An analytical step-by-step procedure to derive the flexural response of RC sections in compression

This paper proposes an analysis procedure able to determine the flexural response of rectangular symmetrically reinforced concrete sections subjected to axial load and uniaxial bending. With respect to the usual numerical approaches, based on the fibre decomposition method, this procedure is based on the use of analytical expressions of the contributions to the equilibrium given by the longitudinal reinforcement and the concrete region in compression, which depend on the neutral axis depth and the curvature at each analysis step. The formulation is developed in dimensionless terms, after a preliminary definition of the geometrical and mechanical parameters involved, so that the results are valid for classes of RC sections. The constitutive laws of the materials include confinement effect on the concrete and postyielding behaviour of the steel reinforcement, which can be assumed to be softening behaviour for buckled reinforcing bars. The strength and curvature domains at the first yielding of the reinforcement in tension and at the ultimate state are derived in the form of analytical curves depending on the compression level; therefore, the role of a single parameter on the shape of these curves can easily be deduced. The procedure is validated by comparing some results with those numerically obtained by other authors. © 2013 Piero Colajanni et al

PBO textile embedded in FRCM for confinement of r.c. columns

Results of experimental tests on two reinforced concrete columns confined with PBO-FRCM jacketing subject to axial load and bending moments are presented, showing the effectiveness of the confinement system. Comparison of test results against theoretical results derived by a fiber model stress the ability of the confinement system to enhance both strength and deformation capacity of the confined concret

Analysis of local shear effects in brick masonry infilled RC frames

Masonry infills panels placed among framed structures meshes have a relevant influence in presence seismic actions in terms of strength stiffness and global displacement capacity. In the case of RC structures, the modifications of internal forces due to infill-frame interaction may be not compatible with surrounding frame members strength especially considering additional shear forces arising at the ends of beams and columns in contact with the panel under lateral actions. Such effects may be in many cases the cause of unexpected brittle collapse mechanisms which compromise the safety of the entire structure. In this paper by means of a double (micromodeling and macromodeling) procedure regarding RC meshes infilled with hollow brick masonry, a parametric study is provided defining a connection between local shear forces in critical frame regions and axial force on diagonal pin jointed strut. Proposed strategy allows to predict effective local shear forces using the simple macromodeling approach to reproduce the effect of masonry infills in models

Assessment of glycemic status and BMI of resident and non - resident female students of Jessore University of science and technology, Bangladesh

Background: Glycemic status means blood glucose level in an individual is measure by using the term hyperglycemia and hypoglycemia. Hyperglycemia is a condition in which an excessive amount of glucose circulates in the blood plasma whereas hypoglycemia is below normal level of glucose in blood.  Abnormal Glycemic status develops various short as well as long term health complications. Constant monitoring of health status of an individual’s is important in maintaining good glycemic status in preventing development of hyperglycemia and hypoglycemia related complication.Methods: Female students ages 20 – 23 of hall resident and non resident of Jessore University of Science and Technology were randomly selected. Fasting blood glucose data and Body Mass Index (BMI) were collected on the basis of family status, income and eating pattern, family environments using standard laboratory procedures.Results: The study found that 68% resident students were in hypoglycemic whereas 60% nonresident female students were in hypoglycemic but hyperglycemic and acute hyperglycemic effect was totally absent in both group of students. Differences of BMI irregularities of both groups of students were not observed. Most of residential students (88%) were only depends on the provided food in the dining hall. Whereas nonresident students majority of them are belonged to upper middle class, living in their own house and their eating patterns were better than residential female students. Therefore, most of the nonresident female students are able to intake nutritious foods. As a result the hypoglycemic students were found less abundant in nonresidential student compared to the resident group. Therefore dieting habit is one of the most important reasons to develop irregular glycemic status.Conclusions: The need of awareness of good health care practice, intake good quality nutritious diet, avoid of abnormal dieting practice is prerequisite to maintain static glycemic status which directly linked to good health

Strength and ductility of confined concrete columns under axial load and biaxial bending

The behaviour of prismatic reinforced concrete columns under increasing eccentric compression load was experimentally investigated and analytically modelled. Columns with distributed longitudinal reinforcement and closely spaced transverse reinforcement were tested up to failure, considering different values and directions of eccentricity. Preliminary tests were carried out under concentric compression in order to validate the choice of the stress-strain laws adopted for the confined concrete and the longitudinal steel bars in compression. In the paper, closed form expressions able to approximate the experimental results in the case of uniaxial bending are presented. Finally, a fibre numerical model is utilized for the cases of biaxial bending. The results show the reliability of the analytical models and suggest further studies to relate analytically the components of ultimate bending moment and curvature, in the cases of biaxial bending, to the values corresponding to two separate cases of uniaxial bending under the same level of compression.The behaviour of prismatic reinforced concrete columns under increasing eccentric compression load was experimentally investigated and analytically modelled. Columns with distributed longitudinal reinforcement and closely spaced transverse reinforcement were tested up to failure, considering different values and directions of eccentricity. Preliminary tests were carried out under concentric compression in order to validate the choice of the stress-strain laws adopted for the confined concrete and the longitudinal steel bars in compression. In the paper, closed form expressions able to approximate the experimental results in the case of uniaxial bending are presented. Finally, a fibre numerical model is utilized for the cases of biaxial bending. The results show the reliability of the analytical models and suggest further studies to relate analytically the components of ultimate bending moment and curvature, in the cases of biaxial bending, to the values corresponding to two separate cases of uniaxial bending under the same level of compression

Strutture intelaiate in c.a. con tamponamenti: Analisi degli effetti locali in presenza di azioni sismiche

La presenza di tamponamenti in muratura all’interno delle maglie di strutture intelaiate induce, in presenza di azioni laterali, una sostanziale modificazione della risposta globale rispetto a quella dei telai nudi in termini di rigidezza, resistenza e capacità di spostamento. Per le strutture in c.a. la variazione del regime di sollecitazione che si osserva sulle membrature che circoscrivono i tamponamenti può rivelarsi non compatibile con la resistenza di cui queste sono dotate. In particolare, l’insorgere di sforzi di taglio aggiuntivi alle estremità di pilastri, travi e, conseguentemente, nei nodi può eccedere le capacità resistenti di queste regioni, stimate in fase di progetto, causando meccanismi locali di rottura fragile. Attraverso una procedura di modellazione duplice (micromodellazione e macromodellazione) di maglie tamponate campione in c.a., viene proposto uno studio parametrico utile a definire uno strumento che, qualora si utilizzino modellazioni a puntone diagonale equivalente concentrico, consente di legare le sollecitazioni di taglio effettive nelle zone di contatto fra tamponamento e telaio al livello di sforzo normale assorbito dal puntone. Il criterio proposto consente quindi di adottare la modellazione più semplice per i tamponamenti, acquisendo comunque informazioni sugli effetti locali da essi prodott

KAJIAN PERUBAHAN PENGGUNAAN LAHAN DI KECAMATAN PAAL DUA KOTA MANADO

Perubahan penggunaan lahan besar-besaran terjadi di tiap-tiap wilayah administrasi Kota Manado yang mencakup beberapa kecamatan salah satunya yaitu Kecamatan Paal Dua, kecamatan Paal Dua adalah kecamatan yang resmi dimekarkan dari Kecamatan Tikala pada tahun 2012 yang lalu. Hal ini dikarenakan pertumbuhan dan perekembangan kota yang semakin hari semakin meningkat. Hal ini juga berdampak pada kebutuhan akan lahan, karena lahan tidak dapat bertambah, maka yang terjadi adalah penambahan guna lahan tertentu yang berakibat pada berkurangnya guna lahan lain di kecamatan Paal Dua itu sendiri. Berangkat dari hal tersebut maka dilakukanlah penelitian tentang perubahan penggunaan lahan di kecamatan Paal Dua Kota Manado yang difokuskan pada dua kelurahan yaitu kelurahan Malendeng dan kelurahan Paal Dua. Tujuan dari penelitian ini adalah 1Mengkaji intensitas perubahan penggunaan lahannya dan 2Mengetahui apa faktor – faktor yang mempengaruhi perubahan penggunaannya. Metode yang digunakan adalah metode penelitian deskriptif serta pendekatan kualitatif dan kuantitatif dengan melakukan wawancara dan interpretasi visual karakteristik yang tergambar pada peta citra satelit. Hasil penelitian menunjukan bahwa pada kelurahan Malendeng selama range waktu 12 tahun (2006-2018) mengalami peningkatan yang terbilang signifikan yaitu seluas 18,20 Ha (28%) daritotal luas lahan terbangun yang ada dengan perubahan guna lahan yang paling dominan yaitu perubahan lahan perkebunan menjadi lahan perumahan dengan luas 12,20 Ha. Kemudian untuk di kelurahan Paal Dua juga mengalami peningkatan yang terbilang signifikan yaitu seluas 25,22 Ha (26%) dari total luas lahan terbangun yang ada dengan perubahan gunalahan yang paling dominan yaitu perubahan lahan perkebunan menjadi lahan perumahan dengan luas 12,70 Ha. Faktor-faktor yang mempengaruhi yaitu terdiri atas faktor internal dan faktor eksternal. Faktor internal dipengaruhi oleh (1)Penduduk, (2)Kepemilikan lahan, (3)Aksesbilitas; kemudahan menjangkau lokasi usaha/tempat kerja & kemudahan menjangkau kawasan lain, (4)prasarana dan sarana, (5)Topografi; ketinggian lahan dan kemiringan lereng. Sedangkan faktor eksternal dipengaruhi oleh (1)Aturan/kebijakan pemerintah; rencana struktur ruang kota dan rencana pola ruang kota. Kata Kunci : Perubahan Penggunaan Lahan, Kecamatan Paal Du

Experimental Testing of Two Novel Stress Sensors for SHM of Masonry Structures

The paper presents an experimental study on the performance of two types of stress sensor for their possible use in structural health monitoring (SHM) of masonry constructions. Ceramic piezoelectric sensors and capacitive sensors were installed in mortar bed-joints of two series of masonry specimens made of calcarenite stones and clay bricks. The specimens were tested under uniaxial compression, assessing the effectiveness of the sensors in recording the stress state variation in terms of vertical stresses within different types of masonry. Experimental results show that, although both the ceramic and capacitive sensors were initially designed to be embedded in concrete elements, their application in mortar joints ensures a good agreement with records by standard measurement devices. Results also demonstrate the possibility to extend the application of these devices to existing masonry structures, where SHM becomes a challenging issue