiber Reinforced Polymer (CFRP) sheets as a flexural repair system for Reinforced Concrete (RC) beams. The effectiveness of these sheets is ascertained by monitoring the flexural stiffness recovery. Experimental work is conducted on scaled beams where four beams are used as the datum. The first beam is without CFRP sheets, the second is a repaired beam after pre-damaged under design load limit, whilst the third is a repaired beam after pre-damaged under steel yield load limit, and the fourth is a repaired beam after pre-damaged under ultimate load. Comparisons are made based on the flexural stiffness recovery, crack patterns, load capacity, and failure modes of the beams. The study validates the ability of the flexural stiffness change in order to monitor the effect of the damage as well as the effectiveness of the repair on stiffness recovery. The results prove the effectiveness of the CFRP sheets as a repair technique which increases the flexural stiffness and the ultimate load capacity whatever the pre-repair damage levels. In addition, this study indicates the ability of re-repairing the beams in the case of CFRP debonding. The failure modes are controlled by the pre-repair damage flexural crack wherein it causes the CFRP debonding.

In this investigation 12 mortar mixes including three groups were prepared using binder contents 380 and 500 kg/m 3 . All the specimens were cured after casting and demoulding in curing regimes, i.e. at room temperature (ac) and in water (wc). The highest strength was obtained for cement–slag mortars 380-wc at later ages as 80 MPa. For all groups of mortars, there could rarely be strength loss at later ages. It was observed that in duration of 3–7 days, wc is the optimum for all groups of mortars with exception of cement mortar 500 and slag mortar 500. In duration of 28–90 days, wc is also the optimum for three groups of mortars with exception of cement mortar 500. It was revealed that an exponential relationship exists between the strengths obtained in air and water curing conditions for each group of mortar, i.e. with and without using ground granulated blast furnace slag. It was proved that higher strengths could be obtained using lower binders’ contents for cement and cement–slag mortars provided the specimens were cured in water. This is a new finding having importance from economic and environmental viewpoints; meaning that for producing higher strengths it is not a necessity to use more binders. It was found that increase in level of cement and slag makes the mortars more sensitive to air curing conditions.

Curing techniques and curing duration have crucial effects on the strength and other mechanical properties of mortars. Proper curing can protect against moisture loss from fresh mixes. The objective of this experimental work is to examine the compressive strength of ordinary Portland cement mortars (OMs) under various curing regimes and cement fineness. Six different curing methods including water, air, water heated, oven heated, air–water, and water–air were applied to the specimens and also six groups of mortars were used. The results showed that the highest and lowest compressive strengths are attributed to the specimens of OPC mortar water cured using grounded OPC for duration of 6 h (OM–G6–wc) and OPC mortar air cured under room temperature with oven heated after demoulding of the specimens at 60 °C for duration of 20 h (OM–OH–ac), respectively. The maximum levels obtained of compressive strengths at 7, 28, and 90 days are 57.5, 70.3, and 76.0 MPa, respectively.

This paper compares three methods for activation of OPC-slag mortars (OSM): (1) prolonged grinding of binders (mechanical method), (2) elevated temperature curing of mortars (thermal method), and (3) use of chemical activators such as NaOH, KOH, and Na2SiO3, 9.35H2O (chemical method). The proper reactivity of OSM was evaluated using a mixture of 50% OPC and 50% slag. Early and ultimate strengths were compared. All three activation methods accelerated both the slag reaction and strength development rates. However, the chemical method did not show a significant effect on the ultimate strength, while thermal activation increased the early strength by 3 days. Mechanical activation increased the early strengths of the mortar significantly, but about 6% strength loss occurred in the ultimate strength. Although, the application of mechanical and thermal activation methods needs extra equipment and energy, due to more significant of strength improvement; based on current test results, it can be said that mechanical activation is the most efficient and feasible method for the activation of OSMs.

This study presents the effect of incorporating local calcined kaolin on the engineering properties and durability of concrete with water/binder ratios in the range of 0·40–0·60. Blended mixtures with cement replacement of 5, 10, 15 and 20% were designed with a target slump of 150 ± 25 mm. From this investigation, it was found that a 10% replacement level was the optimum level in terms of compressive strength. Beyond 10% replacement levels, the strength was decreased but remained higher than the control mixtures with the exception of water/binder ratio of 0·60. With respect to the durability test, the initial surface absorption at 10 min (ISA-10), the sorptivity and the water absorption were enhanced with higher replacement level regardless of water/binder ratio. A linear equation was developed to determine the superplasticiser dosage for a desired workability based on the obtained results. This investigation has shown that the local kaolin has a potential to be incorporated as blended cement as it improves the durability/permeability and compressive strength in comparison with ordinary Portland cement mixtures.

Although the use of slag has many benefits, its low hydration at early stages causes the strength to be low. Hence, the uses of slag are restricted, even before it needs to be activated. In this investigation, a chemical method was used to activate the ordinary Portland cement-slag mortars (OSM). 37 OSM were used, 4 of them as control. All mix designs were made by W / B = 0.33, S / B = 2.25, and with 0%, 30%, 40%, 50%, and 60% levels of slag. The activators; sodium hydroxide, potassium hydroxide, and sodium silicate have been used. Whenever the activators were used alone, the highest effect was obtained by sodium silicate and the lowest for sodium hydroxide. It was determined that the effects of the combined activators are better than that of an individual one. It was observed that strength loss for some mixes, at long ages, is determined by some factors, such as level of slag used, type and dosage of alkali activators, and curing regimes.

This study investigates the engineering performance and CO2 footprint of mortar mixers by replacing Portland cement with 10%, 20%, 40% and 60% fly ash, a common industrial waste material. Samples of self-compacting mortar (SCM) were prepared with four different water/binder ratios and varying dosages of superplasticizer to give three ranges of workability, i.e., normal, high and self-compacting mortar mix. The engineering performance was assessed in term of compressive strength after designated curing periods for all mixes. CO2 footprint was the environmental impact indicator of each production stage. The optimum mix obtained was at 10% replacement rate for all mixes. Total production emission reduced by 56% when the fly ash replacement rate increased from 0% to 60% (maximum). This is translated to a reduction of 80% in eco-points (assuming that the energy consumption rate of production with 0% fly ash is at 100%). Such re-utilization is encouraged since it is able to reduce possible soil toxicity due to sulfur leaching by 5% to 27% and landfill area by 15% to 91% on average.

The agricultural industry in Malaysia has grown rapidly over the years. Palm oil clinker (POC) is a byproduct obtained from the palm oil industry. Its lightweight properties allows for its utilization as an aggregate, while in powder form as a filler material in concrete. POC specimens obtained throughout each state in Malaysia were investigated to evaluate the physical, chemical, and microstructure characteristics. Variations between each state were determined and their possible contributory factors were assessed. POC were incorporated as a replacement material for aggregates and their engineering characteristics were ascertained. Almost 7% of density was reduced with the introduction of POC as aggregates. A sustainability assessment was made through greenhouse gas emission (GHG) and cost factor analyses to determine the contribution of the addition of POC to the construction industry. Addition of POC helps to lower the GHG emission by 9.6% compared to control specimens. By channeling this waste into the construction industry, an efficient waste-management system can be promoted, thus, creating a cleaner environment. This study is also expected to offer some guides and directions for upcoming research works on the incorporation of POC.

This paper presents a wavelet-based scheme for dynamic analysis of 2-dimensional (2D) frames. In the proposed approach, free-scaled wavelet functions are developed for Multi-Degrees-of-Freedom (MDOF) structures, particularly, complex Chebyshev and simple Haar wavelets are implemented. A simple step-by-step and explicit algorithm is presented to calculate the time history response of 2D frames. The validity of the proposed procedure is demonstrated with two examples compared with several common numerical integration procedures such as family ofNewmark-β, Wilson-θ and central difference method. Finally, it is shown that dynamic analysis of 2D frames is optimally accomplished by lesser computational time and high accuracy of results.

This paper presents a wavelet-based genetic algorithm strategy for optimal sensor placement (OSP) effective for time-domain structural identification. Initially, the GA-based fitness evaluation is significantly improved by using adaptive wavelet functions. Later, a multi-species decimal GA coding system is modified to be suitable for an efficient search around the local optima. In this regard, a local operation of mutation is introduced in addition with regeneration and reintroduction operators. It is concluded that different characteristics of applied force influence the features of structural responses, and therefore the accuracy of time-domain structural identification is directly affected. Thus, the reliable OSP strategy prior to the time-domain identification will be achieved by those methods dealing with minimizing the distance of simulated responses for the entire system and condensed system considering the force effects. The numerical and experimental verification on the effectiveness of the proposed strategy demonstrates the considerably high computational performance of the proposed OSP strategy, in terms of computational cost and the accuracy of identification. It is deduced that the robustness of the proposed OSP algorithm lies in the precise and fast fitness evaluation at larger sampling rates which result in the optimum evaluation of the GA-based exploration and exploitation phases towards the global optimum solution.

Civil structures are usually prone to damage during their service life and it leads them to loss their serviceability and safety. Thus, damage assessment can guarantee the integrity of structures. As a result, a structural damage detection approach including two main components, a set of accelerometers to record the response data and a data mining (DM) procedure, is widely used to extract the information on the structural health condition. In the last decades, DM has provided numerous solutions to structural health monitoring (SHM) problems as an all-inclusive technique due to its powerful computational ability. This paper presents the first attempt to illustrate the data mining techniques (DMTs) applications in SHM through an intensive review of those articles dealing with the use of DMTs aimed for classification-, prediction- and optimization-based data mining methods. According to this categorization, applications of DMTs with respect to SHM research area are classified and it is concluded that, applications of DMTs in the SHM domain have increasingly been implemented, in the last decade and the most popular techniques in the area were artificial neural network (ANN), principal component analysis (PCA) and genetic algorithm (GA), respectively.