Damp Buildings Research Articles

Educational building conditions and the health of users

In order to maintain a healthy learning environment, diagnosis and management of defects in the educational facility are paramount. The preliminary results of the ongoing research reported here seek to identify defects associated with educational buildings and their effects on the health of polytechnic students and staff in Nigeria. A questionnaire survey, including 34 defects based on a post-occupancy evaluation (POE) was used to establish relationships with the health of polytechnic students and staff. Two hundred (200) respondents were randomly selected based on their schools (faculty) within Lagos State Polytechnic. Descriptive and inferential statistics were used for analysis of the collected data. The results of the study indicate that defects such as plumbing and dampness problems, cobwebs and dust, are prominent in the institution. Also the relationship between building conditions (defects) and health problems was established, with the predictors of the health problems. Based on the findings, it is important for designers and managers of facilities within tertiary institutions to develop and implement design and maintenance policies targeted at minimizing the likelihood of plumbing, dampness, electrical, cobweb and dust problems in educational buildings due to the health risks induced by the defects. It is evident that effective maintenance schedules and policies should be put in place to ensure that facilities are not left to decay before replacement.

Anisotropic optical response of optically opaque elastomers with conductive fillers as revealed by terahertz polarization spectroscopy

Elastomers are one of the most important materials in modern society because of the inherent viscoelastic properties due to their cross-linked polymer chains. Their vibration-absorbing and adhesive properties are especially useful and thus utilized in various applications, for example, tires in automobiles and bicycles, seismic dampers in buildings, and seals in a space shuttle. Thus, the nondestructive inspection of their internal states such as the internal deformation is essential in safety. Generally, industrial elastomers include various kinds of additives, such as carbon blacks for reinforcing them. The additives make most of them opaque in a wide spectral range from visible to mid-infrared, resulting in that the nondestructive inspection of the internal deformation is quite difficult. Here, we demonstrate transmission terahertz polarization spectroscopy as a powerful technique for investigating the internal optical anisotropy in optically opaque elastomers with conductive additives, which are transparent only in the terahertz frequency region. The internal deformation can be probed through the polarization changes inside the material due to the anisotropic dielectric response of the conductive additives. Our study about the polarization-dependent terahertz response of elastomers with conductive additives provides novel knowledge for in situ, nondestructive evaluation of their internal deformation.

Development of a method to relate the moisture content of a building material to its water activity.

Subjective indicators of building dampness consistently have been linked to health, but they are, at best, semi-quantitative, and objective and quantitative assessments of dampness are also needed to study dampness-related health effects. Investigators can readily and non-destructively measure the "moisture content" (MC) of building materials with hand-held moisture meters. However, MC does not indicate the amount of the water in a material that is available to microorganisms for growth, that is, the "water activity" (Aw ). Unfortunately, Aw has not been readily measurable in the field and is not relatable to MC unless previously determined experimentally, because for the same moisture meter reading, Aw can differ across materials as well as during moisture adsorption vs desorption. To determine the Aw s that correspond to MC levels, stable air relative humidities were generated in a glove box above saturated, aqueous salt solutions, and the Aw of gypsum board and the relative humidity of the chamber air were tracked until they reached equilibrium. Strong correlations were observed between meter readings and gravimetrically determined MC (r=.91-1.00), among readings with three moisture meters (r=.87-.98), and between meter readings and gypsum board Aw (r=.77-.99).

Hybrid Model for Retrofitting: A Review

Beam-column joint is considered as a crucial zone in moment resisting frames. It is subjected to large forces during an earthquake, due to ground shaking and the response of the building depends on the behavior of the beam-column joint. During analysis, the joints are usually treated as rigid and this fails to consider the effects of various shear forces developed within the joint. So there emerges the need of seismic upgrading owing to structural deterioration, change in functions or increased performance requirements. Damping is one of the commonly adopted methods proposed for achieving optimal performance of the building subjected to seismic actions. In the present study, an economical approach towards the use of dampers in buildings to reduce the seismic effect is studied. A hybrid combination of dampers with steel bracings for retrofitting is studied in this paper. A cost effective hybrid configuration is presented which can simultaneously reduce the seismic effect and the overall cost for retrofitting.

Respiratory symptoms and fractional exhaled nitric oxide (FeNO) among students in Penang, Malaysia in relation to signs of dampness at school and fungal DNA in school dust

Few health studies exist on dampness and mould in schools in the tropics. We studied associations between fraction of exhaled nitric oxide (FeNO), respiratory symptoms and airway infections among students and dampness and fungal DNA in schools in Malaysia. A total of 368 randomly selected students from 32 classrooms in 8 secondary schools in Penang, Malaysia, participated (58% participation rate). Information on current respiratory symptoms and the home environment was collected by a standardised questionnaire. FeNO was measured by NIOX MINO (50ml/min). The classrooms were inspected and dust was collected by vacuuming on special filters and was analysed for five fungal DNA sequences by quantitative PCR. Linear mixed models and 3-level multiple logistic regression (school, classroom, student) were applied adjusting for demographic data and the home environment. Totally 10.3% reported doctor's diagnosed asthma, 15.1% current wheeze, 12.4% current asthma, 37.3% daytime breathlessness, 10.2% nocturnal breathlessness, 38.9% airway infections and 15.5% had pollen or furry pet allergy. The geometric mean of FeNO was 19.9ppb and 45% had elevated FeNO (>20ppb). Boys had higher levels of FeNO. Chinese had less daytime breathlessness than Malay (OR=0.30: p<0.001). Indoor carbon dioxide levels were low (380–720ppm). Dampness was observed in 18% of the classrooms and was associated with respiratory infections (OR=3.70; 95% CI 1.14–12.1) and FeNO (p=0.04). Aspergillus versicolor DNA was detected in 67% of the classrooms. Higher numbers of Aspergillus versicolor DNA in classroom dust were associated with wheeze (p=0.006), current asthma (p=0.002), respiratory infections (p=0.005) and elevated FeNO levels (p=0.02). In conclusion, respiratory symptoms were common among the students and the high FeNO levels indicate ongoing airway inflammation. Building dampness and the mould Aspergillus versicolor in schools in Malaysia can be risk factors for impaired respiratory health among the students.

Galvanic microcells as control agent of indoor microorganisms.

Today, fungicides are part of the basic tool kit for indoor surface maintenance. However, fungi develop resistance to fungicides, which consequently accelerates the evolution of virulence. Fungicides also carry the risk of adverse effects in humans. Galvanic microcells are a new tool for fungal control on indoor surfaces. We used two types of electrodes, Zn and Cu, with two potential anti-fungal mechanisms: the oligodynamic action of the metal ions themselves and the electricidal effect of the current between the electrodes. The size of the inhibition zone is related to the distance between the electrodes. We hypothesized that the unique geometric properties of the observed inhibition zone could be modelled using multi foci curve Cassini ovals. Moreover, the size of the inhibition zone possessed two maximum values, while the shape of the observed inhibition zones correlated with the shape of the electric field strength. The control activity of the galvanic microcells correlated with decreasing water content in building materials. Thus, this acute antifungal system works the best in damp building environments where the risk of fungal contamination is highest.

Ventilation system for drying out buildings after a flood: Influence of the building material

ABSTRACTPortugal’s most striking buildings were usually built near waterways and on floodplains due to easier access to water supply. This proximity, besides causing an increased probability of pathologies due to rising damp also brings a higher exposure to the risk of flooding. After the occurrence of a flood, all building elements below the flood water level will remain with high water contents, with all the negative consequences that this fact can cause, namely, the degradation of the materials. Therefore, it is very important to promote the fast drying of these building elements to prevent worse consequences, either structural, safety, or heritage conservation. In a recent investigation undertaken under a collaboration project involving the University of Coimbra and University of Porto, an innovative treatment system to combat rising damp in historical buildings was developed: the wall-base ventilation system. Currently, investigations have focused on analyzing the technical feasibility of adapting this system for drying out walls of historical buildings after floods.

Dynamic Response of Tall Buildings on Sedimentary Basin to Long-Period Seismic Ground Motion

Characteristics of long-period seismic ground motion and response of tall buildings are investigated in this paper to promote earthquake proof countermeasures considering the damage caused by the 2011 Tohoku earthquake. 3D finite difference method and the reciprocal theorem are used to examine the effect of sedimentary basin structures on seismic wave amplification. Natural period and damping of tall buildings are evaluated by ambient vibration tests and earthquake response observation during construction or demolition of the buildings. The effects of dynamic soil-structure interaction on response amplification of tall buildings are confirmed applying wave propagation theory to a continuum building model. Finally, a newly built base-isolated building with an isolated rooftop laboratory is introduced for full-scale long-period shaking experiment by installing actuators and jacks. Experience of long-period shaking in the building is also available with virtual reality view of indoor damage, which is effective for promotion of seismic countermeasures such as fixing furniture and safe evacuation.

Envelope Random Decrement Technique for Identification of Nonlinear Damping of Tall Buildings

AbstractTo accurately identify the nonlinear damping ratio of tall buildings, the authors propose an envelope random decrement technique (RDT). To verify the accuracy of the envelope RDT for the evaluation of amplitude-dependent nonlinear damping ratio, an iterative computing method, which can accurately work out the response of structures whose parameters depend on the response amplitude in any form, is also proposed. Then, using three different damping models in the numerical simulations, of which the response is calculated by the proposed iterative computing method, the applicabilities of traditional RDT, RDT ranked by peak amplitude, and the envelope RDT presented in this paper for the evaluation of amplitude-dependent nonlinear damping ratio are analyzed and compared. Results indicate that envelope RDT is better than the other two methods for the evaluation of amplitude-dependent nonlinear damping ratio. Finally, the envelope RDT is applied to identify the damping ratios of the Shanghai World Financi...

Integrating Double-Skin Façades and Mass Dampers for Structural Safety and Energy Efficiency

AbstractA new integrated control system was recently proposed to combine double-skin facades and mass dampers in buildings to improve both building safety and energy efficiency. Double-skin facade systems protect and insulate buildings with two heavy glass layers between which air is allowed to flow for ventilation. By enabling movements in the outer facade skin, the authors proposed to (1) use them as mass dampers to reduce structural vibration and damage during earthquakes and wind storms and (2) adjust the gap size between the outer and inner skins to control the ventilation rate and improve energy efficiency. The synergy of the proposed system can lead to buildings that are structurally safe, energy efficient, and ultimately sustainable. In this paper, two structural control strategies—passive and active—are considered. The facade damper system was formulated first, and stochastic and historical earthquake responses were simulated. Then, the damper parameters (stiffness and damping coefficients) for p...

Lung inflammation caused by inhaled toxicants: a review.

Exposure of the lungs to airborne toxicants from different sources in the environment may lead to acute and chronic pulmonary or even systemic inflammation. Cigarette smoke is the leading cause of chronic obstructive pulmonary disease, although wood smoke in urban areas of underdeveloped countries is now recognized as a leading cause of respiratory disease. Mycotoxins from fungal spores pose an occupational risk for respiratory illness and also present a health hazard to those living in damp buildings. Microscopic airborne particulates of asbestos and silica (from building materials) and those of heavy metals (from paint) are additional sources of indoor air pollution that contributes to respiratory illness and is known to cause respiratory illness in experimental animals. Ricin in aerosolized form is a potential bioweapon that is extremely toxic yet relatively easy to produce. Although the aforementioned agents belong to different classes of toxic chemicals, their pathogenicity is similar. They induce the recruitment and activation of macrophages, activation of mitogen-activated protein kinases, inhibition of protein synthesis, and production of interleukin-1 beta. Targeting either macrophages (using nanoparticles) or the production of interleukin-1 beta (using inhibitors against protein kinases, NOD-like receptor protein-3, or P2X7) may potentially be employed to treat these types of lung inflammation without affecting the natural immune response to bacterial infections.

New electrical tomographic method to determine dampness in historical buildings

Abstract This paper presents a new, nondestructive method of testing brick wall dampness in wall structures. The setup was used to determine the moisture in a specially built laboratory model. Topological methods and the gradient technique are used to optimize the approach. A forward model of a wall was constructed to solve the inverse problem resulting in moisture buildup inside the wall.

Treatment of rising damp in historic buildings: Experimental campaign of wall base ventilation and interface effect analysis

Abstract The treatment of rising damp in historical building walls is a very complex procedure. In this work it is presented an extension of the continuous “in situ” results of the rising damp treatment conducted in a Portuguese historical church, using the wall base ventilation technology. The results, registered over four years, clearly reveal the best ventilations periods and indicate that the best solutions must correspond to admit outside air during summer periods and inside air during winter periods. Furthermore, another important aspect was to better understand the difference in absorption behaviour between walls with and without joints when the rising damp treatment is conducted. It also presented an experimental campaign and a critical analysis of water absorption in samples of clay brick with and without joints and joints with different contact configurations (perfect contact, hydraulic continuity and air space between layers). The results showed that when the moisture reaches the interface, the wetting process gets slower due to the interfaces hygric resistance. This resistance was more pronounced for joints with air space between layers and less for joints with hydraulic continuity.

Effects of turbulence intensity and exterior geometry on across-wind aerodynamic damping of rectangular super-tall buildings

Across-wind aerodynamic damping ratios are identified from the wind-induced acceleration responses of 15 aeroelastic models of rectangular super-high-rise buildings in various simulated wind conditions by using the random decrement technique. The influences of amplitude-dependent structural damping ratio and natural frequency on the estimation of the aerodynamic damping ratio are discussed and the identifying method for aerodynamic damping is improved at first. Based on these works, effects of turbulence intensity Iu, aspect ratio H/B, and side ratio B/D on the across-wind aerodynamic damping ratio are investigated. The results indicate that turbulence intensity and side ratio are the most important factors that affect across-wind aerodynamic damping ratio, whereas aspect ratio indirectly affects the aerodynamic damping ratio by changing the response amplitude. Furthermore, empirical aerodynamic damping functions are proposed to estimate aerodynamic damping ratios at low and high reduced speeds for rectangular super-high-rise buildings with an aspect ratio in the range of 5 to 10, a side ratio of 1/3 to 3, and turbulence intensity varying from 1.7% to 25%.

Deformation Capacity of Steel Shear Panel Damper and its Reflection to AIJ Design Requirements

Shear panel dampers consisting of stiffeners and panels surrounded by four flanges are used as aseismic hysteretic dampers for buildings in Japan. Cracks can form easily in a shear panel damper when shear buckling occurs during the cyclic loading caused by a severe earthquake.For a relatively thin panel with a large width-to-thickness ratio, the damper’s plastic deformation capacity and the presence of shear buckling can be evaluated from the maximum deformation angle. However, when it is relatively small, very-low-cycle fatigue life for a relatively thick panel must be known to predict the usage limit of the damper, because the failure pattern changes when cracks form in the weld between the panels and flanges. Fatigue life relations for a thick shear panel damper with parameters of normalized width-to-thickness ratio and deformation angle are presented. A method for predicting the fatigue life under severe earthquake conditions is also presented. To validate the prediction expression, cyclic loading tests were performed on a shear panel damper and reviewed. The applicability of the method for predicting the fatigue life was confirmed through non-stationary cyclic loading tests. These results showed the validity and effectiveness of the expressions and the method.

A general extended Kalman filter for simultaneous estimation of system and unknown inputs

The traditional Extended Kalman filter (EKF) is a useful tool for structural parameter identification with limited observations. It is, however, not applicable when the excitations on the structure are unknown or the excitation locations are not monitored. A novel Extended Kalman filter approach referred to as the General Extended Kalman filter with unknown inputs (GEKF-UI) is proposed to estimate the structural parameters and the unknown excitations (inputs) simultaneously. The proposed GEKF-UI gives an analytical EKF solution dealing with the more general measurement scenarios with the existing EKF methods as its special cases. Existing constraints on sensor configuration have been removed enabling more general application to complex structures. Simulation results from a 3-storey linear damped shear building, an ASCE benchmark structure and a two-storey planar frame structure are used to validate the proposed method for both time-invariant and time-varying system identification.

Protein profiles of nasal lavage fluid from individuals with work-related upper airway symptoms associated with moldy and damp buildings.

Upper airway irritation is common among individuals working in moldy and damp buildings. The aim of this study was to investigate effects on the protein composition of the nasal lining fluid. The prevalence of symptoms in relation to work environment was examined in 37 individuals working in two damp buildings. Microbial growth was confirmed in one of the buildings. Nasal lavage fluid was collected from 29 of the exposed subjects and 13 controls, not working in a damp building. Protein profiles were investigated with a proteomic approach and evaluated by multivariate statistical models. Subjects from both workplaces reported upper airway and ocular symptoms. Based on protein profiles, symptomatic subjects in the two workplaces were discriminated from each other and separated from healthy controls. The groups differed in proteins involved in inflammation and host defense. Measurements of innate immunity proteins showed a significant increase in protein S100-A8 and decrease in SPLUNC1 in subjects from one workplace, while alpha-1-antitrypsin was elevated in subjects from the other workplace, compared with healthy controls. The results show that protein profiles in nasal lavage fluid can be used to monitor airway mucosal effects in personnel working in damp buildings and indicate that the profile may be separated when the dampness is associated with the presence of molds.

Design of the Ventilated Air Channel to Resolve Moisture Problems in the Historical Church

The purpose of the research is to find adequate solution against rising damp in historical buildings. The improvement of this case is with ventilated air channel. Special part of historical buildings are churches because not use routinely as for example museums, galleries. We are designed 10 differently construction of ventilated air channel. These are: open or closed, with overpressure and underpressure. We use for verification relevance these construction we simulated in software Ansys CFX the air flow of channels. We modeling the equal segment of the channels. This research should be offer for architects the solution against problems of rising damp for historical buildings. For find the right solution is necessary to research everyone case. The aim of the research is to prepare the design process of the ventilated air channels for the architects without simulation every building, cross section or geometry of these construction.

Remediating buildings damaged by dampness and mould for preventing or reducing respiratory tract symptoms, infections and asthma.

Dampness and mould in buildings have been associated with adverse respiratory symptoms, asthma and respiratory infections of inhabitants. Moisture damage is a very common problem in private houses, workplaces and public buildings such as schools. To determine the effectiveness of repairing buildings damaged by dampness and mould in order to reduce or prevent respiratory tract symptoms, infections and symptoms of asthma. We searched CENTRAL (2014, Issue 10), MEDLINE (1951 to November week 1, 2014), EMBASE (1974 to November 2014), CINAHL (1982 to November 2014), Science Citation Index (1973 to November 2014), Biosis Previews (1989 to June 2011), NIOSHTIC (1930 to March 2014) and CISDOC (1974 to March 2014). Randomised controlled trials (RCTs), cluster-RCTs (cRCTs), interrupted time series studies and controlled before-after (CBA) studies of the effects of remediating dampness and mould in a building on respiratory symptoms, infections and asthma. Two authors independently extracted data and assessed the risk of bias in the included studies. We included 12 studies (8028 participants): two RCTs (294 participants), one cRCT (4407 participants) and nine CBA studies (3327 participants). The interventions varied from thorough renovation to cleaning only.Repairing houses decreased asthma-related symptoms in adults (among others, wheezing (odds ratio (OR) 0.64; 95% confidence interval (CI) 0.55 to 0.75) and respiratory infections (among others, rhinitis (OR 0.57; 95% CI 0.49 to 0.66), two studies, moderate-quality evidence). For children, we did not find a difference between repaired houses and receiving information only, in the number of asthma days or emergency department visits because of asthma (one study, moderate-quality evidence).One CBA study showed very low-quality evidence that after repairing a mould-damaged office building, asthma-related and other respiratory symptoms decreased. In another CBA study, there was no difference in symptoms between full or partial repair of houses.For children in schools, the evidence of an effect of mould remediation on respiratory symptoms was inconsistent and out of many symptom measures only respiratory infections might have decreased after the intervention. For staff in schools, there was very low-quality evidence that asthma-related and other respiratory symptoms in mould-damaged schools were similar to those of staff in non-damaged schools, both before and after intervention. We found moderate to very low-quality evidence that repairing mould-damaged houses and offices decreases asthma-related symptoms and respiratory infections compared to no intervention in adults. There is very low-quality evidence that although repairing schools did not significantly change respiratory symptoms in staff, pupils' visits to physicians due to a common cold were less frequent after remediation of the school. Better research, preferably with a cRCT design and with more validated outcome measures, is needed.

First Mode Damping Ratios for Buildings

Expressions for the expected value of the first mode damping ratio are derived by using 122 seismic responses from concrete buildings and 81 from steel. The results include dissipation at the soil-structure interface and are appropriate for situations in which this source of dissipation is not included in the model. Comparisons between models of different complexity indicate the appropriateness of using a single regressor, for which the building height is used. It is shown that the Fisher information about damping increases with the number of response cycles; this result is used to define weights for the residuals of the regression. The effective damping in steel buildings, with the exception of very tall structures, is found to be larger than the 2% typically used in practice, whereas the 5% assigned to concrete proves to be similar to the mean of the data set.