Search results for: seismic resistance

Authors: Katherine Del Carmen Camacho Zorogastua, Victor Hugo Gallo Ramos, Jhon Walter Gomez Lora

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Marine hydrocarbon exploration (oil and natural gas) activities are developed using 2D, 3D and 4D seismic prospecting techniques where sound waves are directed from a seismic vessel emitted every few seconds depending on the variety of air compressors, which cross the layers of rock at the bottom of the sea and are reflected to the surface of the water. Hydrophones receive and record the reflected energy signals for cross-sectional mapping of the lithological profile in order to identify possible areas where hydrocarbon deposits can be formed. However, they produce several significant negative environmental impacts on the marine ecosystem and in the social and economic sectors. Therefore, the objective of the research is to publicize the negative impacts and environmental measures that must be carried out during the development of these activities to prevent and mitigate water quality, the population involved (fishermen) and the marine biota (e.g., Cetaceans, fish) that are the most vulnerable. The research contains technical environmental aspects based on bibliographic sources of environmental studies approved by the Peruvian authority, research articles, undergraduate and postgraduate theses, books, guides, and manuals from Spain, Australia, Canada, Brazil, and Mexico. It describes the negative impacts on the environment and population (fishing sector), environmental prevention, mitigation, recovery and compensation measures that must be properly implemented and the cases of global sea species stranding, for which international experiences from Spain, Madagascar, Mexico, Ecuador, Uruguay, and Peru were referenced. Negative impacts on marine fauna, seawater quality, and the socioeconomic sector (fishermen) were identified. Omission or inadequate biological monitoring in mammals could alter their ability to communicate, feed, and displacement resulting in their stranding and death. In fish, they cause deadly damage to physical-physiological type and in their behavior. Inadequate wastewater treatment and waste management could increase the organic load and oily waste on seawater quality in violation of marine flora and fauna. The possible estrangement of marine resources (fish) affects the economic sector as they carry out their fishing activity for consumption or sale. Finally, it is concluded from the experiences gathered from Spain, Madagascar, Mexico, Ecuador, Uruguay, and Peru that there is a cause and effect relationship between the inadequate development of seismic exploration activities (cause) and marine species strandings (effect) since over the years, stranded or dead marine mammals have been detected on the shores of the sea in areas of seismic acquisition of hydrocarbons. In this regard, it is recommended to establish technical procedures, guidelines, and protocols for the monitoring of marine species in order to contribute to the conservation of hydrobiological resources.

Keywords: 3D seismic prospecting, cetaceans, significant environmental impacts, prevention, mitigation, recovery, environmental compensation

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Authors: Seyyed Payman Ziapour, Ahmadali Enayati, Sadegh Kheiri, Farzaneh Sahraei-Rostami, Reza Ali Mohammadpour, Mahmoud Fazeli-Dinan, Mohsen Aarabi, Fatemeh Asgarian, Seyed Hassan Nikookar, Mohammad Sarafrazi

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Rhipicephalus bursa (R. bursa) is a two-host ixodid tick with wide distribution in north of Iran especially in domestic animals of Mazandaran Province. The prolonged or incorrect use of chemical insecticides has led to build up of resistance in hard ticks in many areas of the world. Lack of basic information on resistance status of R. bursa was the reason behind this study to determine the susceptibility status of the species to lambda-cyhalothrin insecticide in Mazandaran Province. From May 2013 to March 2014, R. bursa ticks were collected on sheep, goat and cattle in different districts of Mazandaran Province. The engorged female ticks were reared in a controlled insectary for producing 12-18 days old larvae for larval packet test (LPT) bioassay against discriminant doses of lambda-cyhalothrin 5% EC (MAC SILAT®). 80% of ten pooled tick populations were susceptible to lambda-cyhalothrin as resistance ratios (RR50s) varied from 1 to 2.94 when compared with the most susceptible population NH-16. Only GK-12 and BF-6 populations (from plain areas of Galugah and Fereydunkenar Counties, respectively) were classified as resistant level I at LC50 level. Population NK-2 (from woodland areas of Kojour district in Nowshahr County) showed the highest resistance ratio of RR99 = 4.32 and 30% of tick populations were resistant at LC99 level. Our research showed initiation of lambda-cyhalothrin resistance in Rhipicephalus bursa populations in Mazandaran Province, Northern Iran. This is considered a warning to policy makers for disease control in the study area. This research is a part of the PhD thesis of SP. Ziapour by grant No. 92-89 in Student Research Committee, Mazandaran University of Medical Sciences, Iran.

Keywords: Rhipicephalus bursa, hard tick, lambda-cyhalothrin resistance, Iran

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Authors: Juan Carlos Baena, Zhongxiao Peng

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Ultra-high molecular weight polyethylene (UHMWPE) is extensively used in industrial and biomedical fields. The slippery nature of UHMWPE makes this material suitable for surface bearing applications, however, the operational conditions limit the lubrication efficiency, inducing boundary and mixed lubrication in the tribological system. The lack of lubrication in a tribological system intensifies friction, contact stress and consequently, operating temperature. With temperature increase, the material’s mechanical properties are affected, and the lifespan of the component is reduced. The understanding of how mechanical properties and wear performance of UHMWPE change when the temperature is increased has not been clearly identified. The understanding of the wear and mechanical performance of UHMWPE at different temperature is important to predict and further improve the lifespan of these components. This study evaluates the effects of temperature variation in a range of 20 °C to 60 °C on the hardness and the wear resistance of UHMWPE. A reduction of the hardness and wear resistance was observed with the increase in temperature. The variation of the wear rate increased 94.8% when the temperature changed from 20 °C to 50 °C. Although hardness is regarded to be an indicator of the material wear resistance, this study found that wear resistance decreased more rapidly than hardness with the temperature increase, evidencing a low material stability of this component in a short temperature interval. The reduction of the hardness was reflected by the plastic deformation and abrasion intensity, resulting in a significant wear rate increase.

Keywords: hardness, surface bearing, tribological system, UHMWPE, wear

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Authors: Sara Boulmai̇z

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In order to study the microbiological quality of chawarma sold in Biskra, a sampling through some fastfoods of the city was done, the parameters studied are highlighted according to the criteria required by the country's trade management. Microbiological analyzes revealed different levels of contamination by microorganisms. The 10 samples were of an overall view of unsatisfactory quality, and according to the standards, no sample was satisfactory. The range of total aerobic mesophilic flora found is between 105 and 1.2 × 10 7 CFU / g, that of fecal coliforms is 104 to 2.4 × 10 5 CFU / g. The suspected pathogenic staphylococci were between 3.103 and 2.7.106 CFU / g. Salmonellae were absent in all samples, whereas sulphite-reducing anaerobes were present in a single sample. The rate of E. cloacae was between 103 and 6.104 CFU / g. As for fungi and safe mice, their rate was 103 to 107 CFU / g. The study of the sensitivity of antibiotics showed multi-resistance to all the antibiotics tested, although there is a sensitivity towards others. All strains of Staphylococcus aureus tested demonstrated resistance against erythromycin, 30% against streptomycin, and 10% against tetracycline. While the strains of E. cloacae were resistant in all strains to amoxicillin, ceftazidime, cefotaxime, and erythromycin, while they were sensitive to fosfomycin, sulfamethoxazole trimethoperine, ciprofloxacin, and tetracycline. While against chlorophenicol and ofloxacin, the sensitivity was dominant, although there was intermediate resistance. In this study demonstrates that foodborne illnesses remain a problem that arises in addition to the increasingly observed bacterial resistance and that, after all, healthy eating is a right.

Keywords: chawarma, microbiological quality, pathogens., street food

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Authors: S. A. Hashemi, A. Khoshraftar

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This paper presents the influence of the vertical seismic component on the non-linear dynamics analysis of three different structures. The subject structures were analyzed and designed according to recent codes. This paper considers three types of buildings: 5-, 10-, and 15-story buildings. The non-linear dynamics analysis of the structures with assuming elastic-perfectly-plastic behavior was performed using Ram Perform-3D software; the horizontal component was taken into consideration with and without the incorporation of the corresponding vertical component. Dynamic responses obtained for the horizontal component acting alone were compared with those obtained from the simultaneous application of both seismic components. The results show that the effect of the vertical component of the ground motion may increase the axial load significantly in the interior columns and consequently, the stories. The plastic mechanisms would be changed. The P-Delta effect is expected to increase. The punching base plate shear of the columns should be considered. Moreover, the vertical component increases the input energy when the structures exhibit inelastic behavior and are taller.

Keywords: inelastic behavior, non-linear dynamic analysis, steel structure, vertical component

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Authors: A. Kahil, A. Nekmouche, N. Khelil, I. Hamadou, M. Hamizi, Ne. Hannachi

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The objective of this work is to study the influence of the nonlinear behavior models of the concrete (concrete_BAEL and concrete_UNI) as well as the confinement brought by the transverse reinforcement on the seismic response of reinforced concrete frame (RC/frame). These models as well as the confinement are integrated in the Cast3m finite element calculation code. The consideration of confinement (TAC, taking into account the confinement) provided by the transverse reinforcement and the non-consideration of confinement (without consideration of containment, WCC) in the presence and absence of a vertical load is studied. The application was made on a reinforced concrete frame (RC/frame) with 3 levels and 2 spans. The results show that on the one hand, the concrete_BAEL model slightly underestimates the resistance of the RC/frame in the plastic field, whereas the concrete_uni model presents the best results compared to the simplified model "concrete_BAEL", on the other hand, for the concrete-uni model, taking into account the confinement has no influence on the behavior of the RC/frame under imposed displacement up to a vertical load of 500 KN.

Keywords: reinforced concrete, nonlinear calculation, behavior laws, fiber model confinement, numerical simulation

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Authors: Mohamed Elassaly

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The damage status of RC buildings is greatly influenced by the characteristics of the imposed ground motion. Peak Ground Acceleration and frequency contents are considered the main two factors that affect ground motion characteristics; hence, affecting the seismic response of RC structures and consequently their damage state. A detailed investigation on the combined effects of these two factors on damage assessment of RC buildings, is carried out. Twenty one earthquake records are analyzed and arranged into three groups, according to their frequency contents. These records are used in an investigation to define the expected damage state that would be attained by RC buildings, if subjected to varying ground motion characteristics. The damage assessment is conducted through examining drift ratios and damage indices of the overall structure and the significant structural components of RC building. Base and story shear of RC building model, are also investigated, for cases when the model is subjected to the chosen twenty one earthquake records. Nonlinear dynamic analyses are performed on a 2-dimensional model of a 12-story R.C. building.

Keywords: damage, frequency content, ground motion, PGA, RC building, seismic

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Authors: Tarek M. Alguhane, Ayman H. Khalil, Nour M. Fayed, Ayman M. Ismail

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An existing RC building in Madinah is seismically evaluated with and without infill wall. Four model systems have been considered i. e. model I (no infill), model IIA (strut infill-update from field test), model IIB (strut infill- ASCE/SEI 41) and model IIC (strut infill-Soft storey-ASCE/SEI 41). Three dimensional pushover analyses have been carried out using SAP 2000 software incorporating inelastic material behavior for concrete, steel and infill walls. Infill wall has been modeled as equivalent strut according to suggested equation matching field test measurements and to the ASCE/SEI 41 equation. The effect of building modeling on the performance point as well as capacity and demand spectra due to EQ design spectrum function in Madinah area has been investigated. The response modification factor (R) for the 5 story RC building is evaluated from capacity and demand spectra (ATC-40) for the studied models. The results are summarized and discussed.

Keywords: infill wall, pushover analysis, response modification factor, seismic assessment

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Authors: Solomon Gebremariam, Mulugeta Naizigi, Aregawi Haileselassie

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Background: Knowledge of the pattern of bacterial isolates and their antimicrobial susceptibility is crucial for guiding empirical treatment and infection prevention and control measures. Objective: The aim of this study was to analyze the pattern of bacterial isolates and their susceptibility patterns from various specimens. Methods: Retrospectively, a total of 1067 microbiological culture results that were isolated, characterized, and identified by standard microbiological methods and whose antibiotic susceptibility was determined using CLSI guidelines between 2017 and 2019 were retrieved and analyzed. Data were entered and analyzed using the Stata release 10.1 statistical package. Result: The positivity rate of culture was 26.04% (419/1609). The most common bacteria isolated were S. aureus 23.8% (94), E. coli 15.1% (60), Klebsiella pneumonia 14.1% (56), Pseudomonas aeruginosa 8.5% (34), and CONS 7.3% (29). S. aureus and CONS showed a high (58.1% - 96.2%) rate of resistance to most antibiotics tested. They were less resistant to Vancomycin which is 18.6% (13/70) and 11.8% (2/17), respectively. Similarly, the resistance of E. coli, Klebsella pneumonia, and Pseudomonas aeruginosa was high (69.4% - 100%) to most antibiotics. They were less resistant to Ciprofloxacilin, which is 41.1% (23/56), 19.2% (10/52), and 16.1% (5/31), respectively. Conclusion: This study has shown that there is a high rate of antibiotic resistance among bacterial isolates in this hospital. A combination of Vancomycin and Ciprofloxacin should be considered in the choice of antibiotics for empirical treatment of suspected infections due to S. aureus, CONS, E. coli, Klebsiella pneumonia, Pseudomonas such as in infections within hospital setup.

Keywords: antimicrobial, resistance, bacteria, hospital

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Authors: Zhanat Umarova

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Until the present time, modeling of the pores form influence on the hydraulic resistance of membranes and their permeability has not been analyzed. The aim of the given work is the theoretical consideration of the issue on the productivity of polymer membranes with the profile pores and determination of the optimum form of pores.

Keywords: modeling, polymer membranes, permeability, pore’s density

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Authors: M. Ottenbrite, G. Yilmaz, J. Devenish, M. Kang, H. Dan, M. Lin, C. Lau, C. Carrillo, K. Bessonov, J. Nash, E. Topp, J. Guan

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Consumption of food contaminated by antibiotic-resistant (AR) bacteria may lead to the transmission of AR genes in the gut microbiota and cause AR bacterial infection, a significant public health concern. However, information is limited on if and how background microbes from the food matrix (food microbes) may influence resistance transmission. Thus, we assessed the colonization of a β-lactam resistant Salmonella Heidelberg strain (donor) and a β-lactam susceptible S. Typhimurium strain (recipient) and the transfer of the resistance genes in the mouse gut in the presence or absence of food microbes that were derived from washing freshly-harvested carrots. Mice were pre-treated with streptomycin and then inoculated with both donor and recipient bacteria or recipient only. Fecal shedding of the donor, recipient, and transconjugant bacteria was enumerated using selective culture techniques. Transfer of AR genes was confirmed by whole genome sequencing. Gut microbial composition was determined by 16s rRNA amplicon sequencing. Significantly lower numbers of donors and recipients were shed from mice that were inoculated with food microbes compared to those without food microbe inoculation. S. Typhimurium transconjugants were only recovered from mice without inoculation of food microbes. A significantly higher survival rate was in mice with vs. without inoculation of food microbes. The results suggest that the food microbes may compete with both the donor and recipient Salmonella, limit their growth and reduce transmission of the β-lactam resistance gene in the mouse gut.

Keywords: antibiotic resistance, gene transfer, gut microbiota, Salmonella infection

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Authors: H. Kishor, G. Prabhuling, D. S. Ambika, D. P. Prakash

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The chemical mutagens have become important tool to enhance agronomic traits of banana crop. It is being used to develop fusarium resistance lines in various susceptible banana cultivars. There are several mutagens like EMS and NaN3 available for banana crop improvement and each mutagen has its own important role as positive or negative effects on growth and development of banana plants. Explants from shoot tip culture were treated with various EMS (0.30, 0.60, 0.90 and 0.12%) and NaN3 (0.01, 0.02 and 0.03%) concentrations. The putative mutants obtained after in vitro rooting were subjected for artificial inoculation of Fusarium oxysporum f.sp. cubense. Screening putative mutants resistance to Panama disease was carried out by using syringe method of inoculation. It was observed that, EMS treated mutants were more susceptible compared to NaN3 treatment. Among the NaN3 doses 0.01% found to produce 3 resistant lines during preliminary screening under greenhouse conditions.

Keywords: Nanjangud rasabale, EMS, NaN3, putative mutants

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Authors: Ali Kassem

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Background: In the last few years, factors such as insulin resistance (IR) and hepatic steatosis have been linked to progression of hepatic fibrosis.Patients with chronic liver disease, and cirrhosis in particular, are known to be prone to IR. However, chronic HCV (hepatitis C) infection may induce IR, regardless of the presence of liver cirrhosis. Our aims are to study insulin resistance (IR) assessed by HOMA-IR (Homeostatic Model Assessment Insulin Resistance) as a possible risk factor in disease progression in cirrhotic patients and to evaluate the role of IR in hepatic fibrosis progression. The correlations of HOMA-IR values to laboratory, virological and histopathological parameters of chronic HCV are also examined. Methods: The study included 50 people divided into 30 adult chronic hepatitis C patients diagnosed by PCR (polymerase chain reaction) within previous 6 months and 20 healthy controls. The functional and morphological status of the liver were evaluated by ultrasonography and laboratory investigations including liver function tests and by liver biopsy. Fasting blood glucose and fasting insulin levels were measured and body mass index and insulin resistance were calculated. Patients having HOMA-IR >2.5 were labeled as insulin resistant. Results: Chronic hepatitis C patients with IR showed significantly higher mean values of BMI (body mass index) and fasting insulin than those without IR (P < 0.000). Patients with IR were more likely to have steatosis (p = 0.006), higher necroinflammatory activity (p = 0.05). No significant differences were found between the two groups regarding hepatic fibrosis. Conclusion: HOMA-IR measurement could represent a novel marker to identify the cirrhotic patients at greater risk for the progression of liver disease. As IR is a potentially modifiable risk factor, these findings may have important prognostic and therapeutic implications. Assessment of IR by HOMA-IR and improving insulin sensitivity are recommended in patients with HCV and related chronic liver disease.

Keywords: hepatic fibrosis, hepatitis C virus infection, hepatic steatosis, insulin resistance

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Authors: Rohan V. Ambekar, Shrirang N. Tande

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The present study estimates the seismic response reduction factor (R) of reinforced concrete special moment resisting frame (SMRF) with and without shear wall using static nonlinear (pushover) analysis. Calculation of response reduction factor (R) is done as per the new formulation of response reduction factor (R) given by Applied Technology Council (ATC)-19 which is the product of strength factor (Rs), ductility factor (Rµ) and redundancy factor (RR). The analysis revealed that these three factors affect the actual value of response reduction factor (R) and therefore they must be taken into consideration while determining the appropriate response reduction factor to be used during the seismic design process. The actual values required for determination of response reduction factor (R) is worked out on the basis of pushover curve which is a plot of base shear verses roof displacement. Finally, the calculated values of response reduction factor (R) of reinforced concrete special moment resisting frame (SMRF) with and without shear wall are compared with the codal values.

Keywords: response reduction factor, ductility ratio, base shear, special moment resisting frames

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Authors: Nandy Putra, Atrialdipa Duanovsah, Kristofer Haliansyah

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The aim of this research is to design a LHP with low thermal resistance and low condenser temperature. A Self-designed cascade LHP was tested by using biomaterial, sintered copper powder, and aluminum screen mesh as the wick. Using pure water as the working fluid for the first level of the LHP and 96% alcohol as the working fluid for the second level of LHP, the experiments were run with 10W, 20W, and 30W heat input. Experimental result shows that the usage of biomaterial as wick could reduce more temperature at evaporator than by using sintered copper powder and screen mesh up to 22.63% and 37.41% respectively. The lowest thermal resistance occurred during the usage of biomaterial as wick of heat pipe, which is 2.06 ^oC/W. The usage of cascade system could be applied to LHP to reduce the temperature at condenser and reduced thermal resistance up to 17.6%.

Keywords: biomaterial, cascade loop heat pipe, screen mesh, sintered Cu

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Authors: Ankit Tyagi, Reet Kamal Tiwari, Naveen James

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In India, landslides are the most frequently occurring disaster in the regions of the Himalayas and the Western Ghats. The steep slopes and land use in these areas are quite apprehensive. In the recent past, many landslide hazard zonation (LHZ) works have been carried out in the Himalayas. However, the preparation of LHZ maps considering temporal factors such as seismic ground shaking, seismic amplification at surface level, and rainfall are limited. Hence this study presents a comprehensive use of the multi-criteria decision-making (MCDM) method in landslide risk assessment. In this research, we conducted both geospatial and geotechnical analysis to minimize the danger of landslides. Geospatial analysis is performed using high-resolution satellite data to produce landslide causative factors which were given weightage using the MCDM method. The geotechnical analysis includes a slope stability check, which was done to determine the potential landslide slope. The landslide risk map can provide useful information which helps people to understand the risk of living in an area.

Keywords: landslide hazard zonation, PHA, AHP, GIS

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Authors: Daniel Y. Abebe, Jaehyouk Choi

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There are several types of metal-based devices conceived as dampers for the seismic energy absorber whereby damages to the major structural components could be minimized for both new and existing structures. This paper aimed to develop and evaluate structural performance of slit circular shear panel damper for passive seismic energy protection by inelastic deformation. Structural evaluation was done using commercially available nonlinear FE simulation program. The main parameters considered are: diameter-to-thickness (D/t) ratio and slit length-to-width ratio (l/w). Depending on these parameters three different buckling modes and hysteretic behaviors were found: yielding prior to buckling without strength degradation, yielding prior to buckling with strength degradation, and yielding with buckling and strength degradation which forms pinching at initial displacement. The susceptible location at which the possible crack is initiated is also identified for selected specimens using rupture index.

Keywords: slit circular shear panel damper, hysteresis characteristics, slip length-to-width ratio, D/t ratio, FE analysis

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Authors: Allamula Ashok, Peela Lasya, Daljin Jacob, P. Muhammed Razi, Satyesh Kumar Yadav

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We report zinc (Zn) as a seed layer material and a need for a specific disposition sequence to grow ultrathin silver (Ag) films on quartz (SiO₂). Ag films of thickness 4, 6, 8 and 10 nm were deposited by DC magnetron sputtering without and with Zn seed layer thickness of 1, 2 and 4 nm. The effect of Zn seed layer thickness and its annealing on the surface morphology, sheet resistance, and stability of ultrathin Ag films is investigated. We show that by increasing Zn seed layer thickness from 1 to 2 nm, there is a 5-order reduction in sheet resistance of 6 nm Ag films. We find that annealing of the seed layer is crucial to achieving stability of ultrathin Ag films. 6 nm Ag film with 2 nm Zn is unstable to 100 oC annealing, while the 6 nm Ag film with annealed 2 nm Zn seed layer is stable. 2 nm Zn seeded 8 nm Ag film maintained a constant sheet resistance of 7 Ω/□ for all 6 months of exposure to ambient conditions. Among the ultrathin film grown, 8nm Ag film with 2nm Zn seed layer had the best figure of merit with sheet resistance of 7 Ω/□, mean absolute surface roughness (Ra) ~1 nm, and optical transparency of 61 %. Such stable exposed ultrathin Ag films can find applications as catalysts, sensors, and transparent and conductive electrodes for solar cells, LEDs and plasmonic devices.

Keywords: ultrathin Ag films, magnetron sputtering, thermal stability, seed layer, exposed silver, zinc.

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Authors: S. Dorbani, M. Badaoui, D. Benouar

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The aim of this paper is to investigate the effect of the building fundamental period of reinforced concrete buildings of (6, 9, and 12-storey), with different floor plans: Symmetric, mono-symmetric, and unsymmetric. These structures are erected at different epicentral distances. Using the Boumerdes, Algeria (2003) earthquake data, we focused primarily on the establishment of the deterministic formulation linking the base shear force to two parameters: The first one is the fundamental period that represents the numerical fingerprint of the structure, and the second one is the epicentral distance used to represent the impact of the earthquake on this force. In a second step, with a view to highlight the effect of uncertainty in these parameters on the analyzed response, these parameters are modeled as random variables with a log-normal distribution. The variability of the coefficients of variation of the chosen uncertain parameters, on the statistics on the seismic base shear force, showed that the effect of uncertainty on fundamental period on this force statistics is low compared to the epicentral distance uncertainty influence.

Keywords: base shear force, fundamental period, epicentral distance, uncertainty, lognormal variables, statistics

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Authors: Nesreddine Djafar Henni, Akram Khelaifia, Salah Guettala, Rachid Chebili

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Reinforced concrete shear walls and vertical plate-like elements play a pivotal role in efficiently managing a building's response to seismic forces. This study investigates how the performance of reinforced concrete buildings equipped with shear walls featuring different shear wall-to-frame stiffness ratios aligns with the requirements stipulated in the Algerian seismic code RPA99v2003, particularly in high-seismicity regions. Seven distinct 3D finite element models are developed and evaluated through nonlinear static analysis. Engineering Demand Parameters (EDPs) such as lateral displacement, inter-story drift ratio, shear force, and bending moment along the building height are analyzed. The findings reveal two predominant categories of induced responses: force-based and displacement-based EDPs. Furthermore, as the shear wall-to-frame ratio increases, there is a concurrent increase in force-based EDPs and a decrease in displacement-based ones. Examining the distribution of shear walls from both force and displacement perspectives, model G with the highest stiffness ratio, concentrating stiffness at the building's center, intensifies induced forces. This configuration necessitates additional reinforcements, leading to a conservative design approach. Conversely, model C, with the lowest stiffness ratio, distributes stiffness towards the periphery, resulting in minimized induced shear forces and bending moments, representing an optimal scenario with maximal performance and minimal strength requirements.

Keywords: dual RC buildings, RC shear walls, modeling, static nonlinear pushover analysis, optimization, seismic performance

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Authors: Lakmini Wijesooriya, Vicki Chalker, Jessica Day, Priyantha Perera, N. P. Sunil-Chandra

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M. pneumoniae has been identified as an etiology for exacerbation of asthma (EQA), although viruses play a major role in EOA. M. pneumoniae infection is treated empirically with macrolides, and its antibiotic sensitivity is not detected routinely. Characterization of the organism by genotyping and determination of macrolide resistance is important epidemiologically as it guides the empiric antibiotic treatment. To date, there is no such characterization of M. pneumoniae performed in Sri Lanka. The present study describes the characterization of M. pneumoniae detected from a child with EOA following a screening of 100 children with EOA. Of the hundred children with EOA, M. pneumoniae was identified only in one child by Real-Time polymerase chain reaction (PCR) test for identifying the community-acquired respiratory distress syndrome (CARDS) toxin nucleotide sequences. The M. pneumoniae identified from this patient underwent detection of macrolide resistance via conventional PCR, amplifying and sequencing the region of the 23S rDNA gene that contains single nucleotide polymorphisms that confer resistance. Genotyping of the isolate was performed via nested Multilocus Sequence Typing (MLST) in which eight (8) housekeeping genes (ppa, pgm, gyrB, gmk, glyA, atpA, arcC, and adk) were amplified via nested PCR followed by gene sequencing and analysis. As per MLST analysis, the M. pneumoniae was identified as sequence type 14 (ST14), and no mutations that confer resistance were detected. Resistance to macrolides in M. pneumoniae is an increasing problem globally. Establishing surveillance systems is the key to informing local prescriptions. In the absence of local surveillance data, antibiotics are started empirically. If the relevant microbiological samples are not obtained before antibiotic therapy, as in most occasions in children, the course of antibiotic is completed without a microbiological diagnosis. This happens more frequently in therapy for M. pneumoniae which is treated with a macrolide in most patients. Hence, it is important to understand the macrolide sensitivity of M. pneumoniae in the setting. The M. pneumoniae detected in the present study was macrolide sensitive. Further studies are needed to examine a larger dataset in Sri Lanka to determine macrolide resistance levels to inform the use of macrolides in children with EOA. The MLST type varies in different geographical settings, and it also provides a clue to the existence of macrolide resistance. The present study enhances the database of the global distribution of different genotypes of M. pneumoniae as this is the first such characterization performed with the increased number of samples to determine macrolide resistance level in Sri Lanka. M. pneumoniae detected from a child with exacerbation of asthma in Sri Lanka was characterized as ST14 by MLST and no mutations that confer resistance were detected.

Keywords: mycoplasma pneumoniae, Sri Lanka, characterization, macrolide resistance

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Authors: Rene Jimenez, Sonia E. Ruiz, Miguel A. Orellana

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On 09/19/2017, a Mw = 7.1 intraslab earthquake occurred in Mexico causing the collapse of about 40 buildings. Many of these were 5- or 6-story buildings with soft first story; so, it is desirable to perform a structural fragility analysis of typical structures representative of those buildings and to propose a reliable structural solution. Here, a typical 5-story building constituted by regular R/C moment-resisting frames in the first story and confined masonry walls in the upper levels, similar to the collapsed structures on the 09/19/2017 Mexico earthquake, is analyzed. Three different structural solutions of the 5-story building are considered: S1) it is designed in accordance with the Mexico City Building Code-2004; S2) then, the column dimensions of the first story corresponding to S1 are reduced, and S3) viscous dampers are added at the first story of solution S2. A number of dynamic incremental analyses are performed for each structural solution, using a 3D structural model. The hysteretic behavior model of the masonry was calibrated with experiments performed at the Laboratory of Structures at UNAM. Ten seismic ground motions are used to excite the structures; they correspond to ground motions recorded in intermediate soil of Mexico City with a dominant period around 1s, where the structures are located. The fragility curves of the buildings are obtained for different values of the maximum inter-story drift demands. Results show that solutions S1 and S3 give place to similar probabilities of exceedance of a given value of inter-story drift for the same seismic intensity, and that solution S2 presents a higher probability of exceedance for the same seismic intensity and inter-story drift demand. Therefore, it is concluded that solution S3 (which corresponds to the building with soft first story and energy dissipation devices) can be a reliable solution from the structural point of view.

Keywords: demand hazard analysis, fragility curves, incremental dynamic analyzes, soft-first story, structural capacity

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Authors: Malleshappa Japagal, Srinivas Chitragar

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The use of waste plastic in pavement is becoming important alternative worldwide for disposal of plastic as well as to improve the stability of pavement and to meet out environmental issues. However, there are still concerns on fatigue and fracture resistance of Hot Mix Asphalt with the addition of plastic waste, (HMA-Plastic mixes) and moisture damage potential. The present study was undertaken to evaluate fracture resistance of HMA-Plastic mixes using semi-circular bending (SCB) test and moisture damage potential by Indirect Tensile strength (ITS) test using retained tensile strength (TSR). In this study, a dense graded asphalt mix with 19 mm nominal maximum aggregate size was designed in the laboratory using Marshall Mix design method. Aggregates were coated with different percentages of waste plastic (0%, 2%, 3% and 4%) by weight of aggregate and performance evaluation of fracture resistance and Moisture damage was carried out. The following parameters were estimated for the mixes: J-Integral or Jc, strain energy at failure, peak load at failure, and deformation at failure. It was found that the strain energy and peak load of all the mixes decrease with an increase in notch depth, indicating that increased percentage of plastic waste gave better fracture resistance. The moisture damage potential was evaluated by Tensile strength ratio (TSR). The experimental results shown increased TRS value up to 3% addition of waste plastic in HMA mix which gives better performance hence the use of waste plastic in road construction is favorable.

Keywords: hot mix asphalt, semi circular bending, marshall mix design, tensile strength ratio

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Authors: Gail Louw, Helena Boshoff, Taeksun Song, Clifton Barry

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Drug resistance in Mycobacterium tuberculosis is primarily attributed to mutations in target genes. These mutations incur a fitness cost and result in bacterial generations that are less fit, which subsequently acquire compensatory mutations to restore fitness. We hypothesize that mutations in specific drug target genes influence bacterial metabolism and cellular function, which affects its ability to develop subsequent resistance to additional agents. We aim to determine whether the sequential acquisition of drug resistance and specific mutations in a well-defined clinical M. tuberculosis strain promotes or limits the development of additional resistance. In vitro mutants resistant to pretomanid, linezolid, moxifloxacin, rifampicin and kanamycin were generated from a pan-susceptible clinical strain from the Beijing lineage. The resistant phenotypes to the anti-TB agents were confirmed by the broth microdilution assay and genetic mutations were identified by targeted gene sequencing. Growth of mono-resistant mutants was done in enriched medium for 14 days to assess in vitro fitness. Double resistant mutants were generated against anti-TB drug combinations at concentrations 5x and 10x the minimum inhibitory concentration. Subsequently, mutation frequencies for these anti-TB drugs in the different mono-resistant backgrounds were determined. The initial level of resistance and the mutation frequencies observed for the mono-resistant mutants were comparable to those previously reported. Targeted gene sequencing revealed the presence of known and clinically relevant mutations in the mutants resistant to linezolid, rifampicin, kanamycin and moxifloxacin. Significant growth defects were observed for mutants grown under in vitro conditions compared to the sensitive progenitor. Mutation frequencies determination in the mono-resistant mutants revealed a significant increase in mutation frequency against rifampicin and kanamycin, but a significant decrease in mutation frequency against linezolid and sutezolid. This suggests that these mono-resistant mutants are more prone to develop resistance to rifampicin and kanamycin, but less prone to develop resistance against linezolid and sutezolid. Even though kanamycin and linezolid both inhibit protein synthesis, these compounds target different subunits of the ribosome, thereby leading to different outcomes in terms of fitness in the mutants with impaired cellular function. These observations showed that oxazolidinone treatment is instrumental in limiting the development of multi-drug resistance in M. tuberculosis in vitro.

Keywords: oxazolidinones, mutations, resistance, tuberculosis

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Authors: Stacey Herzog, Mitchell McCleary, Istvan Kovacs

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Purpose: Maximal strength and maximal power are key athletic abilities in many sports disciplines. In recent years, velocity-based training (VBT) with a relatively high 75-85% 1RM resistance has been popularized in preparation for powerlifting and various other sports. The purpose of this study was to discover differences between beginner/intermediate and advanced lifters’ push/press performances after a heavy resistance-based BP training program. Methods: A six-week, three-workouts per week program was administered to 52 young, physically active adults (age: 22.4±5.1; 12 female). The majority of the participants (84.6%) had prior experience in bench pressing. Typical workouts began with BP using 75-95% 1RM in the 1-5 repetition range. The sets in the lower part of the range (75-80% 1RM) were performed with velocity-focus as well. The BP sets were followed by seated dumbbell presses and six additional upper-body assistance exercises. Pre- and post-tests were conducted on five test exercises: one-repetition maximum BP (1RM), calculated relative strength index: BP/BW (RSI), four-repetition maximal-effort dynamic BP for peak concentric velocity with 80% 1RM (4RV), 4-repetition ballistic pushups (BPU) for height (4PU), and seated medicine ball toss for distance (MBT). For analytic purposes, the participant group was divided into two subgroups: self-indicated beginner or intermediate initial resistance training status (BITS) [n=21, age: 21.9±3.6; 10 female] and advanced initial resistance training status (ATS) [n=31, age: 22.7±5.9; 2 female]. Pre- and post-test results were compared within subgroups. Results: Paired-sample t-tests indicated significant within-group improvements in all five test exercises in both groups (p < 0.05). BITS improved 18.1 lbs. (13.0%) in 1RM, 0.099 (12.8%) in RSI, 0.133 m/s (23.3%) in 4RV, 1.55 in. (27.1%) in BPU, and 1.00 ft. (5.8%) in MBT, while the ATS group improved 13.2 lbs. (5.7%) in 1RM, 0.071 (5.8%) in RSI, 0.051 m/s (9.1%) in 4RV, 1.20 in. (13.7%) in BPU, and 1.15 ft. (5.5%) in MBT. Conclusion: While the two training groups had different initial resistance training backgrounds, both showed significant improvements in all test exercises. As expected, the beginner/intermediate group displayed better relative improvements in four of the five test exercises. However, the medicine ball toss, which had the lightest resistance among the tests, showed similar relative improvements between the two groups. These findings relate to two important training principles: specificity and transfer. The ATS group had more specific experiences with heavy-resistance BP. Therefore, fewer improvements were detected in their test performances with heavy resistances. On the other hand, while the heavy resistance-based training transferred to increased power outcomes in light-resistance power exercises, the difference in the rate of improvement between the two groups disappeared. Practical applications: Based on initial training status, S&C coaches should expect different performance gains in maximal strength training-specific test exercises. However, the transfer from maximal strength to a non-training-specific performance category along the F-v curve continuum (i.e., light resistance and high velocity) might not depend on initial training status.

Keywords: exercise, power, resistance training, strength

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Authors: Inyeol Paik, Ah-Ryang Kim

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In this research, a statistical analysis is carried out to examine the statistical properties of the formula given in the design code for concrete structures. The design formulas of the Korea highway bridge design code - the limit state design method (KHBDC) which is the current national bridge design code and the design code for concrete structures by Korea Concrete Institute (KCI) are applied for the analysis. The safety levels provided by the strength formulas of the design codes are defined based on the probabilistic and statistical theory.KHBDC is a reliability-based design code. The load and resistance factors of this code were calibrated to attain the target reliability index. It is essential to define the statistical properties for the design formulas in this calibration process. In general, the statistical characteristics of a member strength are due to the following three factors. The first is due to the difference between the material strength of the actual construction and that used in the design calculation. The second is the difference between the actual dimensions of the constructed sections and those used in design calculation. The third is the difference between the strength of the actual member and the formula simplified for the design calculation. In this paper, the statistical study is focused on the third difference. The formulas for calculating the shear strength of concrete members are presented in different ways in KHBDC and KCI. In this study, the statistical properties of design formulas were obtained through comparison with the database which comprises the experimental results from the reference publications. The test specimen was either reinforced with the shear stirrup or not. For an applied database, the bias factor was about 1.12 and the coefficient of variation was about 0.18. By applying the statistical properties of the design formula to the reliability analysis, it is shown that the resistance factors of the current design codes satisfy the target reliability indexes of both codes. Also, the minimum resistance factors of the KHBDC which is written in the material resistance factor format and KCE which is in the member resistance format are obtained and the results are presented. A further research is underway to calibrate the resistance factors of the high strength and high-performance concrete design guide.

Keywords: concrete design code, reliability analysis, resistance factor, shear strength, statistical property

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Authors: Yavuz Yardım

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The most important criteria for structural engineering is the structure’s ability to carry intended loads safely. The key element of this ability is mathematical modeling of really loadings situation into a simple loads input to use in structure analysis and design. Amongst many different types of loads, the most challenging load is earthquake load. It is possible magnitude is unclear and timing is unknown. Therefore the concept of intended loads and safety have been built on experience of previous earthquake impact on the structures. Understanding and developing these concepts is achieved by investigating performance of the structures after real earthquakes. Damage after an earthquake provide results of thousands of full-scale structure test under a real seismic load. Thus, Earthquakes reveille all the weakness, mistakes and deficiencies of analysis, design rules and practice. This study deals with lesson learnt from earthquake recoded last two decades in Turkey. Results of investigation after several earthquakes exposes many deficiencies in structural detailing, inappropriate design, wrong architecture layout, and mainly mistake in construction practice.

Keywords: earthquake, seismic assessment, RC buildings, building performance

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Authors: Mehmet Fahri Sarac, Gokcen Akgun

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Ti–6Al–4V alloys are widely used in biomedical industries because of its attractive mechanical and physicochemical properties. However, they have poor wear resistance. High velocity oxygen fuel (HVOF) coatings were investigated as a way to improve the wear resistance of this alloy. In this paper, different mass ratio of Al₂O₃-TiO₂ powders (60/40, 87/13 and 97/3) was employed to enhance the tribological properties of Ti–6Al–4V. The tribological behavior was investigated by wear tests using ball-on-disc and pin-on-disc tribometer. The microstructures of the contact surfaces were determined by a scanning electron microscopy before and after the test to study the wear mechanism. Uncoated and coated surfaces after wear test are also subjected to micro-hardness tests. The tribological test results showed that the microhardness, friction and wear resistance of coated Ti-6Al-4V alloys increases by increasing TiO₂ content in the powder composite when other experimental conditions were constant. Finally, Al₂O₃-TiO₂ powder composites for the investigated conditions, both coating samples had satisfactory values of friction and wear resistance, and they could be suitable candidates for Ti–6Al–4V material.

Keywords: HVOF (High Velocity Oxygen Fuel), Al₂O₃-TiO₂, Ti-6Al-4V, tribology

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Authors: Ehsan Sadie

Abstract:

Today, after devastating earthquakes and many deaths due to the destruction of residential buildings, the scientific community has attracted the attention of the existing structures to strengthen and standardize construction. Due to the fact that the existing buildings are sometimes constructed without sufficient knowledge of the correct design, and even the buildings built according to the old standards today need to be reinforced due to changes in some provisions of the regulations. The location of some countries in the seismic zone has always caused a lot of human and economic damage throughout history, and attention to the strengthening of buildings, important facilities, and vital arteries is the result of this situation. Engineers' efforts to design earthquake-resistant buildings began when decades had passed since the development of design criteria and ensuring the safety of buildings against loads. New methods, mass reduction, reducing the weight of the building, use of moving structures to deal with earthquakes, as well as the use of new technologies in this field, including the use of dampers, composites in the reinforcement of structures are discussed, and appropriate solutions have been provided in each of the fields.

Keywords: brace, concrete structure, damper, earthquake, FRP reinforcement, lightweight material, retrofitting, seismic isolator, shear wall, steel structure

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Authors: Afnan Ahmad, Shahid Ali, Mujahid Khan

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This research presents the parametric study of an existing earth fill dam located at Latamber, Karak city, Pakistan. The study consists of carrying out seepage analysis, slope stability analysis, and Earthquake analysis of the dam for the existing dam geometry and do the same for modified geometry. Dams are massive as well as expensive hydraulic structure, therefore it needs proper attention. Additionally, this dam falls under zone 2B region of Pakistan, which is an earthquake-prone area and where ground accelerations range from 0.16g to 0.24g peak. So it should be deal with great care, as the failure of any dam can cause irreparable losses. Similarly, seepage as well as slope failure can also cause damages which can lead to failure of the dam. Therefore, keeping in view of the importance of dam construction and associated costs, our main focus is to carry out parametric study of newly constructed dam. GeoStudio software is used for this analysis in the study in which Seep/W is used for seepage analysis, Slope/w is used for Slope stability analysis and Quake/w is used for earthquake analysis. Based on the geometrical, hydrological and geotechnical data, Seepage and slope stability analysis of different proposed geometries of the dam are carried out along with the Seismic analysis. A rigorous analysis was carried out in 2-D limit equilibrium using finite element analysis. The seismic study began with the static analysis, continuing by the dynamic response analysis. The seismic analyses permitted evaluation of the overall patterns of the Latamber dam behavior in terms of displacements, stress, strain, and acceleration fields. Similarly, the seepage analysis allows evaluation of seepage through the foundation and embankment of the dam, while slope stability analysis estimates the factor of safety of the upstream and downstream of the dam. The results of the analysis demonstrate that among multiple geometries, Latamber dam is secure against seepage piping failure and slope stability (upstream and downstream) failure. Moreover, the dam is safe against any dynamic loading and no liquefaction has been observed while changing its geometry in permissible limits.

Keywords: earth-fill dam, finite element, liquefaction, seepage analysis

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