1, structural design description
It mainly includes design basis, seismic grade, civil air defense grade, foundation condition and bearing capacity, moistureproof and impermeability practices, live load value, material grade, matters needing attention in construction, details selection, general details or nodes, and information not drawn in construction drawings but expressed through explanations. For example, the alkali content of concrete shall not exceed 3kg/m3, etc.
2, the structural layout of each layer, including:
(1) Precast slab layout (slab selection, joint size, reinforcement). When marking the number and type of precast slabs, do not use inclined formwork. Because this method is easy to cause lines to cross, it is advisable to use horizontal or vertical lines to directly mark the room model of the same type. The whole building should be numbered uniformly, which can reduce the design workload and facilitate the construction personnel to look at the pictures. The slab joint should be 40 as far as possible, and this slab joint may or may not be reinforced. When paving the slab, spread it from indoor to outdoor, use wide slab as far as possible, leave the cast-in-place slab belt at the window, and the cast-in-place slab bandwidth is greater than or equal to 200 (consider riser passing through the slab for water heating). If the whole layer is required to be poured in the structure, the slab joint should be greater than 60. The thickness of the whole pouring layer is 50, with bidirectional φ6@250 and C20 concrete. Pure frame structure generally does not need to add integral pouring layer. Precast slabs shall not be laid at constructional columns. Due to fire protection requirements, prefabricated panels are not provided in the underground garage. Frame structure should not use long slab, otherwise the parallel joints between long slab and frame beam are prone to cracks. It is suggested to use the manual layout function of PMCAD to lay precast slabs. Automatic layout may not meet the requirements of the user's construction drawing, but only meet the requirements of defining the load transfer route. SP board is sensitive to the floor clear height, and can be used when the span exceeds 6.9 meters or does not meet the modulus. The thickness of SP plate is 120, and the span can reach 7.2m..
(2) Cast-in-place slab reinforcement (upper and lower reinforcement, thickness dimension). General plate thickness is 120, 140, 160, 180 or 120, 150, 180. Use secondary steel as much as possible, including secondary steel with a diameter of φ 10 (seldom used at present) and reinforced bars with a diameter ≥ 12. In addition to the hook, the main reinforcement shall not be used. The rebar diameter should be larger and the spacing should be larger, but the spacing should not be greater than 200 and the spacing should be 200. (Generally, plate cracks with a span less than 6.6m can meet the requirements). For slabs with a span of less than 2m, it is not necessary to disconnect the upper reinforcement, and the reinforcement can be omitted, which only means that the reinforcement is bidirectional and double-row φ8@200. The spacing between upper and lower steel bars on the plate should be equal, and the diameters can be different, but the types of steel bar diameters should not be too many. At the top floor and considering the crack resistance, the steel bars on the slab can be connected continuously or 50%, and the additional steel bars and pull-through steel bars in larger places should be overlapped by tensile steel bars. When the plate reinforcement is the same, just mark the plate number. Generally, plates with the same lower reinforcement and some upper reinforcement can be made into a plate number, and different upper reinforcement can be drawn on the drawing. When the plates have different shapes but the steel bars are the same, they can also be coded as plate numbers. It should be numbered uniformly throughout the building. When crossing the catheter, the thickness of the catheter should be ≥ 120, and the thin plate and cushion should not be used. For the plate at the outlet of the electric tube well, due to too many electric tubes, the plate thickness can be increased to 180 (considering the superposition of 4 layers of 32 steel tubes). It is advisable to use long-span slabs as far as possible, and rooms (especially houses) are not equipped with secondary beams. It shows that the distribution of reinforcement is φ6 @ 250, and the place with great temperature influence can be φ8 @ 200. When the elevation of the top of the plate is different, the upper reinforcement of the plate should pass separately or obliquely. Cast-in-place cantilever slab external angle plus radial additional reinforcement (including internal wall external angle). Inclined reinforcement should be added under the cast-in-place cantilever slab at the internal corner. On the top floor, it is suggested that Party A adopt cast-in-place floor slab, which is convenient for waterproofing, strengthening structural integrity and facilitating the stability of decorative overhangs. Exposed pick along, rain cover, pick gallery should be every 10 ~ 15 meters set a 10mm seam, steel bar constantly. Cast-in-place slab shall be adopted as far as possible, and the scheme of precast slab plus integral pouring layer shall not be adopted. The toilet practice can be 70 thick+10 height difference (cancel the cushion). Non-prestressed slabs can be used for slabs below 8 meters. The slab near the internal corner of the L, T or cross-shaped building plane should be cast-in-place and thickened, reinforced in two directions and double rows, and 4 tensile bars 16 should be attached in the direction of 45 degrees. It is suggested to use PMCAD software to automatically generate the reinforcement of cast-in-place slab, which can speed up the speed and reduce clerical errors. It is suggested that reinforcement numbers should not be compiled when automatically generating floor reinforcement, because hundreds of reinforcement numbers may be compiled when the project is large, which is difficult to find. If you need a number, you can't take out the room. When calculating reinforcement, the redistribution of plastic internal force can be considered. The upper reinforcement is multiplied by the reduction factor of 0.8~0.9, and the lower reinforcement is multiplied by the amplification factor of 1. 1~ 1.2. It is worth noting that the reinforcement of two-way slab calculated by elasticity is the maximum value in some places of the slab, so the reinforcement is conservative and does not need to be artificially enlarged. The negative reinforcement of the floor slab supported on the outer ring frame beam should not be too large, otherwise it will produce excessive additional torque to the beam. Generally: when the thickness is > 150, φ10 @ 200 is adopted; Otherwise, pay attention to the following points in the plate reinforcement diagram generated by φ8@200. PMCAD: 1。 One-way slab is calculated according to plasticity, and two-way slab is calculated according to elasticity, so it should be changed into a calculation method. 2. When connecting the thick plate with the thin plate, the thin plate bearing should be considered as the fixed end. If the thick plate is not suitable, the reinforcement of the thick plate bearing should be reduced and the reinforcement in the middle of the span should be increased. 3. Non-rectangular plates should reduce the load-bearing reinforcement and increase the mid-span reinforcement. 4. If there are too many rooms or concave plates, the finite element program should be used to check their reinforcement. The plate reinforcement diagram generated by PMCAD is PM? . T. Plates can generally be calculated according to plasticity, especially foundation plates and civil air defense structures. However, the structure is self-waterproof, and cracks are not allowed. For buildings with strict waterproof requirements, such as slopes, flat roofs, cabinets and toilets, power distribution rooms, etc., elastic calculation should be adopted. Generally, it is not advisable to thicken the steel bar under the indoor light partition wall. On the one hand, the light partition wall may be displaced, on the other hand, it is necessary to improve the overall stress of the floor. Only the partition wall perpendicular to the long side of the one-way slab can be thickened and cannot be displaced, such as the partition wall between the bathroom and other rooms. The sloping roof slab is a partial component and should be reinforced in two directions and double rows.
(3) About lintel arrangement and light partition wall. At present, the frame infilled wall is generally a light wall, and the lintel generally does not need precast concrete lintel, but cast-in-place beam belt. The practice and atlas of light wall, such as Beijing 94SJ 19, should be indicated, and the supplementary reinforcement of lintel should be indicated. When the lintel is connected with the column or constructional column, the column should be reinforced by the lintel and cast in place. Aerated concrete is not recommended as the enclosure wall, which is difficult to decorate and cannot be used in the bathroom.
(4) The layout of the canopy, balcony and overhangs and their detailed section. Note: when the canopy and balcony vertical plate are cast in place, the minimum thickness should be 80, otherwise the construction will be difficult. Vertical reinforcement should be placed in the middle of the slab. When used as double-row reinforcement, when the height is 900, the minimum thickness is 120. The balcony vertical plate is cast in place as far as possible, and cracks are easy to occur at the intersection of prefabricated baffles. When there is an inclined decorative board on the canopy and balcony, the steel bars of the board are placed on the inclined board and anchored into the wall ring beam through the lower part of the horizontal cantilever (that is, the cantilever is a double-layer steel bar). The sealing plates on both sides can be blocked with Taber plates, and the steel bars are welded with Taber plate steel wires, so it is not necessary to adopt concrete structure. When the length of cantilever plate is more than 2m, structural reinforcement shall be set under the plate, and temperature reinforcement shall be set for cantilever plate (including vertical plate) with long exposure. The length of reinforcement on the inner span of the cantilever plate should be greater than or equal to the length of the cantilever plate, especially when there is concentrated load at the end of the cantilever plate. Small vertical edges should be added at the end of the inner connecting plate to prevent dust from falling when cleaning. When the canopy of the top balcony is unorganized drainage, the canopy length should be longer than that of the lower balcony 100, and the canopy must be set on the top balcony. There should be room for the reinforcement of the cantilever plate, and the reinforcement with large diameter and large spacing should be used to give the workers a place to step on to prevent bending. The span of the inner span plate of the pick-up plate is small, and the negative bending distance may appear in the span, so the negative reinforcement of the pick-up plate support should extend to the whole span. Generally, the steel bars on the end plate of the pick-up plate are turned up, but it is difficult to construct when the diameter of the steel bar is greater than or equal to 12, so it should be reinforced separately.
(5) Stair layout. The stairwell is indicated by an X-shaped diagonal line, and the stairwell is indicated separately. Try to use slab stairs, which is convenient in design and construction and more beautiful.
(6) Elevation of the top of the slab. The thickness of most plates and the elevation of the top of the plate can be explained under the name of the drawing, and special places such as kitchen and bathroom can be marked separately in their rooms.
(7) The arrangement and numbering of beams shall be based on the number of layers, such as L- 1-XX, 1 refers to 1 layer, and XX refers to the number of beams. Column layout and numbering.
(8) The size of holes with holes (kitchen, toilet, electrical and equipment) in the plate and its additional reinforcement need not be anchored in the plate bracket, but can be anchored in La from the edge of the hole. For additional reinforcement with holes in the plate, if the plate at the hole has only positive bending distance, reinforcement can only be arranged under the plate; Otherwise, additional steel bars should be added to the upper and lower plates. The slab poured after the reinforcement is reserved is indicated by dotted line, and it is indicated that the slab is poured with expansive concrete to improve the level. Effective supporting measures should be taken before pouring. The big hole in the stair floor of residential building should not be surrounded by beams, and the internal force and reinforcement of the floor should be calculated by finite element program. Thicken the plate appropriately, and add hidden beams at the edge of the hole.
(9) Location and detailed drawing of manhole and ventilation hole on the roof.
(10) For details that cannot be clearly expressed on the plan, add a section. Based on the method of building wall section, the corresponding structural details can be drawn.
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