DEFECTS
Syllabus - The study of various defects in buildings and their remedies, Defects caused by dampness, applied forces and changes in size.
STRUCTURAL DEFECTS
DEFINITION •
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Damage to the load-bearing portion of a building that affects the use of the structure for human purposes. Includes damage from shifting of soil due to earthquake, flood or other factors
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Makes a project dangerous, unsafe or causes real damage to the consumer. consumer.
Building defects affect society at large due to possible danger posed;
REASONS •
usually include any deficiency in the performing or furnishing of
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design,
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planning,
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supervision,
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inspection,
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construction
REASONS •
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Construction defects usually include any deficiency in the performing or furnishing of the design, planning, supervision, inspection,
WHAT ARE CONSTRUCTION DEFECTS •
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Defective building material or components-materials: i.e., inferior material such as building bricks, cement, roofing material, poorly manufactured windows A violation of Building Codes at the time of construction. Failure to meet professional standards for design at the time plans were approved. Design: i.e., faulty R.C.C. roofing design contributes to water intrusion Failure to build according to accepted trade standards for good and workman like construction. Workmanship: i.e., substandard or shoddy work Engineering/Soil: i.e., structural failures and earth movements
VERTICALITY
L A S R T U C T E C F U E R D T S
DESIGN DEFICIENCEIES
LINEARITY
MATERIAL DEFIECIENCIES
ANGULARITY
SUBSTANDARD WORKMANSHIP SUB-SURFACE OR GEO-TECHNICAL PROBLEMS
CRACKS IN THE BUILDING
Structural Cracks:These occur due to incorrect design, faulty construction or overloading and these may endanger the safety of a building. e.g. Extensive cracking in wall and beams.
Structural Damage Structural damage is probably the most expensive type of damage to repair. If not done properly, your house can collapse. Structural problems, though rare, are usually very expensive to repair.
Structural Damage
Floor joist cut to allow for heating duct. Structural integrity of the floor in danger.
Structural Damage Welding torch hole cut in steel beam in garage to facilitate the garage door opener.
Structural Damage Old pier with washed away footing and CMU blocks set on their sides.
Structural Damage Diagonal crack with multiple plane. Uneven settling, commonly seen in clay soil conditions. A real structural problem.
ELASTIC DEFORMATION: •
Structural components of a building undergo elastic deformation due to dead and the super imposed live loads.
ELASTIC DEFORMATION: •
Structural components of a building undergo elastic deformation due to dead and the super imposed live loads, in accordance with hook law. The amount of deformation depends upon elastic modulus, meningitides of loading and the dimension of the component. This elastic deformation under certain circumstances causes cracking in the building as under: •
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When walls are unevenly loaded with wide variations in stress in different parts, excessive shear stress is developed which causes cracking in walls. When a beam or slab of large span undergoes excessive deflection and there is not much vertical load above the supports (as in the case of roof slab), ends of beam / slab curl up causing cracks in supporting masonry. When two materials, having widely different elastic properties, are built side by side, under the effect of load, shear stresses are set up at the interface of the two materials, resulting in cracks at the junction. Such a situation is commonly encountered in the constructions of RCC framed structure and brick
ELASTIC DEFORMATION: •
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When walls are unevenly loaded with wide variations in stress in different parts, excessive shear stress is developed which causes cracking in walls. When a beam or slab of large span undergoes excessive deflection and there is not much vertical load above the supports (as in the case of roof slab), ends of beam / slab curl up causing cracks in supporting masonry. When two materials, having widely different elastic properties, are built side by side, under the effect of load, shear stresses are set up at the interface of the two materials, resulting in cracks at the junction. Such a situation is commonly encountered in the constructions of RCC framed structure and brick masonry panel (external) and partitions (internal) walls.
GIVE EG./PIC
GIVE EG.
ELASTIC DEFORMATION: •
Structural components of a building undergo elastic deformation due to dead and the super imposed live loads, in accordance with hook law. The amount of deformation depends upon elastic modulus, meningitides of loading and the dimension of the component. This elastic deformation under certain circumstances causes cracking in the building as under: •
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When walls are unevenly loaded with wide variations in stress in different parts, excessive shear stress is developed which causes cracking in walls. When a beam or slab of large span undergoes excessive deflection and there is not much vertical load above the supports (as in the case of roof slab), ends of beam / slab curl up causing cracks in supporting masonry. When two materials, having widely different elastic properties, are built side by side, under the effect of load, shear stresses are set up at the interface of the two materials, resulting in cracks at the junction. Such a situation is commonly encountered in the constructions of RCC framed structure and brick
Q. What are the causes for deterioration of RCC buildings?
1. Poor structural design and specifications 2. Poor quality of construction 3. Poor maintenance of buildings – e.g. 4. Environmental problems and aging effects – e.g. 5. Indiscriminate additions & alterations e.g.
1.Poor structural design & specifications -Densely spaced steel bars -Segregated concrete at beam column junction -Honey combing of concrete
2.Poor construction & overloading with illegal mezzanine floors
Poor Construction, Poor quality of materials used & poor supervision.
-Poor construction & neglected maintenance
Check for materials like cement,sand admixtures etc. -Proper mixing and batching of materials
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Silt & clay in sand
Excess water in mortar
3.Poor maintenance -Leaking roof -Spalling (breaking into small componenets) of Concrete due to corrosion
4- ENVIRONMENTAL CONDITIONS AROUND THE BUILDINGS, Chemicals like carbon-dioxide, chlorides, nitrous oxides, moisture and sulphates
5- OVERLOADING OF STRUCTURE OR WEAKENING ITS STRUCTURAL MEMBERS DUE TO ALTERATION/ RENOVATION.
-Chipping of defective or deteriorated concrete
Repairs by guniting/jacketing with concrete or treated with cement or polymer concrete
Roughened base coat of plaster for better mechanical bond with the finishing coat.
Curing by ponding water on horizontal surface
Curing by spraying water at regular intervals on vertical surface
To reduce cost :Check the locations where repairs are necessary and where repairs need not be done.
Removal of rust before repair using gunuiting Whole plaster is replaced.
Rusting of steel in RCC column on ground floor resulting in spalling of concrete
Cracks,crevics ,joints and junctions should be properly packed before repai
Cracks developed due to improper curing.
Failure due to modification
Building before repairs and after repairs
Corrosion of steel & spaulling of concrete due to ingress of moisture
-Cantilever canopy showing porous honeycombed concrete -Deteriorated cantilever balcony slabs
Spaulled concrete due to corrosion of steel by leakage
- Cracks over superficially repaired surface
- Corrosion of steel in RCC beam
5.Indiscriminate Addition & Alterations in Buildings Some DO’S & DON’TS
Alterations in Window balcony
Additions to window canopy
Conversion of balcony into dressing room
Conversion of balcony into a bath room
Adding waterfall & potted plants on balcony
Overloading the RCC building by installing large tanks
Careless modification causing damage to structure
Damaging RCC beam to conceal electric conduits & adding load by new floor tiles
Chamfering RCC columns in stilt area to avoid damage to cars
Removing RCC beams & columns between two flats
Removing RCC beam and part of RCC slab & Introducing additional staircase load to interconnect two flats
Introducing additional load on RCC slab & beam by relocating partition wall
6. Calamities of building failure -Earthquake -Floods -Terrorist attack -Bomb blast
