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Understanding Steel Failure in Civil Engineering Projects

Learn about the different modes of steel failure in civil engineering projects, including buckling, bearing, tensile, corrosion, and fatigue. Explore the properties and characteristics of steel and how they impact its performance.

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Understanding Steel Failure in Civil Engineering Projects

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  1. R1.3 RESP1.3 RESPONSE OF CIVIL ENGIONEEONSE OF CIVIL ENGINEERING PROJECT STEEL 1.3 RESPONSE OF CIVIL ENGINEERING PROJECT BY : NOR AZAH BINTI AZIZ

  2. Learning Outcomes: Identify and describe material response of modes primary failure due to: B) Steel i. Structure failure ● Buckling ● Bearing ● Tensile ii. Performance failure ● Corrosion ● Fatigue

  3. STEEL It’s included in the term ferrous metal It’s a combination of iron & carbon( 0.01 – 1%) Contains varying amounts of manganese, phosphorus, sulfur, silicon & 20 other alloys Alloys added to produce steel of different characteristics. To produce useful steel, pig iron need to be oxidized in another furnace at about 1650°C.

  4. STEEL Most steel is made by the basic oxygen process, electric-arc process, open-hearth process or vacuum process. Carbon is the key element in controlling the properties of ordinary steel called carbon steel.

  5. There are 2 main groups; 1. Mild Steel Tensile strength 250 N/mm2 used in steel work construction 2. High Strength Steel Tensile Strength 460 N/mm2 Used in pre-stressed concrete work, cable for suspension bridge n high tensile bolts. Notes: Applying for reinforcement in concrete structures and steel structures (civil and infrastructure) STEEL 5

  6. Steel Structure Failure ● Buckling ● Tensile ● Bearing

  7. Buckling In engineering, buckling is a failure mode characterized by a sudden failure of a structural member subjected to high compressive stresses. The actual compressive stress at the point of failure is less than the ultimate compressive stresses that the material is capable of withstanding.

  8. This mode of failure is also described as failure due to elastic instability. Mathematical analysis of buckling makes use of an axial load eccentricity that introduces a moment, which does not form part of the primary forces to which the member is subjected. Buckling

  9. Column Buckling Column

  10. Buckling (steel plate) Before After

  11. Tensile (or tension) is the stress state leading to expansion; that is, the length of a material or compression member tends to increase in the tensile direction. Tensile stress is the opposite ofcompressive stress. Structural members in direct tension are ropes, soil anchors and nails, bolts, etc. Tensile

  12. A tensile test, also known as tension test. By pulling on something, you will very quickly determine how the material will react to forces being applied in tension . As the material is being pulled, you will find its strength along with how much it will elongate. What is tensile Test

  13. As continuing to pull on the material until it breaks, complete tensile profile will be obtained. A curve will result showing how it reacted to the forces being applied. The point of failure is of much interest and is typically called its "Ultimate Strength“ or UTS on the chart. Why Perform a Tensile Test

  14. BEARING STRESS is The surface pressure acting on a joint face directly as a result of the force applied by a fastener. Bearing stress is the contact pressure between the separate bodies. It differs from compressive stress, as it is an internal stress caused by compressive forces Bearing Stress

  15. The equation to determine average bearing stress would be sigmab = P/A P= force applied A= contact area of the object resisting the force. SI unit is Newton/meter2 which equates to Pascals (Pa). Bearing Stress

  16. Bearing properties are used when designing mechanically fastened joints. The purpose of a bearing test is to determine the deformation of a hole as a function of the applied bearing stress. Bearing Properties

  17. Steel Performance Failure ● Corrosion ● Fatigue

  18. Corrosion is oxidation or combining of the iron with oxygen that occurs in the presence of moisture. Proceeds more rapidly where there is noticeable dampness but it occurs in any air with a relative humidity higher than 70%. Corrosion

  19. Corrosion occurs more rapidly in salt air and industrial atmosphere. The rust is formed from the solid metal, reducing it size so that the members become weaker and loses any decorative finishes it might have. Corrosion

  20. A metal component @ structure that is subjected to repeated or cyclic stresses may eventually fail, even though the maximum stress in any one stress cycle is considerably less than the fracture stress of the material. Fatigue

  21. A common occurrence, as components are subject to alternating @ fluctuating loads during their service life. Fatigue

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