Assessing structural damages of a heritage building

This paper presents an intensive structural survey work on an industrial heritage structure. This study identified the decay mechanism and material characteristics of the historic structure, including material homogeneity, material strength, structural failures with crack pattern, and deteriorated surface. The damages in the building include decay in timber and stones, dampness problem and incompatible structural assemblage. The lack of a long-term maintenance is one of the potential causes which aggravate the decay mechanism. The findings permitted to appraise the structural safety and to depict some recommendations for better treatment of the structural cracks to restore this industrial heritage structure. These proposals would be useful in the conservation management plan of the city

Investigating the deterioration of an industrial heritage structure

Conservation and rehabilitation of heritage structures has turned into a prime concern in historically enriched countries, especially in developed societies. Modern technologically advanced societies often wish to keep and maintain the remains of architectural heritage sites and pass the essence of these tangible and intangible cultural values to future generations. The present study introduces a historical industrial structure in Guimarães, Portugal which was once renowned as part of the leather industry but has now been dilapidated for many years. As part of the city authority’s plan to regenerate the whole town, this industrial heritage structure needs to be rehabilitated. This study presents an intensive structural survey with conventional non-destructive tests (NDT). Visual survey was used to attempt to identify problems in the structure and their possible decay mechanisms. Damages to the building include the decay of timber and stones, dampness problems and incompatible structural assemblage. The lack of long-term maintenance is one of the potential causes which has aggravated decay. NDTs were utilised to characterise the basic mechanical properties of the deteriorated timber elements. The findings allowed the safety of this industrial heritage structure to be appraised which could be beneficial for the conservation management plan of this city

Assessment of distillate water quality parameters produced by solar still for potable usage

In this study, a few field experiments were conducted on a simple solar still and water quality analyses were done in laboratory to check the contaminants removal efficiency from raw water samples. A few water quality parameters such as pH, redox, electrical conductivity (EC), salinity, total dissolved solids (TDS), Escherichia coli and arsenic for the feed (before distillation) and product water (after distillation by a solar still) were obtained. A wide range of water samples (e.g. seawater, pond water, and arsenic contaminated groundwater) were collected from various locations in Malaysia and Bangladesh. A few synthetic saline water samples (e.g. 1, 2, 3 and 5% salt) were also prepared. The values of pH (6.5-7.5), redox (100-200 mV), EC (< 750 mS/cm) of the product water were found within the standard ranges. The average removal efficiencies of more than 24 and 99% were obtained from repetitive tests run on salinity and arsenic, respectively. The still was also successful in removing pathogenic bacteria by more than 80%. These obtained parameters of the product water were then compared with various drinking water standards and found that most of the values obtained were within the acceptable ranges provided by the standards. Finally, it is concluded that the solar still is able to produce potable water and can be installed to remove the water scarcity in coastal and arid regions

Brick manufacturing practice in Bangladesh: a review of energy efficacy and air pollution scenarios

Building structures and major construction works are booming in the urban areas of Bangladesh to keep up the rapid urbanization rate. Brick is an essential construction material for its building industries. To meet the need of construction, brickfields are growing sporadically here and there at the fringe zones and within the urban regions. Eventually, brickfields are producing major environmental pollutants. This paper highlights existing technologies of brick manufacturing as well as their emission which exceeds the tolerable limit and puts a threat to the environment. Treatise is also portrayed regarding techniques which could help minimizing the drawback of existing brick kiln technologies. Vertical Shaft Brick kiln might be an altern ative solution for the small investors in Bangladesh which is energy efficient and can minimize the air pollution to achieve a sustainable environment

Efficient design in building construction with rubber bearing in medium risk seismicity: case study and assessment

Earthquakes pose tremendous threats to life, property and a country's economy, not least due to their capability of destroying buildings and causing enormous structural damage. The hazard from ground excitations should be properly assessed to mitigate their action on building structures. This study is concerned with medium risk seismic regions. Specifically, the heavily populated capital city Dhaka in Bangladesh has been considered. Recent earthquakes that occurred inside and very close to the city have manifested the city's earthquake sources and vulnerability. Micro-seismicity data supports the existence of at least four earthquake source points in and around Dhaka. The effects of the earthquakes on buildings are studied for this region. Rubber base isolation is selected as an innovative option to lessen seismic loads on buildings. Case studies have been carried out for fixed and isolated based multi-storey buildings. Lead rubber bearing and high damping rubber bearing have been designed and incorporated in building bases. Structural response behaviours have been evaluated through static and dynamic analyses. For the probable severe earthquake, rubber bearing isolation can be a suitable alternative as it mitigates seismic effects, reduces structural responses and provides structural and economic benefits

A review of the corrosion behavior of metallic heritage structures and artifacts

Awareness about restoring and preserving historically important structures and artifacts is gradually growing in many parts of the world. These artifacts and structures represent the culture, tradition and past of a nation. They are often also a source of national income through tourist activities. Besides masonry and wood work, metallic forms and relics are a vital part of the heritage which needs to be conserved. Certain metals have been used significantly throughout history in the creation of objects and structures. However, metals are prone to decay over time, particularly decay through corrosion. The basic mechanisms of metal corrosion, the various types of corrosion and existing remedial solutions are reviewed in this paper. The most significant factor affecting metal corrosion was found to be the surrounding environment, especially in marine areas. Different remedial measures can be implemented on corroded metals according to their specific properties. Recommendations for further study are offered at the end of the paper

Strengthening performance of reinforced concrete beam using combined externally bonded and near surface mounted techniques / Kh. Mahfuz Ud Darain

Structural strengthening is a technique to upgrade and improve existing structural systems to carry additional loads and prolong design life. Various structural strengthening techniques are now being used in the construction industry. Among these techniques, the externally bonded reinforcement (EBR) technique is the most common. However, it has a tendency to fail by debonding failure at the plate curtailment location. This is due to interfacial shear stress, which increases with increasing plate thickness. The near surface mounted (NSM) technique is comparatively new and more efficient. Nevertheless, it exhibits premature failure when multiple grooves are used within a narrow cross-sectional width. The aim of this research was to develop a strengthening solution to improve the structural performance of RC beams while avoiding premature failure. To achieve this objective, this study proposed a combination of the EBR and NSM techniques, calling it the combined externally bonded and near surface mounted (CEBNSM) technique. In this study, the performance of RC beams strengthened with the CEBNSM technique were investigated experimentally. An artificial intelligence technique was used to predict the serviceability behavior of these strengthened beams. The finite element method (FEM) was also used to simulate the structural behavior of the strengthened beams. The experimental test matrix consisted of a total of twenty-seven RC beams divided into four groups. Round steel or CFRP bars were used in the NSM grooves for the CEBNSM-B beams, whereas rectangular CFRP strips were inserted into the CEBNSM-S beams. In both cases, CFRP fabric was externally bonded at the tension face of the beam soffit. NSM and EBR strengthened beams were also tested in order to compare results with the CEBNSM technique. Fuzzy logic expert system (FLES) was used as an artificial intelligence (AI) tool to predict the serviceability behavior of the strengthened beams. Incremental static load and variable NSM bar length were the input parameters and the outputs were deflection and crack width of the strengthened beams. Applying expert knowledge using if-then rules, the input and output variables were expressed linguistically as well as in numeric values. FEM was applied to develop a numerical model to verify the experimental results of the strengthened RC beams. The plastic damage behavior of concrete, elasto-plastic behavior of steel reinforcement and material nonlinearity were considered in developing the FEM model. Beams strengthened with NSM CFRP showed greater increment in strength, although they failed prematurely, in contrast to the flexural failure of steel bar NSM beams whose stiffness and cracking behavior were superior as well. For CEBNSM beams, the ultimate capacity increased from 32% to 176%, depending on the variation in strengthening reinforcement ratio. The failure mode, serviceability and stiffness of the beams also improved considerably. The output of the AI models excellently predicted the deflection and crack width of the strengthened beams. In evaluating the FLES prediction model, it was found that the relative error of the predicted deflection and crack width values were within the acceptable limit (5%) and the goodness of fit of the predicted values was close to 1.0. The results simulated by the FEM model satisfactorily agreed with the load-deflection and strain values of the CEBNSM strengthened RC beams. The simulated damage pattern of the beams also matched well with the experimental beams

The Tension-Stiffening Contribution of NSM CFRP to the Behavior of Strengthened RC Beams

Tension stiffening is a characteristic behavior of reinforced concrete (RC) beams which is directly affected by the bond-slip property of steel bar and concrete interfaces. A beam strengthened with a near-surface mounted (NSM) technique would be even more affected by tension stiffening, as the NSM reinforcement also possess a bond-slip property. Yet assessing how much the tension stiffening of NSM contributes to the behavior of RC beams is difficult due to the fact that bond-slip effects cannot be directly incorporated into a strain-based moment-curvature analysis. As such, the tension stiffening is typically incorporated through various empirical formulations, which can require a great deal of testing and calibrations to be done. In this paper a relatively new method, which can be called the mechanics-based segmental approach, is used to directly simulate the tension stiffening effect of NSM reinforcements on RC beams, without the need for empirical formulations to indirectly simulate the tension stiffening. Analysis shows that the tension stiffening of NSM fiber reinforced polymer (FRP) contributes a significant portion to the stiffness and strength of the strengthened RC beam not only during serviceability, but at all load levels

Glass Fiber Reinforced Polymer (GFRP) bars for enhancing the flexural performance of RC beams using Side-NSM technique

Reinforced concrete (RC) structures require strengthening for numerous factors, such as increased load, modification of the structural systems, structural upgrade or errors in the design and construction stages. The side near-surface mounted (SNSM) strengthening technique with glass fiber-reinforced polymer (GFRP) bars is a relatively new emerging technique for enhancing the flexural capacities of existing RC elements. Nine RC rectangular beams were flexurally strengthened with this technique and tested under four-point bending loads until failure. The main goal of this study is to optimize the structural capacity of the RC beams by varying the amount of strengthening reinforcement and bond length. The experimental test results showed that strengthening with SNSM GFRP bars significantly enhanced the flexural responses of the specimens compared with the control specimen. The first cracking and ultimate loads, energy absorption capacities, ductility and stiffness were remarkably enhanced by the SNSM technique. It was also confirmed that the bond length of the strengthened reinforcement greatly influences the energy absorption capacities, ductility and stiffness. The effect of the bond length on these properties is more significant compared to the amount of strengthening reinforcement

Glass Fiber Reinforced Polymer (GFRP) Bars for Enhancing the Flexural Performance of RC Beams Using Side-NSM Technique

Reinforced concrete (RC) structures require strengthening for numerous factors, such as increased load, modification of the structural systems, structural upgrade or errors in the design and construction stages. The side near-surface mounted (SNSM) strengthening technique with glass fiber-reinforced polymer (GFRP) bars is a relatively new emerging technique for enhancing the flexural capacities of existing RC elements. Nine RC rectangular beams were flexurally strengthened with this technique and tested under four-point bending loads until failure. The main goal of this study is to optimize the structural capacity of the RC beams by varying the amount of strengthening reinforcement and bond length. The experimental test results showed that strengthening with SNSM GFRP bars significantly enhanced the flexural responses of the specimens compared with the control specimen. The first cracking and ultimate loads, energy absorption capacities, ductility and stiffness were remarkably enhanced by the SNSM technique. It was also confirmed that the bond length of the strengthened reinforcement greatly influences the energy absorption capacities, ductility and stiffness. The effect of the bond length on these properties is more significant compared to the amount of strengthening reinforcement