Building “three joints”: expansion joint, settlement joint and seismic joint. Have you made a clear distinction?


The “three joints” often used in construction engineering refer to: ① expansion joint (temperature joint), ② settlement joint and ③ anti vibration joint, also collectively referred to as deformation joint

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Due to the influence of temperature change, uneven foundation and earthquake, the deformation joint is easy to cause deformation or damage to the building

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Therefore, in the design, the house should be divided into several independent parts in advance, so that each part can change freely and independently

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This kind of joint is called deformation joint, including expansion joint (temperature joint), settlement joint and seismic joint

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·Indoor deformation joint, indoor ground deformation joint, indoor ground and cylindrical deformation joint treatment, deformation joint mosaic treatment, outdoor deformation joint, outdoor deformation joint, deformation joint with fine workmanship, proper installation and straightness, roof deformation joint, roof deformation joint, 1 expansion joint, when the building is long, the deformation joint is set to avoid cracks of structural components due to large thermal expansion and cold contraction of the building

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·The situations that need to set joints are as follows: (1) the length of the building exceeds a certain limit; (2) the plane of the building is complex and changes a lot; (3) the structural type of the building changes a lot

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·Setting principle: when setting expansion joint, it is usually to reserve a gap in the vertical direction along the length direction of the building at intervals of a certain distance or where the structure changes greatly, so as to disconnect all the building components above the foundation and divide them into independent parts that can expand freely in the horizontal direction

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Generally, the foundation part does not need to be disconnected because it is less affected by the temperature change

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·The maximum spacing of expansion joints shall be determined according to the structure of different materials

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See the maximum spacing of expansion joints of masonry structures and reinforced concrete structures in the code for design of concrete structures for details

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·The width of expansion joint is generally 20-40mm, usually 30mm

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·Other requirements in the structural treatment, brick structure can adopt single wall scheme, can also adopt double wall scheme; frame structure can adopt double column double beam scheme, can also adopt cantilever beam scheme

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① Wall expansion joint structure: the wall expansion joint is generally made in the form of flat joint

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When the wall thickness is more than 240mm, it can also be made into staggered joint, groove joint and other forms

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The external wall deformation joints are usually filled with elastic waterproofing materials such as hemp asphalt, foam plastic strip and ointment

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The seams are covered with galvanized iron sheets, colored steel sheets and other materials

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The deformation joints of interior walls are usually combined with wood seams and all kinds of metal plates for indoor decoration

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2

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Floor and floor expansion structure: the joints of floor and floor expansion joints are usually sealed with asphalt, foam plastic strip, ointment and so on

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The upper cover is metal, concrete or rubber plastic

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The structural treatment should meet the requirements of flat, smooth, waterproof and sanitary ground

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The expansion joint of the ceiling should be combined with the interior decoration

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Generally, the metal plate, wood plate or rubber plastic plate are used to cover the joint

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The joint cover plate can only be fixed on one side to ensure that the components on both sides of the joint can expand and deform freely in the horizontal direction

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③ Roof expansion joint structure: the roof expansion joint mainly has two positions: the same roof elevation on both sides of the expansion joint and the staggered roof height on both sides

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When the roof elevation on both sides of the expansion joint is the same and the roof is accessible, the waterproof ointment is usually used for caulking and flashing treatment; when the roof is not accessible, the half brick low wall is built on both sides of the joint to carry out roof waterproof and flashing treatment respectively The requirements are the same as roof waterproofing and flashing construction

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On the top of the low wall, the traditional method is to cover the seam with galvanized iron sheet

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In recent years, it is gradually popular to cover the seam with color steel sheet, aluminum sheet or even stainless steel sheet

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2

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Settlement joint is a kind of deformation joint which is set up to prevent uneven settlement and damage of buildings caused by different foundation bearing capacity or different loads

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·When joints are needed, ① when buildings are built on different foundations and it is difficult to ensure uniform settlement; ② when the foundation form, width and buried depth of adjacent parts of the same building differ greatly, it is easy to form uneven settlement; ③ when the height difference of adjacent parts of the same building is large (generally more than 10m), the load difference is great or the structural form changes greatly, etc When it is easy to cause uneven settlement; when the plane shape is more complex and the connection parts of each part are relatively weak; when it is between the original building and the new or expanded building

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·When setting settlement joints, the foundation, wall, floor, roof and other parts of the building must be disconnected in the vertical direction, so that each part can form an independent stiffness unit with its own free settlement

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·The settlement joint can also be used as expansion joint

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The width of settlement joint is related to foundation condition and building height

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① Structural treatment of foundation settlement joint: the foundation of settlement joint should also be disconnected, and its structural treatment can be divided into brick concrete structure and frame structure

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Strip foundation under brick concrete structure wall usually has three treatment forms: double wall eccentric foundation, cantilever beam foundation and column cross arrangement

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② Settlement joint structure of wall, floor and roof: galvanized iron sheet, aluminum alloy sheet and color steel sheet are commonly used to cover the settlement joint of wall; the cover joint treatment of settlement joint of floor, floor and roof is basically the same as that of expansion joint

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In order to reduce the influence of uneven settlement, the deformation direction should be fully considered

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In order to prevent the building from being damaged by the earthquake, the seismic joint is used to divide the building into several independent parts with simple shape and uniform structural stiffness, and the pre-set gap is used to reduce or prevent the collision of adjacent structural units caused by the earthquake

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·When the seismic fortification intensity is 7-9 degrees, the seismic fortification joints should be set in one of the following situations: ① the elevation difference of the adjacent buildings is greater than 6m; ② the buildings have staggered floors and the floor elevation difference is larger; ③ the stiffness and quality of the adjacent parts of the buildings are quite different

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·The width of the joint is generally 50-100 mm, but for multi-storey and high-rise reinforced concrete structure buildings, the minimum joint width should meet the following requirements: ① when the height is not more than 15 m, the joint width is 70 mm; ② when the height is more than 15 m, the joint width is increased according to different fortification intensity: in 6 degree area, the joint width is increased by 20 mm for every 5 m increase of the building; in 7 degree area, the joint width is increased by 20 mm for every 4 m increase of the building In the area of 8 degree, the joint width increases by 20 mm for every 3 m increase of the building; in the area of 9 degree, the joint width increases by 20 mm for every 2 m increase of the building

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The seismic joint should be set along the whole height of the building

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In general, the foundation can not be separated, but when the plane is complex, the foundation should also be separated

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Double walls or columns should be arranged on both sides of the joint to enhance the overall stiffness of the houses on both sides of the joint

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The structure of seismic joint in wall, floor and roof is basically the same as that of settlement joint

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In addition, it should be noted that the anti vibration joint should not be made into staggered joint, tongue and groove, so as to lose the function of anti vibration joint

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