Structural Reviewer Part 2

A continuous beam is a beam that extends over more than 2 supports, which helps to develop greater rigidity and smaller moments compared to a series of simple beams with similar spans and loading. By having multiple supports, the beam can distribute the load more evenly, reducing the bending moments and increasing its overall stability. This makes continuous beams suitable for longer spans and heavier loads, as they can better withstand the forces acting upon them.

A cantilever beam is a projecting beam that is supported at only one fixed end. It is a type of beam that extends horizontally from a support structure, with the other end free to move. This type of beam is commonly used in construction and engineering to create overhangs or to support structures where one end needs to be fixed while the other end is free.

Elasticity is the property of a material that allows it to deform when a force is applied and then return to its original shape and size when the force is removed. This means that the material can stretch or compress under stress, but it will not permanently change its shape or size. Malleability refers to a material's ability to be easily shaped or formed by hammering or rolling. Toughness is the ability of a material to resist breaking or fracturing under stress. Ductility is the property of a material to be stretched into a wire without breaking.

The yield point is the stress at which a material begins to exhibit permanent deformation without any increase in load. It is the point at which the material transitions from elastic behavior to plastic behavior. At the yield point, the material has reached its maximum strength and any further increase in stress will result in permanent deformation. This is different from the proportional limit, which is the point at which the material behaves elastically and deformation is directly proportional to the applied load. The ultimate strength is the maximum stress a material can withstand before failure, and the elastic limit is the maximum stress at which a material can be stressed and still return to its original shape when the load is removed.

An axial force refers to a tensile or compressive force that is applied along the longitudinal axis of a structural member. This force acts through the centroid of the cross section, resulting in axial stress without any bending, torsion, or shear. In other words, the force is directly applied in a straight line along the length of the member, causing it to either stretch or compress. This type of force is also commonly known as an axial load.

Tension refers to the act of stretching or being pulled apart, causing the elongation of an elastic body. It is a force that acts in opposite directions and stretches or pulls an object. In contrast, compression refers to the act of pressing or squeezing an object, resulting in its shortening or reduction in size. Stress, on the other hand, is the force per unit area that is applied to an object, causing deformation. While force is a general term for a push or pull, tension specifically refers to the stretching or pulling apart of an object.

A simple beam is a beam that is supported on simple supports at both ends, which are free to rotate and have no moment resistance. This means that the beam can freely rotate at both ends and does not have any resistance to bending moments.

A stress-strain diagram is a graphic representation that shows the relationship between unit stress values and the corresponding unit strains for a specific material. It provides valuable information about the material's behavior under tension, including its elastic and plastic deformation properties, as well as its ultimate strength. The diagram typically consists of a linear elastic region, where stress and strain are directly proportional, followed by a yield point and a plastic deformation region. The stress-strain diagram is widely used in engineering to analyze and design structures and materials.

Shear is the correct answer because it refers to the lateral deformation that occurs when an external force causes one part of a body to slide relative to an adjacent part in a direction parallel to their plane contact. This type of deformation is commonly seen in materials like metal or concrete when subjected to forces that cause them to slide or deform sideways. Shear stress and shear strain are used to measure and quantify this type of deformation in materials.

The given correct answer is "Allowable stress". Allowable stress refers to the maximum unit stress that is permitted for a material in the design of a structural member. It is also known as working stress or maximum unit stress. This stress limit ensures that the material does not exceed its capacity and remains within a safe range to prevent failure or deformation. By considering the properties and characteristics of the material, engineers determine the allowable stress to ensure the structural integrity and safety of the member.

Compressive strain refers to the reduction in length of a material when subjected to compressive stress. When a material is compressed, it experiences a decrease in length due to the applied force. This phenomenon is known as compressive strain. It is the opposite of tension, where a material elongates under tensile stress. Therefore, the given answer correctly identifies the term that describes the shortening of a unit length of material produced by compressive stress.

Ultimate Strength refers to the maximum stress that a material can withstand before it fails or ruptures. It represents the point at which the material experiences complete failure and is unable to bear any further load. Unlike the yield point, elastic limit, and proportional limit, the ultimate strength is not a measure of the material's ability to return to its original shape after the stress is removed. Instead, it indicates the maximum stress that the material can sustain before breaking, making it a critical factor in determining the material's overall strength and durability.

An overhanging beam refers to a type of beam that extends beyond one of its supports. This design reduces the positive moment (bending) at the midspan of the beam, while creating a negative moment (opposite bending) at the base of the cantilever over the support. This configuration allows the beam to distribute the load more effectively and provides stability to the structure. Therefore, the answer "Overhanging beam" is the correct choice based on the given explanation.

The correct answer is 0.60 fy. This means that for BOX type and TABULAR textural members that meet the non compact section requirements of section 502.6, the allowable bending stress is 0.60 times the yield strength (fy) of the material.

The correct answer is 200mm. The ratio L/r for lacing bars arranged in a DOUBLE system should not exceed 200mm. This means that the length of the lacing bar (L) should not be more than 200 times its radius (r). This restriction ensures that the lacing bars are strong enough to provide adequate support and prevent any failure or collapse.

Toughness refers to the property of a material that allows it to absorb energy before rupturing. It indicates the ability of a material to withstand impact or shock without breaking or fracturing. A tough material can deform and absorb a significant amount of energy before reaching its breaking point. This property is important in various applications, such as in engineering and construction, where materials need to withstand high stress and impact forces.

The correct answer is 140mm because the ratio L/r for lacing bars arranged in a SINGLE system should not exceed this value.

The strength reduction factor for axial tension and axial tension with flexure is 0.90. This factor is used to reduce the nominal strength of a member to account for uncertainties and potential variations in material properties, construction practices, and loadings. It ensures a higher level of safety by reducing the design strength of the member.

Creep is the correct answer because it refers to the gradual deformation of a body caused by the continuous application of stress or prolonged exposure to heat. This process occurs over time and leads to a permanent change in the shape or structure of the material. Creep is commonly observed in materials such as metals, plastics, and geological formations, and it is influenced by factors such as temperature, stress level, and time.

The slenderness ratio L/r refers to the ratio of the length of a member to its radius of gyration. For members designed under compressive force, a lower slenderness ratio is preferred as it indicates a more compact and stable member. Therefore, a slenderness ratio of 200 is the most preferable option among the given choices.

Poisson's Ratio is the correct answer because it represents the ratio of lateral strain to the corresponding longitudinal strain in an elastic body under longitudinal stress. It is a fundamental property of materials that describes how they deform when subjected to stress. Poisson's Ratio is a dimensionless quantity and is always between -1 and 0.5 for most common materials. A value of 0.5 represents a material that does not change in lateral dimensions at all, while a negative value indicates that the material expands laterally when compressed longitudinally.

The strength reduction factor for axial compression and axial compression with flexure for spiral reinforcement is 0.75. This means that the strength of the structure is reduced by 25% when considering axial compression and axial compression with flexure and using spiral reinforcement. This reduction factor is important in determining the design and safety of the structure, as it accounts for the behavior of the spiral reinforcement under these loading conditions.

Ductility is the property of a material that allows it to undergo plastic deformation after being stressed beyond the elastic limit and before rupturing. This means that a ductile material can be stretched or drawn into a wire or thread without breaking. It is a measure of how easily a material can be deformed under tensile stress.

For members bent about their strong or weak axes, members with compact sections where the flanges are continuously connected to the web, the allowable bending stress is 0.66 fy.

The proportional limit is the maximum stress at which a material can be loaded and still return to its original length when the load is released. Beyond this point, the material will experience permanent deformation. The elastic limit refers to the maximum stress at which a material can be loaded and still return to its original shape after the load is released. The yield point is the stress at which a material starts to deform plastically. The ultimate strength is the maximum stress a material can withstand before it fails. Therefore, the best fit for the given explanation is the proportional limit.

The strength reduction factor for bearing on concrete is 0.70. This factor is used to reduce the ultimate bearing capacity of the concrete in structural design calculations. It takes into account various factors such as the type and condition of the concrete, the load duration, and the safety requirements. A reduction factor of 0.70 indicates that the ultimate bearing capacity of the concrete is reduced by 30% for design purposes.

The slenderness ratio L/r preferably should not exceed 300 for members whose design is based on tensile force. This means that the length of the member (L) should not be more than 300 times its radius of gyration (r). If the slenderness ratio exceeds this value, the member may become more prone to buckling or failure under tensile forces. Therefore, it is important to ensure that the slenderness ratio is kept below 300 to maintain the structural integrity of the member.

The strength reduction factor for axial compression and axial compression with flexure for tie reinforcement is 0.70. This factor represents the reduction in strength that is applied to the reinforcement when it is subjected to axial compression and flexure. It indicates that the tie reinforcement can withstand only 70% of its full strength when subjected to these combined forces.

Compressive stress refers to the stress that occurs when a force is applied to an object, causing it to be compressed or squeezed. In the context of an elastic body, when a compressive stress is applied, it creates an axial stress at the cross section of the body. This axial stress is developed to resist the compressive stress and prevent the body from collapsing or deforming under the applied force. Therefore, the correct answer is compressive stress.

The strength reduction factor for flexure without tension is 0.90. This factor is used to reduce the strength of a member or structure when it is subjected to bending without any tension. It accounts for the reduced capacity of the member in flexure due to factors such as cracking, deflection, and other limitations. By applying this reduction factor, the design ensures a more conservative and safe approach by considering the reduced strength in flexure without tension.

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