STR-975: EFFECT OF SHEAR SPAN TO DEPTH RATIO ON SEISMIC PERFORMANCE OF REINFORCED MASONRY SHEAR WALLS

Over the past few decades there has been a substantial increase in the number of multi-story buildings constructed with reinforced masonry (RM). Similar to reinforced concrete (RC) buildings, shear walls are a popular lateral load resisting system in regions of high seismic activity due to its capability to provide lateral stiffness, strength and energy dissipation. One of the parameters that affects the inelastic behaviour and ductility of RM shear walls is the shear span to depth ratio, M/Vdv. This paper experimentally investigates the effect of M/Vdv on the seismic performance of RM shear walls that are dominated by diagonal shear failure. The experimental work involves two identical full-scale fully grouted rectangular RM shear walls, W-M/Vdv1.2 and W-M/Vdv1.8, tested under in-plane axial compressive stress and cyclic lateral excitations. Wall W-M/Vdv1.8 was subjected to a top moment so that M/Vdv was equal to 1.875, as compared to a value of 1.25 for wall W-M/Vdv1.2 that was tested without a top moment. Most of the existing design equations for nominal in-plane shear strength, Vn, for RM shear walls, including the current provisions of the Canadian Standards CSA S304-14, the Masonry Standards Joint Committee MSJC (2013), and the New Zealand code (2004) for masonry structures, limit the effect of the M/Vdv to an upper value of 1.0. The test results show a significant reduction of 25% in the shear strength when M/Vdv is increased, which means that limiting the effect of M/Vdv to an upper value of 1.0 is overestimating the Vn of RM shear walls at high values of M/Vdv. However, W-M/Vdv1.8 was able to achieve higher levels of displacement ductility. More results were analyzed and are presented in this paper according to force-based, displacement-based, and performance-based seismic design considerations

STR-976: EFFECT OF HORIZONTAL REINFORCEMENT ANCHORAGE END DETAIL ON SEISMIC PERFORMANCE OF REINFORCED MASONRY SHEAR WALLS

The most recent design codes for masonry structures necessitate the use of reinforced masonry (RM) shear walls in medium and high seismic areas. There are several factors that control the contribution of the horizontal reinforcement to the in-plane shear capacity of RM shear walls. One of these factors is its anchorage end detail. The current version of the Canadian Standards Association CSA S304-14 for design of masonry structures requires that the anchorage of the horizontal reinforcing bars in the plastic hinge region shall have a 90° or more standard hook at the ends of the wall. However, a 180° standard hook is required for ductile shear walls. On the other hand, some masonry design codes (e.g. New Zealand, NZS 4230:2004) permits a 90° anchorage hook for ductile walls. This paper discusses the results of three identical RM shear walls that were tested under in-plane axial compressive stress and cyclic lateral excitations. All the walls were dominated by shear failure before reaching their flexure capacity. Wall W-180° was constructed with a 180° hook while walls W-90° and W-Str had a 90° hook and straight bar. The test results show that a 180° hook is the most effective anchorage end detail in terms of lateral force capacity and ductility. However, wall W-Str reached a lateral resistance, Que, of 398 kN compared to 412 kN and 418 kN for walls W-90° and W-180°, respectively, with less than 5% difference. Moreover, wall W-180° achieved a high level of displacement ductility of 4.2 instead of 3.9 and 3.6 when using a 90° hook and straight bar at a drop in wall capacity to 80% of Que. More results are analyzed and presented in this paper according to force-based, displacement-based, and performance-based seismic design considerations

NDM-550: COMPREHENSIVE STUDY OF WIND-INDUCED TORSIONAL LOADS ON LOW- AND MEDIUM-RISE BUILDINGS

This paper summarizes the findings of extensive wind tunnel parametric investigations on wind-induced torsion acting on rectangular flat- and gable-roofed buildings. Experiments collected data for different configurations in terms of terrain exposure, wind direction and building height. In addition, wind load combinations (i.e. shear forces and torsion) in transverse and longitudinal building directions were examined. Comparisons with the results obtained from provisions specified in current design standards and codes of practice were also carried out. Three building models (scaled at 1:400) have the same horizontal dimensions (length = 61 m, width = 39 m) but with different gabled-roof angles (0o, 18.5o, and 45o). All building models were tested at different eave building heights (6, 12, 25, 30, 40, 50 and 60 m) in open and urban terrain exposures for different wind directions (every 15o). Figure 1 presents the three building models in addition to a schematic representative of external pressure distributions on building envelope at a certain instant, the exerted shear forces (FX, FY) and torsional moment (MT). The synchronized wind tunnel measurements are presented in terms of pressures, shear, and torsional coefficients

Investigating ‘Relevancy’ of the Traditional Principle of the Right of Appropriation of Open Space and Fina’ in Contemporary Urban Poor Communities in Cairo, Egypt

Many scholars have questioned ‘relevancy’ of the principles of traditional urbanism where contradictory discourses have accumulated over time especially during the past few decades but unfortunately without a reliving answer. This research is a humble attempt to question this relevancy in our modern time in the domain of urban poor communities in Cairo through investigation one of the essential traditional housing principles, namely, “the right of appropriation of open spaces and fina’”. A method of qualitative/quantitative work has been embraced in which first, the investigated principle was defined from various sources of literature, then, field investigations through multiple case studies were conducted to address the question of relevancy to the urban poor communities today. It has been found that the principle is relevant to the residents’ practices and significantly relevant to their attitudes. This opens the door for what might be considered as (re) legitimization of the principle, after considering its probable health and environmental impacts, through integrating it within the current social housing processes in Cairo and in Egypt as a whole

Performance Evaluation of IFAS System Using Honeycomb PVC Media

Recently, Egypt is facing serious problems caused by the deterioration of effluent quality of many wastewater treatment plants (WWTP) especially in rural areas. Unexpected rapid increase in population associated with the increase of organic loading are the main factors causing the failure in operation for many WWTPs. Absence of periodic maintenance and lack of operators’ experience in these rural areas make the situation worse. Many WWTP are recently under rehabilitation and upgrading for the above reasons, however decision makers are facing a real challenge due to the space-limit in many cases. The integrated fixed film activated sludge (IFAS) system has recently proved to be an effective choice to expand the WWTP capacity for growing communities, enhance nitrogen removal and comply with more stringent effluent limits with small footprint. In this research, an IFAS pilot-scale reactor is constructed to optimize its application in upgrading conventional activated sludge (CAS) plants. The effect of carrier position, hydraulic retention time (HRT) and organic loading rate (OLR) on the biological treatment efficiency and nutrient removal compared to CAS process are studied. IFAS configurations with no media, vertical position and cross flow media position are tested with 4, 8 and 12 hours retention times and organic loading rates of 0.84 and 1.44 Kg COD/m3.day. Keywords: Integrated fixed film IFAS, biological nitrogen removal, honeycomb PVC media DOI: 10.7176/CER/11-2-06 Publication date:March 31st 2019

Incidence and risk factors for surgical site infection post-gynecological operations in a tertiary hospital in Egypt: a retrospective study

Background: Surgical site infection (SSI) is the most common complication of surgical procedures in gynecology and it poses a significant burden for both patients and healthcare systems. Our objective was determining the incidence and risk factors for SSI post-gynecological operations during the period of five years.Methods: A matched case-control study at Minia maternity university, Egypt where A total of 18772 cases had undergone different gynecological procedures. The 876 cases were complicated with SSI (SSI cases group) and 2 matched controls per case were chosen from the rest of the cases and served as the control group (n=1752 cases).Results: The overall incidence of SSI post-gynecological operations was 4.67% and post-hysterectomy was 7.57%. SSI group had a significantly higher number of cases with diabetes, obesity, high parity (>4), increased blood loss and those had prolonged duration of surgery compared to the control group (all p<0.01).Conclusions: The identified risk factors are crucial for risk stratification of SSI and prioritizing interventions to improve the outcome. These results could give a picture for SSI post-gynecological operations in our country and identifying these risk factors is crucial for risk stratification of SSI and prioritizing interventions to improve the outcome

Remote sensing of endangered tree species in the fragmented Dukuduku Indigenous Forest of KwaZulu-Natal, South Africa.

Doctor of Philosophy in Environmental Sciences. University of KwaZulu-Natal, Pietermaritzburg, 2016.Abstract available in PDF file

EFFECT OF IRRIGATION SYSTEMS IMPROVEMENT ON WATER UNIT PRODUCTIVITY UNDER NORTH DELTA REGION CONDITIONS OF EGYPT

Several field trials and laboratory studies were conducted to evaluate the impact of the implementation of the activities and processes of the development of the field irrigation systems at ElMahmoudia area, El-Beheira Governorate, Egypt, during the successful growing seasons winter 2016/17 and summer 2017 to investigate the effect of irrigation systems improvement projects on water productivity. The measurements were conducted in a tertiary canal (Mesqa) at the head of Nekla canal (Arafa Mousa Mesqa). Water consumption values for different crops were calcaulated, and water application was calculated through calibrating the capacities of the pumps and recording the operation hours. The most important results were as follows: Applied irrigation water decreased after irrigation improvement. Applied irrigation water for wheat, rice, maize, sweet potatoes and watermelon before irrigation improvement were higher than the corresponding values after irrigation improvement by 9.0%, 15%, 11%, 15% and 10% respectively. The productivity of wheat, rice, maize, sweet potatoes and watermelon increased after irrigation improvement by 7.0%, 4.0%, 3.0%, 8.0% and 9.0% respectively. Water productivity increased after irrigation improvement, and the increase ratios for wheat, rice, maize, sweet potatoes were 14.0%, 16.0%, 13.0%, 20.0%, and 18.0% respectively

Initial Study for Cost-Effectiveness of Joint/Crack Sealing

The sealing and resealing of joints and cracks in PCC, HMA, and composite pavements is assumed to be an important component of pavement maintenance. Recently this practice has been challenged by research indicating that sealing may not be cost-effective. The Indiana Department of Transportation currently spends approximately four million dollars annually to perform joint/crack sealing. The primary objective of the research presented in this report is to investigate the costeffectiveness of joint/crack sealing in relation to pavement performance. The results of a mail survey showed that most states, including Indiana, do not have quantitative justification for sealing policies, nor do they know the cost-effectiveness of the operations. Based on the experimental design for this research, nineteen test sites were selected in Indiana, each site having one sealed section and one unsealed section. Collected data including falling weight deflectometer measurements, pavement roughness, visual condition surveys, and core samples were used to evaluate the pavement performance between sealed and unsealed sections. A three-dimensional finite element pavement model was developed to evaluate the test location effect on the load transfer measurements. The temperature effect was evaluated by statistical analyses and a temperature correction factor for deflections on asphalt pavement is provided. A statistical model was developed to compare the pavement performance between sealed and unsealed sections for three pavement types, PCC, HMA and composite. The results indicated that there appears to be no significant differences between the performance of sealed and unsealed sections regardless of pavement type, drainage condition and road classification