DEFLECTION
Deflection is the distortion or movement of a structure and its elements, such as trusses and beams, from their original positions. It is as significant for a designer to regulate deflections and strains as it is to recognize the stresses due to loads.
The practice of the ACI Code requirements, taking into account the non-linear relationship between stress and strain in concrete, has resulted in significantly smaller sections than those by the elastic theory. The ACI Code, also recognizes the use of steel up to a yield strength of 80 ksi and the use of high-strength concrete for structures. The practice of high-strength concrete and steel results in relatively smaller sections and a decrease in the toughness of the flexural member
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1. Instantaneous Deflection
The deflection of structural elements is mainly due to the dead load combined with a fraction of or whole of the live load. The deflection that happens immediately upon the application of the load is called the instantaneous or immediate deflection.
Its calculations are based primarily on the elastic behavior of the flexural members. The deflection ∆, is a function of the span, L, load, W, modulus of elasticity of the material, E and moment of inertia, I:
∆= f (WL/EI) = α (WL³/EI) = K (ML²/EI)
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Long-Time Deflection
Deflection of RC members continues to increase under the action of constant load, though very slowly with respect to time. Creep and Shrinkage are the major causes of this additional deflection, known as long-time deflection. This type of deflection is mainly influenced by humidity, temperature, curing time period, quantity of compression steel, and degree of the load. The ACI Code, Section 9.5.2.5, recommends that the long-term deflection for both lightweight and normal type of concrete flexural members can be found by λ= ζ
Rigid body motion does not change the length of a vector joining the pair of points inside the body and has no concern with the strain analysis. When external forces are applied on an elastic body, the body undergoes deformation. Due to the elasticity of the body, there comes into play a force which resists the deformation. This force is called stress force. Clearly, the deformation of the body is accompanied by the stress force. In other words, stress and strain occur together in inelastic body. There are two types of elastic deformation: (i) Dilatation and (ii) Shear strain set up in the body in such a way that there is a change only in volume but no change in shape, is called dilatation. In the shear deformation, there is a change in the shape of the body without a change in its volume. Dilatations are further categorized into two kinds: compression, in which volume is reduced; and rarefaction, in which the volume is
In the line of police work there is great discretion that is given. With discretion there is great power, and within that power is the ability to take someone’s life. Police officers are allowed to take one’s life if there is danger to one’s self, the surrounding community and depending on the severity of the situation at hand. All three of three circumstances are continually being calculated by the police officer. Police are trained to deal with use of force and deadly force through a one-plus-one method. The method tells the officers that in all situations that their intensity has to be one step or notch ahead of suspect. The intensity can be through vocal presence or keeping a higher degree of physicality. This can all be presented through what is called the force continuum.
The usage of concrete was explored by the Early Christian and Roman architects but fell out of use throughout the Middle Ages and Renaissance period. The material was only fully explored again in the later half of the 19th century but only for mundane purposes where the material was cheap, easy to work with, and versatile, but most importantly it’s fireproof characteristic. In 1870, the idea of reinforcing the concrete was born; steel rods were to be inserted to increase its strength. Taking this principle, Ernest Ransome (America) and Francois Hennebique (France) both developed frame systems. From this, open plan workspaces with large windows were created and it was proved to be well accommodated where fire had previously been a danger. Hennebique’s system used slim vertical posts, thin parallel beams on brackets and floor slabs; this resulted somewhat like a timber frame. Concrete was one of the most flexible materials and one with a least determining form. Concrete relied on its mould and the intelligence of its designer to give it aesthetic qualities for one to appreciate it. This became much more obvious when the architects of the last 19th century attempted to discover a style based on this material.
The transfer will govern the design, with decompression in service. It was found that eliminating small detachment of the tendons by using reinforcement in the top of the beam, resulted in savings. Another approach using strands near the top, but low enough that decompression requirement is achieved with a transfer, would limit the top stress
The structural torsional stiffness is calculated through finding the torque applied to the handle and dividing it by the angular deflection of the handle that is resulted from the torsional loading. It is expressed in term of Nm/degree of angular deflection. This calculation is shown below in figure 3.1
The materials used for the construction of the designed plan is steel of grade415 and to that for coloums and beams is concrete where grade of concrete for coloums is M40 and for beams is M30.
Dead loads are the weight of the building and the items that are permanently attached or built into the building. In buildings of the past dead load was piled into the building without thought of any consequence. However, designers now consider every once that is placed into the building. Dead load is often increased during the alteration of a building (Brannigan & Corbett, 2015). Dead loads can greatly affect the strategy and tactics of a department. As the building is damaged by fire, an increased dead load can increase the risk for collapse causing an increase risk for injury and death of personnel operating at the scene.
In this report, we will introduce and illustrate on precast concrete, pre-stressed concrete, ready-mix concrete, reinforced concrete, terrazzo and Urbanite in details.
For its realization, it was required to construct two cantilever thick concrete sections hanging from each abutment. In this case, two deficiencies with regard to reinforcement design were identified: improper detailing of rebars and absence of shear reinforcement in the middle of the concrete section, the later though was not required by the code of practice at that time. Therefore, improper detailing that caused the concentration of numerous bars in the same plane created a plane of weakness, which any cracks developing from it couldn’t be intercepted due to the absence of any shear reinforcement bars in the middle of the concrete slab. As a result, the bridge lost its ductility and was destined to a sudden crushing failure that prohibited any precautionary measures. (Johnson G. ,
In Flack’s piece "Wheel of Fortune", a painting that is almost photo like, but still looks so vibrant, so full of life almost as if the painting is in motion. To me this painting represents a cycle of life. Even though this piece being so colorful and full of life, which easy to get distracted by. The first thing I noticed as I started to deeply analyze this picture is the skull. Which usually symbolizes death, then I thought about the inevitable true about death. Some day we are all going to die whether you like it or not. You cannot hide or run from it no matter what you do. Death sits and waits for you with its cold and daunting hands. I have learned and accepted the fact that one day I’m going to die. The next thing that caught my attention
To what extent do the provisions of the EU Charter of Fundamental Rights have direct effect? Answer with reference to the court’s case law The aim of this essay is to explore the extent to which the provisions of the EU Charter of Fundamental Rights have direct effect. The first section will provide a definition of direct effect as a basic principal and elaborate on vertical and horizontal, direct effect with the use of case law. The second section will review the supremacy of EU law and highlight scope of direct effect.
A reflex pathway, or a reflex arc, is a neural pathway that is involved in the activation of a reflex. Reflexes are reactions that respond to stimuli. They usually happen without the sensory neurons having to pass directly through the brain. Therefore, reflexes are called involuntary reactions since they happen without a command. This allows the reflex action to occur quickly because the electrical signal can be sent to the spinal cord immediately without needing to go through the brain. The brain receives sensory input as the action occurs, but not before. The human body has lots of reflex pathways. However, if a disruption occurs in these pathways, the person most likely has a certain kind of neurological disorder that will make the person
bending, shear, axial and torsional shear. This type of structure has been used by engineers throughout
Manipulative material approach. According to Sousa (2013) utilizing manipulative materials allows children to break away from the traditional classroom setting and instructional style. Using manipulative materials can be exciting and motivating to students, naturally leading toward a greater interest in the intended use of the manipulatives and the learning activity. In addition in the study of Garrity (1998) as cited by Hunt et. al.
Experimental Mechanics involves the experimental investigations of the static and dynamic response of structures and machines, and in the development of improved techniques to obtain and analyze experimental data.