Three-dimensional non-linear finite element analysis of reinforced concrete beams in torsion. Reinforced concrete members under torsion and bending are analysed up to failure. A non-linear concrete model for general states of stress including compressive strength degradation due to cracking is described.

This thesis describes a non-linear finite element model suitable for the analysis of reinforced concrete, or steel, structures under general three-dimensional states of loading. The 20 noded isoparametric brick element has been used to model the concrete and reinforcing bars are idealised as axial members embedded within the concrete elements. The compressive behaviour of concrete is simulated by an elasto-plastic work hardening model followed by a perfectly plastic plateau which is terminated at the onset the . crushing. In tension, a smeared crack model with fixed orthogonal cracks has been used with the inclusion of models for the retained post-cracking stress and the reduced shear modulus. The non-linear equations of equilibrium have been solved using an incremental-iterative technique operating under load control. The solution algorithms used are the standard and the modified Newton-Raphson methods. Line searches have been implemented to accelerate convergence. The numerical integration has been generally carried out using 15 point Gaussian type rules. Results of a study to investigate the performance of these rules show that the 15 point rules are accurate and computationally efficient compared with the 27(3X3X3) point Gaussian rule. The three- dimensional finite element model has been used to investigate the problem of elasto-plastic torsion of homogeneous members. The accuracy of the finite element solutions obtained for beams of different cross-sections subjected to pure and warping torsion have been assessed by comparing them with the available exact or approximate analytical solutions. Because the present work is devoted towards the analysis of reinforced concrete members which fail in shear or torsional modes, the computer program incorporates three models to account for the degradation in the compressive strength of concrete due to presence of tensile straining of transverse reinforcement. The numerical solutions obtained for reinforced concrete panels under pure shear and beams in torsion and combined torsion and bending reveal that the inclusion of a model for reducing the compressive strength of cracked concrete can significantly improve the correlation of the predicted post-cracking stiffness and the computed ultimate loads with the experimental results. Parametric studies to investigate the effects of some important material and solution parameters have been carried out. It is concluded that in the presence of a compression strength reduction model, the tension-stiffening parameters required for reinforced concrete members under torsion should be similar to those used for members in which bending dominates.The scholarship of the Ministry of Higher Education of the Republic of Iraq

Elevated temperature strain gages

The objective is to study the electrical resistance of materials that are potentially useful as resistance strain gages at 1000 C. A set of criteria were set and used to select strain gage candidate materials that are electrically stable and reproducible at all temperatures up to 1000 C. For the experimental phase of this research, the electrical resistance change with temperature of three groups of materials (solid solution alloys, transition metal carbides, and semiconductors) were studied with the intention of identifying materials with low temperature coefficient of resistance and low resistance drift rate at 1000 C. A preliminary study of the gage factor on one of the best candidate materials, B sub 4 C, was also undertaken. The results of these investigations are presented

Role of Serum Creatinine Phosphokinase in Outcome Prediction of Intoxicated Patients; a Brief Report

Introduction: Several mechanisms were introduced as causes of serum creatinine phosphokinase (CPK) raise in intoxicated patients. This study aimed to assess the relationship between serum CPK level in the first 24 hours and baseline characteristics as well as outcomes of these patients.Methods: This one year retrospective cross-sectional study was conducted on all intoxicated patients, who were admitted to a referral toxicology center, Northwest of Iran, stayed for at least 24 hours and had serum CPK level more than 500 IU/L in the first 24 hours of admission. The relationship between serum CPK level and some baseline and outcome variables were studied using SPSS version 21.Results: 413 patients with the mean age of 34.52 ± 15.24 years were studied (78.7% male). The mean CPK level at the time of presentation to ED was 3702.85 ± 6375.29 IU/L. There was not any significant relationship between presenting CPK level and type of poisoning (p = 0.258), sex (p = 0.587), and age (p = 0.817). The area under the ROC curve of CPK in prediction of need for dialysis, need for intensive care unit (ICU) admission, and mortality was 0.67 (95% CI: 0.57 – 0.77), 0.60 (95% CI: 0.52 – 0.69), and 0.60 (95% CI: 0.51 – 0.68), respectively.Conclusion: Based on the finding of present study, there was no significant association between serum CPK level in the first 24 hours and age, sex, and type of poisoning of  intoxicated patients and it had poor accuracy in prediction of their need to do dialysis, need for ICU admission, and mortality

CONFINEMENT AND EXPANSION MODELS FOR NONLINEAR ANALYSIS OF REINFORCED CONCRETE MEMBERS

This research pertains to expand the formulation and applicability of using confinement and expansion due to Poisson’s ratio models for three dimensional non-linear finite element analysis of reinforced concrete members. A plasticity based model that acknowledges the asymmetric response of reinforced concrete under multiaxial stress conditions is used to account for the strength improvement under conditions of triaxial compression. Complex behavior of concrete such as compression softening and tension softening are incorporated to simulate concrete behavior. DIANA software is used for finite element analysis with the inclusion of confinement and expansion effects. The concept of material pre-strains is extended to accommodate modeling of the Poison’s ratio effect. The applicability of the suggested confinement and expansion models are verified by comparing the results of Kupfer and Vecchio – Collins tests on shear panels with that obtained from DIANA software. These comparisons illustrate the ability of the confinement and expansion models to obtain the response of reinforced concrete members subjected to multiaxial stress conditions

Experimental Investigation of Shear- Critical Reactive Powder Concrete Beams without Web Reinforcement

جرت عملیة استقصاء عملی على سلوک عتبات خرسانیة عالیة المقاومة مصنوعة من المساحیق الفعالة. خمسة عشرة عتبة تحوی حدید تسلیح طولی تم صبھا وخالیة من تسلیح القص. المتغیرات الرئیسیة التی تم دراستھا ھی محتوى الالیاف الفولاذیة, نسبة حدید التسلیح الطولی, نسبة فضاء القص الى العمق الفعال ومحتوى السلیکا الفعالة. اعلى قیمھ لمقاومة الانضغاط کانت 110 میکاباسکال باستعمال نوع واحد من الالیاف الفولاذیة. تم اقتراح علاقات للتنبؤ بمقاومة اجھاد القص لعتبات خرسانة المساحیق الفعالة الخالیة من تسلیح القص. العلاقات االمقترحة اظھرت تطابقا جیدا لمقاومة اجھاد القص بالمقارنة مع النتائج العملیة

Compressive Strength of Lightweight Porcelanite Aggregate Concrete -New Formulas

From the various kinds of concrete, lightweight concrete (LWC) is one of the most interesting subjects for researchers because of its advantages such as the savings in concrete member size, reinforcement, formwork and scaffolding , foundation costs as well as the savings derived from the reduced cost of transport and erection. The reduction of dead load due to a lower density of concrete allows for smaller and lighterweight structural members. Reductions in the dimensions of columns and beams result in more available space, and reductions in their selfweight can improve the seismic resistance capacity of building structures. Furthermore, better fire resistance, heat insulation, sound absorption, frost resistance, and increased damping are other advantages of lightweight concrete. Lightweight aggregate concrete (LWAC) is not new in concrete technology; it has been used since ancient times. The fact that some of these structures are still in good condition validates the durability of concrete. The paper presents the results of testing 30 specimens (15 cylinders and 15 cubes) according to ASTM for determining the mechanical properties of sand lightweight aggregate concrete (SLWAC)made from Porcelanite (as a natural local material). The paper further presents new empirical predicted formulas for cylinder compressive strength, cube compressive strength; and relationship between them

Effect of Steel Fiber on The Behavior of Deep Beams With and Without Web Opening

This study investigates experimentally the strengthening of reinforced concrete deep beams using steel fibers. The experimental work could be divided in two parts, the first part consists of casting and testing six deep beams without web opening and the second part consists of casting and testing six deep beams with web openings to show the effect of volume of steel fibers on the behavior of the deep beams with and without web opening on ultimate load, deflection, with various shear span to depth (a/d) ratios [variable of clear shear span].On the other hand, the effects of these parameters on the behavior and capability of deep beams with constant steel fiber – volume fraction are obtained by using three groups of beams having steel fiber– volume fractions of 0.0%, 0.5%, 1.0% and studying the effect of the presence of steel fibers in deep beams with web openings. The results obtained from the experimental work [solid deep beams and deep beams with web openings], demonstrate that when the steel fiber volume- fraction is increased, the ultimate loads are also increased. The effect of steel fibers increases as the (a/d) ratio is decreased. In addition, the experimental work on deep beams without web opening showed that when the steel fiber volume-fraction is kept constant, the ultimate loads are increased as the (a/d) ratio is decreased. On the other hand, the percentages of increase in ultimate loads become higher as the steel fiber volumefraction is increased from 0.0% to 0.5% and 1.0%. However, the effect of decreasing the (a/d) ratio on the ultimate and cracking loads of the deep beams with web openings was not significant

Nonlinear Finite Element Analysis of RPC Beams Failing in Shear

Reactive powder concrete (RPC) is a new type of ultra-high strength and high ductility concrete first developed in the 1990's in France. It is recognized as a revolutionary material that provides a combination of ductility, durability, and high strength. In this research work the nonlinear f ini t e element investigation on the behavior of RPC beams is presented. This investigation is carried out in order to get a better understanding of their behavior throughout the entire loading history. Also, a numerical parametric study was carried out on the RPC beams to investigate the influence of fibrous concrete compressive strength ( ) cf f ¢ , tensile reinforcement ratio ( ) w r , fiber content ( Vf ) and shear span to effective depth ratio (a/d) on the shear behavior and ultimate load capacity of these beams. The three- dimensional 20-node brick elements are used to model the concrete, while the reinforcing bars are modeled as axial members embedded within the concrete brick elements. The compressive behavior of concrete is simulated by an elastic-plastic work-hardening model followed by a perfectly plastic response, which terminated at the onset of crushing. In tension, a fixed smeared crack model has been used