Reinforced concrete structures constructed in coastal areas in Indonesia often suffer damage before reaching their intended service life, with steel reinforcement corrosion being a major contributing ...factor. This study aims to investigate the use of concrete structures produced with simple methods and inadequate supervision in coastal regions. Reinforced concrete structures near the coast are susceptible to carbonation due to marine environmental factors, leading to reinforcement corrosion. The study was conducted on the Dande Dandere Market building, Tanakeke Island, Takalar Regency, South Sulawesi. The research method employed quantitative techniques, including surveys and structural testing. Visual inspections were conducted to identify the types of damage present in the building and estimate their causes. Structural testing involved both destructive and non-destructive tests. Concrete compressive strength testing was also conducted to assess the concrete sample’s compressive strength, along with carbonation testing to determine the acidity level of concrete due to the intrusion of salt compounds or carbonation formed within the concrete mass. The research findings indicate structural degradation in the market’s construction, occurring more rapidly than the intended lifespan of the building. Signs of structural degradation in the reinforced concrete construction include spalling of concrete cover on beams, supporting columns, and cantileverslabs, as well as degraded reinforcement, with an average reduction in steel weight of 62.70% over six years, and an average weight loss of 0.103 grams per day. Therefore, efforts are needed to optimize the structural quality of the building through comprehensive repairs, starting from the foundation. However, for cost-efficient alternatives, it is recommended to use timber structural materials for new market construction. The use of timber in coastal buildings, which are vulnerable to marine influences, is more feasible as the presence of saltwater can inhibit wood decay caused by microorganisms.
Adhesive joints have been known and applied for timber structures for decades. Hybrid joints with glued-in rods are nowadays successfully used for both constructing new and strengthening existing ...timber structures. Since the 1980s the research and development of timber joints with bonded-in rods have been going on, however agreement regarding design criteria for these connections has not been reached. Today, connections with glued-in rods are not included in the European design code. Thus, it is desired to gather the current state of knowledge to enable application in practice of the existing and documented knowledge and experience. This paper summarizes practical and theoretical approaches from research done regarding joints with glued-in steel rods mostly in Europe and published in English, German or Swedish. The review considers manufacturing methods, mechanisms and parameters governing the performance and strength of the joints, theoretical approaches and existing design recommendations.
Despite the growing popularity of wood and wood-based products in the construction industry, there has been insufficient focus on assessing the condition, preservation, and potential reuse of ...existing timber. While numerous standards evaluate the quality of freshly sawn timber, there is currently no standardized system for assessing the strength properties of aged and reused timber. The lack of these guidelines is also one of the reasons the results obtained in numerous research are often fluctuating, and we cannot draw clear conclusions. The matter is further complicated by the lack of data on old in-situ wood and its exploitation, which would help to evaluate its condition. Consequently, there is a real practical need to assess the condition of old timber to avoid unnecessary demolition and the loss of valuable and structurally sound building material. What sets this study apart from others is that, in addition to destructive testing, the 4-point non-destructive (ND) bending tests were conducted on all four faces of test specimens. This provided an opportunity to assess the wood visually and then find connections to associate external characteristics with real properties. This methodology aimed to determine whether it is feasible to visually assess the most practical way to use wooden elements in construction. If this question arises, which face of the beam would be better suited for the tension side and which for the compression side? The old timber used in testing originated from an old library building located on Vaksali Street, Tartu, Estonia and is estimated to be about 120 years old. This paper investigates and compares the collected data with a Nordic standard for grading fresh-sawn timber and two established Italian standards for visually assessing aged timber. This comparison contributes to developing a standardized framework for future visual assessments. ND and destructive four-point bending tests were performed to validate and find appropriate visual characteristics to determine the strength and stiffness of the timber elements. The primary goals of this study were first to compare the results obtained from existing ND methods with actual results and secondly to provide guidelines for better visual grading of wood in the future, based on Nordic Standard INSTA 142 (2010) and Italian standards UNI 11119 (2004) and UNI 11035 (2010) Contrary to previous research conclusions, the visual assessment results yielded unexpected outcomes. The results show that the grading standards significantly underestimated the real strength of the wood, and even more, none of the visual assessments overestimated the real strength of the specimens. Therefore, based on prior research and the findings derived from this study, there is evident a substantial potential for extensive development and optimization within this field.
Abstract
Scots pine (Pinus sylvestris L.) and larch (Larix spp.) are two species that could contribute to diversifying Ireland’s timber supply. However, there is little knowledge about their ...properties as well as their variation with age. The aim of this study is to investigate the structural properties (modulus of elasticity, strength and density) of Irish-grown Scots pine and larch and the effect of cambial age on timber grading. Structural-sized pieces were used for this purpose, and the timber properties, knots and ring width were measured on 158 and 250 pieces of Scots pine and larch, respectively. Characteristic values of the properties and indicative yields for different strength classes were calculated. The age effect was assessed using an empirical approach, and a novel modelling approach that disaggregates the timber properties at the annual growth ring level. Yields above 90 per cent of C20 were achieved for Scots pine, whereas larch achieved a 100 per cent yield of C24 strength class. The effect of cambial age in the grading properties indicated that older boards increased the characteristic values of a timber population. In Scots pine, the empirical approach showed that the yields increased by up to 26 per cent when using pieces up to 50 years old compared with pieces up to 30 years old. In larch, the use of pieces up to 40 years old increased the yields by up to 16 per cent compared with using pieces up to 30 years old. The results of the modelling approach were consistent with the values obtained in the empirical analysis and can help to make informed decisions regarding rotation lengths for the production of structural timber. Our results found that cambial ages of 40 years in Scots pine produce high yields of structural timber, whereas 30 years are enough for larch.
•The twist of the laminated of Eucalyptus grandis appears to be greatly restrained.•A material reduction factor φM of 0.77 can be utilised.•Lamination results in a higher structural grade yield of ...material.•Young engineered Eucalyptus grandis is a promising option for structural timber.
Only 1% of South Africa’s total land area is used for forestry with 51% of that being used for Pinus and 40% for Eucalyptus species. A shortage of adequate structural sawn timber has been forecast where Pinus species is the predominant raw structural material and Eucalyptus is mainly used for pulp production. Young, engineered Eucalyptus grandis has been proposed as an alternative resource to mitigate the shortage of structural timber. The objectives of this study are to determine the material resistance properties and material resistance reduction factors of young, Eucalyptus grandis timber that has been finger-jointed in the green, unseasoned state and (a) is face laminated in the green state and (b) is left as a standard non-laminated set. Both groups were dried before destructive bending tests were performed. The defect development of both sets was recorded. The face lamination process did not reduce the variation in strength results to a significant extent but significantly lower grade-reducing defects, such as twist, checks and splits, were recorded for the laminated set. This results in a higher structural grade yield of material with a better visual appearance due to limited defects, thus producing a more valuable product. Additionally, based on reliability theory, a material reduction factor of 0.77 is proposed in this study in contrast to the current factor of 0.68 stipulated by the national code. This advantage, coupled with the higher structural grade achieved and the shorter rotation age than for Pinus species, make the young, green finger-jointed and face laminated Eucalyptus grandis product a promising option for structural timber use in South Africa.
Pine timber of Polish origin intended for structural purposes is characterized by significant variability in the quality parameters. Technological suitability determined on the basis of relevant ...international classifications is based on the assessment of both selected mechanical and physical properties of wood. Moreover, the description of visual properties is also a valuable indicator regarding defect distribution. In the group of quality features playing a crucial role in the classification of sawn timber, there are knots, disruptions of grains, cracks, etc. Thus, the aim of the research was to determine the correlation between the presence of selected defects and the strength properties of individual timber pieces. This type of study is based on a nondestructive test method that allows for high optimization of sawn materials processing. In the case of sawn timber of Polish origin, the modulus of elasticity (
) determined using the sonic test is commonly used as a criterion. The research material was harvested from southern Poland. The results of the conducted studies confirmed a correlation between an increasing occurrence of particular types of defects and the results of
. Furthermore, as a result of the performed investigations, no significant effect of narrow surface cracks on strength properties was observed.
With the rapidly growing interest in using structural timber, a need exists to inspect and assess these structures using non-destructive testing (NDT). This review article summarizes NDT methods for ...wood inspection. After an overview of the most important NDT methods currently used, a detailed review of Ground Penetrating Radar (GPR) and Ultrasonic Testing (UST) is presented. These two techniques can be applied in situ and produce useful visual representations for quantitative assessments and damage detection. With its commercial availability and portability, GPR can help rapidly identify critical features such as moisture, voids, and metal connectors in wood structures. UST, which effectively detects deep cracks, delaminations, and variations in ultrasonic wave velocity related to moisture content, complements GPR's capabilities. The non-destructive nature of both techniques preserves the structural integrity of timber, enabling thorough assessments without compromising integrity and durability. Techniques such as the Synthetic Aperture Focusing Technique (SAFT) and Total Focusing Method (TFM) allow for reconstructing images that an inspector can readily interpret for quantitative assessment. The development of new sensors, instruments, and analysis techniques has continued to improve the application of GPR and UST on wood. However, due to the hon-homogeneous anisotropic properties of this complex material, challenges remain to quantify defects and characterize inclusions reliably and accurately. By integrating advanced imaging algorithms that consider the material's complex properties, combining measurements with simulations, and employing machine learning techniques, the implementation and application of GPR and UST imaging and damage detection for wood structures can be further advanced.
•Review on compression perp. to grain in timber, CLT and stress dispersion models.•Experiments on CLT in compression perp. to grain analyzing main parameters.•Van der Put’s stress dispersion model ...adapted for parallel and perp. to grain.•Provisions for testing, evaluation and generic design approach for timber.
Timber exposed to compression perpendicular to grain stresses is of concern in all timber constructions. The challenge is the high diversity of possible load configurations, which mandates for a generic approach with basic properties and case individual adaptations of resistance and stiffness. As the consequences of exceeding the allowed stresses are relatively small, there has been a lively debate on whether compression perpendicular to grain should be treated as an ultimate or better as a serviceability limit state. This debate takes also its place in the currently ongoing revision of Eurocode 5 (EC 5), the European design code for timber structures. In the course of this revision regulations for structural timber products not currently anchored in EC 5, in particular for cross laminated timber (CLT), are now being sought. The product CLT is so far lacking in specifications for the testing, basic properties and design. In awareness of the necessity for generally applicable and reliable design approaches, I aim to present the state-of-the-art on compression perpendicular to grain/plane by focusing on the design, i.e. stress dispersion models, and cross laminated timber. In addition, I present the main data and findings from a comprehensive test campaign and adapt van der Put’s stress dispersion model for stress dispersion in directions parallel and perpendicular to grain. This new approach allows an explanation of the influences caused by (i) contact area, (ii) load configurations, (iii) support conditions, (iv) layup and thickness of the CLT element, and (v) clear edge distances and clear spacing. The same approach is applicable for both strength and modulus of elasticity. The necessity to consider the orthogonal layup emerged in the case of CLT. I conclude with recommendations for testing and evaluation, propose basic properties and regulations for the main influencing parameters as also a generic design approach generally applicable for all linear and planar, unidirectional and orthogonal laminated structural timber products.
The typical variability of wood properties, higher than for other construction materials, requires a thorough knowledge of its mechanical performance. To make the use of wooden structural products ...safe and at the same time efficient, a proven methodology for the selection of the raw material is also crucial. As a general rule, the initial sampling is of vital importance to develop effective strength grading processes, but it is rarely verified with additional samples, besides those already included during the development of the grading procedure itself. Here, a new source of sawn timber was collected to verify the original sampling and to validate the visual and machine strength grading early developed for Italian beech. The new pieces were graded, destructively tested and the characteristic values of the graded material were calculated. The dispersion of the new data was found to be entirely included in that of the original data, proving an effective sampling of the resource variability. The correlations between properties were very similar comparing the original and the new sample, with the exception of the correlations between the dynamic modulus of elasticity and both bending strength and stiffness, which were lower in the new sample. The characteristic values of the graded new material were generally higher than the characteristics values of the corresponding strength classes as tabled in the technical standard. Only for one grade in the machine grading the strength reached 98.9% the class value, anyhow above the 90% required by the procedure of the checking of existing settings in a particular location, as provided by the related standard. In conclusion, the earlier development of the strength grading of Italian beech confirmed to be correct and safe.
Threaded-dowel type timber joints with free ends and with nut-washer end fixings were experimentally investigated, modifying the orientation of the timber beams and the evolution in the deformation ...of their fibres as the structure was loaded, with the objective of quantifying their contribution to the strength in relation to displacement. The work is based on an analysis of the equations for the dimensioning of dowels, compiling the original models developed by Johansen in comparison with the superimposition extensions of Eurocode 5. This provides the basis for carrying out the experimental tests to compare the load capacity established in the dimensioning of structures with the experimental results. This work focuses on dowels-type joints that fail in plastic mode, which improves the distribution of stresses and optimizes the resistant capacity of the joint while analysing the crushing regions in the contact areas of the timber dowel which contain the dowel and redefine the angle of the hinge joint in successive flat planes perpendicular to the axis of the hole where the dowel is housed, which allows analysing the dominant stresses related to the repositioning of the timber fibres exposed to crushing. The tests with nut-washer fastening show a behaviour that notably improves the resistant capacity when the degree of displacement increases. This research shows how the capacity of the structural joints is linked to the effects of crushing, provoking a reorientation of the fibres. This work raises the need to study in detail the resistance of the structural joint, limiting the displacement, when comparing the analytical results against the displacement curves of the experimental tests. It can be seen that increases in the angle of orientation of the fibre of the beams are penalized by the analytical equations with load capacity losses greater than 10% for fibre angles located at 90°, however the tests show an improvement in the progressive resistance capacity with the displacement. The load capacity in the joint improves by 7% and 11% for fibre orientations at 45° and 90°, if no fixing is established at the ends of the joint. These values reach improvements of 13% and 28% when there is fixing at the ends of the dowel.
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