Reinforced concrete beams (Fig. 62) are used with spans of 6, 9, 12 and 18 m for single-slope, dual-slope and flat coatings. The beams of single-slope and flat roofs have a rectilinear upper belt, and the beams of dual-slope roofs have a broken belt with a slope of slopes of 1: 12. For spans of 6 and 9 m, beams are made of T-section with a height on a support from 390 to 790 mm, and for spans 12 and 18 m - I-beam with a height on the support from 790 to 1490 mm.
For the manufacture of beams, concrete of grades 200-500 and conventional or prestressed reinforcement are used. In the coatings of buildings with an aggressive environment, beams with bar reinforcement are recommended, which have increased resistance to corrosion.
On the upper belt of the beams, embedded elements are provided for fastening the girders or cover panels, on the lower belt and wall - embedded elements for fastening the tracks of overhead transport, and in the supporting parts - steel sheets with cutouts for fastening the beams to the columns (Fig. 62, c).
Rice. 62. Reinforced concrete roof beams
Reinforced concrete beams are easy to manufacture and install, allow the panels to be supported anywhere in the upper chord and have a small height. However, such beams are very heavy (in comparison with trusses, more concrete is consumed for their manufacture), they make it difficult to place engineering networks in the interbeam space.
The spatial system, consisting of columns, crane beams and supporting structures of the coating, is called frame one-story industrial building.
The vertical bearing elements of the reinforced concrete frame are called columns. According to their location in the building, the columns are divided into extreme and middle ones.
Columns of constant cross-section (cantilever)(Fig. 7) is used in buildings without overhead cranes and in buildings with overhead cranes.
The columns of the outer rows have a rectangular section of constant height. The middle columns, having a cross-sectional size of less than 600 mm in the plane of the transverse frame, are equipped at the top with double-sided consoles with such a protrusion so that the length of the platform for supporting the covering structure is 600 mm. With a cross-sectional size of 600 mm or more, the columns do not have consoles.
In the columns adjacent to the end walls, embedded parts must be provided on the side of the walls for fastening the half-timbered posts, which have a zero reference to the longitudinal axes.
Rice. 7. Prefabricated reinforced concrete columns for craneless spans of one-story buildings:
a - extreme columns; b, c - middle columns;
1 - embedded steel parts for fastening trusses or roof beams;
2 - the same for welding anchors fastening the wall to the columns;
3 - risks; 4 - anchor bolt
Columns are made of B15-B30 class concrete. The main working reinforcement is a rod made of hot-rolled steel of a periodic profile of class A-III.
Columns of rectangular cross-section for a building with bridge cranes, having consoles(Fig. 8, a, b), used in buildings with a span of 18 and 24 m, up to 10.8 m high, equipped with overhead cranes with a lifting capacity of 10-20 tons. The columns have a rectangular cross-section both in the upper (above the crane) and in the lower (crane) part.
Rice. 8. Precast concrete columns for crane spans:
a, b- single-branch (extreme and middle); c, d - two-branch;
1 - embedded parts for fastening beams or roof trusses; 2 - the same
for welding anchors that fasten the wall to the columns; 3 - risks;
4 - anchor bolts; 5 - embedded parts for fastening crane beams
Columns of the inner and outer rows, installed at the locations of the vertical ties, must have embedded parts for fastening the ties.
Columns are made of concrete of class B15, B25. The main working reinforcement is a rod made of hot-rolled steel of a periodic profile of the class A-III.
Two-leg columns(fig. 8, c, d) are used in buildings with a span of 18, 24, 30 m, a height of 10.8 to 18 m, equipped with overhead cranes with a lifting capacity of up to 50 tons.
For the extreme columns with a step of 6 m, a height of not more than 14.4 m and a crane lifting capacity less than or equal to 30 t, a zero reference is adopted, and in other cases - 250 mm.
The columns are designed in the lower part with two legs and connecting braces. Branches, spacers and top part all columns have a solid rectangular section.
Columns are made of concrete of class B15, B25. The main working reinforcement is a rod made of hot-rolled steel of a periodic profile of class A-Sh.
The lower parts of reinforced concrete columns inserted into the glass are not included in the nominal column height. The columns are intended for use where the top of the foundations has an elevation of -0.150. The length of the columns is selected depending on the height of the workshop and the depth of embedding into the glass of the foundation.
In buildings with truss structures, the length of the middle columns is reduced by 700 mm.
Crane and strapping beams
Reinforced concrete crane beams(Fig. 9) are used in buildings with a column pitch of 6 and 12 m, with a crane lifting capacity of up to 30 tons. The beams have T and I-sections with thickened walls on the supports. Unified dimensions of beams are taken depending on the pitch of the columns and the lifting capacity of the cranes: with a column pitch of 6 m, the beams have a length of 5950 mm, a section height of 800, 1000, 1200 mm; with a column pitch of 12 m, the length of the beams is 11 950 mm, the height is 1400, 1600, 2000 mm. They are made of concrete of class B25, B30, B40 with prestressed reinforcement.
By location in the building, run-of-the-mill crane beams and end beams are distinguished. They differ in the location of the insert plates.
In the beams, embedded elements are provided for fastening to the columns (steel sheets) and for attaching crane rails to them (tubes with a diameter of 20-25 mm through 750 mm in the length of the shelf).
The crane beams are fixed to the columns by welding of embedded elements and anchor bolts. Bolted joints are welded after final alignment. The rails are fastened to the crane girders with steel paired legs spaced 750 mm apart. Elastic spacers made of rubberized fabric with a thickness of 8-10 mm are placed under the rails and legs.
In order to avoid impacts of overhead cranes on the end walls of the building, steel stops equipped with a wooden bar are arranged at the ends of the crane runways.
Strapping reinforced concrete beams(Fig. 10) are designed to support brick and small-block walls in places where the spans heights differ, as well as to increase the strength and stability of high self-supporting walls. Usually, beams are arranged over window openings. Reinforced concrete strapping beams have a length of 5950 mm, a section height of 585 mm, a width of 200, 250, 380 mm. They are installed on steel support tables and fastened to the columns using steel strips welded to the embedded elements.
Rice. 9. Prefabricated reinforced concrete crane girders:
a - a span of 6 m; b - a span of 12 m; v - support of the crane girder
on a column (general view); d - the same, from the facade and in section;
1 - embedded parts of the column; 2 - the same crane girder; 3 - steel bar; 4 - steel plate; 5 - embedding with concrete; 6 - holes for fastening the rail
The walls above the strapping beams can be solid, with separate openings, with strip glazing.
The beams are made of B15 class concrete.
Rice. 10. Strapping beams, their support on columns:
a - rectangular beam; b - rectangular beam
sections with a shelf; c - support of the beams (bottom view) on the steel console;
1 - embedded parts; 2 - welded metal console; 3 - mounting plate
Roof and roof beams and trusses
In building coverings, load-bearing elements are beams and trusses, laid across or along the building.
By the nature of the laying, beams and trusses are: rafters, if they overlap the span, support the roof structures supported on them, and rafters, if they overlap the 12-18-meter steps of the columns of the longitudinal row and serve as a support for the rafter structures.
Reinforced concrete roof beams(fig. 11) cover spans 6, 9, 12 and 18 m.
Rice. eleven. Reinforced concrete roof beams:
a - single-slope T-section; b - single-slope I-section;
in-gable (span 6-9 m); g-gable (span 12-18 m);
d- lattice (span 12-18 m); e - with parallel belts;
1 - supporting steel sheet; 2 - embedded parts
For their manufacture, concrete of class B15-B40 is used. On the upper belt of the beams, embedded parts are provided for fastening the cover plates or purlins, on the bottom flange and the beam wall - embedded parts for fastening the tracks of the overhead crane.
The beams are attached to the columns by welding of embedded parts.
The names of the beams depend on the outline of the upper chord.
Single slope beams are used in single-span buildings. The beams have a T-section with a thickening on the supports and a wall thickness of 100 mm. For spans of 12 m, prestressed I-beams are used.
Gable beams are intended for buildings with pitched roofs. For spans of 6 and 9 m, T-section beams with a thickening on the support and a wall thickness of 100 mm are used. For 12-18 meter spans, I-beams with a vertical wall 80 mm thick and with prestressed reinforcement are intended.
Lattice beams have a rectangular cross-section with holes for pipes, electric cables, etc.
Beams Parallel belts used for buildings with a flat roof. They have an I-section with a thickening in the support nodes and a vertical wall thickness of 80 mm.
Reinforced concrete roof trusses(Fig. 12) are used in buildings with a span of 18, 24, 30, 36 m. Between the lower and upper chords of the trusses, there is a system of racks and braces. The lattice of the trusses is provided in such a way that the floor slabs with a width of 1.5 and 3 m rest on the trusses at the nodes of the struts and braces. Basically, slabs of 3 m are used, in especially loaded areas - 1.5 m.
Widely used segmented bevelless trusses with a span of 18 and 24 m, sections of the upper and lower chords are rectangular.
To reduce the slope of the coating for multi-span buildings, it is envisaged to install special racks (columns) on the upper belt of the trusses, on which the covering slabs are supported. Giving the roofing a small slope provides a better opportunity for mechanization of roofing works, which creates a greater reliability of the roof in operation. However, due to the need to increase the height of the outer walls at the same time, low-slope roofs are advisable in multi-span buildings.
Rafter farms are made of three types:
For low-slope roofs of greater heights;
For pitched roofs of lower height with the device of racks on the supports that serve as a support for the extreme decks of the covering;
With a sagging bottom belt.
In the supporting parts of the truss girder and in its middle lower node, platforms are provided for supporting the truss trusses. The trusses are made of concrete of class B25-B40. The lower belt is pre-stressed and reinforced with bundles of high-strength wire. For the reinforcement of the upper belt, braces and struts, welded frames made of hot-rolled steel of periodic profile are used.
The trusses are fastened to the columns with bolts and welding of embedded parts. The trusses are provided with embedded parts.
Rice. 12. Reinforced concrete trusses:
a, b - rafter segment diagonal;
v _ arched rafter bezel;
g_ bezel rafter with supports for the device of flat coverings;
d _ rafter with parallel belts;
e - rafter for pitched coverings;
g - rafter for flat surfaces
Snapping Columns to Building Alignment
In one-story industrial buildings with reinforced concrete and mixed frames, the columns of the outer rows have a zero reference with respect to the longitudinal alignment axes, i.e. the outer face of the column is aligned with the longitudinal alignment axis and coincides with the inner face of the wall railing. In this case, a gap of 30 mm should be provided between the inner edge of the panel and the column (Fig. 13).
Rice. 13. Binding of single-storey load-bearing structures
industrial buildings to center axes:
a- longitudinal outer walls and columns (craneless buildings);
b - longitudinal walls and columns (with cranes with a lifting capacity of up to 30 t);
v- longitudinal outer walls and columns (with cranes
lifting capacity up to 50 t); d - in the end walls;
d - in places of expansion joints (LH); e - a fragment of the building plan;
1 - walls; 2 - columns; 3 - overhead crane; 4 - bridge crane;
5 - half-timbered column; 6 - crane girder
Columns of the middle rows in reinforced concrete, steel and mixed frames have a central reference to the longitudinal alignment axis, i.e. the center axis of the middle row of columns is aligned with the cross-sectional axis of the above-crane part of the columns.
The columns of the outer rows in the steel frame in relation to the longitudinal center line have a reference of 250 mm and are aligned with the inner edge of the wall panel with a gap of 30 mm.
The end columns of the main rows of any frame in relation to the extreme transverse alignment axis have a reference of 500 mm, i.e. the column axis is 500 mm behind this transverse center line.
All half-timbered columns are installed at the ends of the spans with a step of 6 m and are intended for hanging wall panels on them and for taking wind loads. Regardless of the type of material in relation to the transverse alignment axis of the span, the half-timbered columns have a zero reference.
In reinforced concrete and mixed frames with a span of 72 m or more, and in a steel frame - 120 m or more in the middle of the spans in the transverse direction, an expansion joint is provided, which is arranged by installing a pair of columns, the axes of which lag behind the axis of the expansion joint, combined with the next step axis, 500 mm each. This creates two temperature blocks that operate independently under load. To ensure the spatial rigidity and stability of the columns in the vertical direction, vertical steel ties are provided between the columns in the middle of the temperature block between the columns (with a column pitch of 6 m - cross, with a pitch of 12 m - gantry).
Longitudinal expansion joints or the transition of heights of longitudinal spans are solved on two rows of columns, while paired alignment axes with an insert of 500, 1000, 1500 mm are provided. In a building with a steel frame, the transition of heights is carried out on one column by changing the height of its branches.
The adjoining of two mutually perpendicular spans is carried out on two columns with an insert along the outer wall and at the level of the covering. The size of the insert is determined based on the thickness of the outer walls and on the column anchors.
In a building in the presence of electric bridge cranes, the vertical axes of the crane tracks lag behind the longitudinal alignment axes of the building by 750 mm (without a passage) and by 1000 mm (with a passage), and in the presence of overhead cranes, the vertical axes of the suspension and their movement lag behind the longitudinal alignment axes by 1500 mm.
Providing spatial rigidity reinforced concrete frame
The linkage system is designed to provide the necessary spatial rigidity of the frame. It includes:
· Vertical communications;
· Horizontal ties along the upper (compressed) belt of trusses;
· Communication on lanterns.
Vertical links have:
· Between the columns in the middle of the temperature block in each row of columns: with a column pitch of 6m - cross; 12m - gantry. In buildings with craneless and overhead cranes, connections are installed only at a column height of 9.6 m. Connections are made from corners or channels and fastened to the columns using kerchiefs (Fig. 14);
· Between the supports of trusses and beams, ties are placed in the outermost cells of the temperature block in buildings with a flat covering. Without truss structures - in each row of columns, with truss structures - only in the outer rows of columns.
Horizontal ties are: slabs covering;
· At the ends of the lampposts, the stability of the rafter beams and trusses is ensured by horizontal cross braces installed at the level of the upper chord, in subsequent spans (under the lanterns) - by steel struts; with large spans and the height of the building at the level of the lower belt of the trusses, horizontal connections are arranged between the extreme pairs of trusses located at the ends of the building; in buildings with a pitch of extreme and middle columns of 12 m, horizontal trusses are provided at the ends (two in each span per temperature block). These trusses are located at the level of the lower chord of the trusses.
Precast concrete assemblies frame
Places of mates of different types of elements of the prefabricated frame are called nodes (Fig. 15). Nodes of reinforced concrete frames must meet the requirements of strength, rigidity, durability; immutability of mating elements under the action of installation and operational loads; ease of installation and termination.
Conjugation of a column with a foundation. The embedment depth of rectangular columns is 0.85 m, two-branch columns - 1.2 m. The joint is covered with concrete of a class of at least B15. Grooves on the column edges promote better adhesion of concrete in the joint cavity.
Support of the crane girder on the column projections. A steel sheet with cutouts for anchor bolts is welded to the beam supports (before its installation). On the column supports, the beam is fixed to the anchor bolts and the embedded parts are welded. The upper flange of the crane girder is fixed with steel strips welded to the embedded parts.
The connection of trusses and beams to the column. Steel sheets are welded to the supports of the truss structures. After installation and alignment, the support sheets of the rafter structures are welded to the embedded parts on the column head.
Support of truss structures on the column head. Embedded parts of abutting elements are welded with a ceiling seam.
Fastening overhead cranes to roof structures. The supporting beams of the cranes are bolted to the steel clips on the truss structures. Crossbeams redistribute the load from the overhead cranes between the truss nodes.
Conjugation of rafter and rafter elements similar to the fastening of trusses and beams to the head of the columns.
Multi-storey precast concrete frame
Multi-storey industrial buildings are erected, as a rule, with frame ones.
Depending on the type of overlap, the structural scheme of the building can be girder or non-girder.
V girder reinforced concrete frames (Fig. 16) bearing elements are foundations with foundation beams, columns, crossbars, floor panels and coverings, as well as metal ties.
Rice. 14 Ensuring the spatial rigidity of the frame:
a - placement of horizontal ties in the coating; b - reinforcement of end
walls with crown trusses; v- placement of vertical ties in buildings
with flat coverings (without rafters);
d - vertical ties in buildings with rafters;
d - vertical cross ties; e - vertical portal links;
1 - columns; 2 - roof trusses; 3 - cover plates; 4 - lantern;
5 - wind farm; 6 - horizontal cross brace (at the ends of the lamppost); 7 - steel spacers (at the level of the upper chord of the trusses); 8 - crane beams; 9 - metal tie trusses between the supports of the truss trusses; 10 - vertical cross ties (in the longitudinal row of columns); 11 - roof trusses; 12 - vertical portal links (in the longitudinal row of columns)
Rice. 15. Nodes of the reinforced concrete frame of one-story industrial buildings: a - conjugation of the column with the foundation; b - support of the crane girder
on the column; v - conjugation of beams and trusses with a column; d - support
truss structures at the head of the column; d - mounting of suspended
cranes to load-bearing roof beams; e - support of rafters
and truss beams on the column head;
g - conjugation of trusses, trusses;
1 - foundation; 2 - column; 3 - monolithic concrete; 4 - grooves;
5 - embedded part; 6 - fastening bar; 7 - bolts М20;
8 - support sheet 12 mm thick; 9 - rafter beams;
10-welded ceiling seam; 11 - rafter beam;
12 - steel clip; 13 - bearing beam of the overhead crane;
14 - roof truss
Rice. 16. Multi-storey building with beamed ceilings:
a - a cross-section of a building with slabs supported on the ledges of the beams;
b - plan; в - details of the frame; 1 - self-supporting wall; 2 - crossbar with shelves;
3 - ribbed plates; 4 - column console;
5 - reinforced concrete element for filling expansion joints
Rice. 17. Coupling of columns with each other and with girders:
a - the structure of the joint of the columns; b - general view of the interface between the column and the girder;
1 - abutting column heads; 2 - centering gasket;
3 - straightening plate; 4 - the reinforcement of the column is working;
5 - the same transverse; 6 - butt rods;
7 - caulking and embedding with concrete of class B25; 8 - crossbar;
9 - floor slab (tie); 10 - column inserts
crossbars and slabs; 11 - welding of reinforcement, released from the column and girders;
12 - plate for plate welding
The foundations are arranged in columnar glass type.
Columns with a section of 400 x 400, 400 x 600 mm cantilever type with a height of one floor (for buildings with a floor height of 6 m and for the upper floors of three- and five-story buildings), two floors (for the two lower and also for the upper floors of four-story buildings ) and three floors (for buildings with a floor height of 3.6 m). The outer columns for supporting the girders have consoles on one side, while the middle columns have consoles on both sides. Columns are made of concrete of class B15-B40.
Crossbars are laid on the console of the columns in the transverse direction. They are made of concrete of class B25, B30. The crossbars of the first type (with shelves for supporting the slabs) cover spans of 6 and 9 m. The crossbars of the second type have a rectangular cross-section, they are used in ceilings when installing sagging equipment.
Floor and roof slabs are manufactured with longitudinal and transverse ribs from concrete of class B15-B35. In terms of width, they are divided into main and additional ones, laid at the outer longitudinal walls. The main slabs laid on the top of the girders have cutouts at the ends (for the passage of the columns). For floor loads of up to 125 kN / m 2, flat hollow slabs are used, and sanitary panels are laid along the middle rows of columns.
Connections between the columns installed floor by floor in the middle of the temperature block along the longitudinal rows of columns. They are made of steel corners in the form of portals or triangles of the same design as in one-story buildings.
Binding columns of the outer rows and outer walls to the longitudinal alignment axes is zero, or the alignment axis of the building runs along the center of the column. The binding of the columns of the end walls is assumed to be 500 mm, and in buildings with a column grid of 6x6 m - axial. The columns of the middle rows are located at the intersection of the longitudinal and transverse axes. Frame nodes(Fig. 17) - these are support connections of the same type or different types of prefabricated elements that provide the spatial rigidity of structural rods. The main nodes include:
coupling of crossbars with columns is achieved by welding the embedded parts of the girders and consoles of the columns, as well as welding the outlets of the upper reinforcement of the girders with the rods passed through the body of the column. The gaps between the columns and the ends of the girders are filled with concrete;
column joints multi-storey buildings for ease of installation are provided at a height of 0.6 m from the floor level. The ends of the columns are equipped with steel heads. The joint is carried out by welding butt rods to metal heads, followed by monolithing;
floor slab joints. The laid slabs are connected by welding of embedded parts with girders, with columns and with each other. The cavities of the joints between the ribs are embedded in concrete. Bezelless reinforced concrete frame with a grid of 6x6m columns in the form of a multi-tiered and multi-span frame with rigid nodes and floor loads from 5 to 30 kN / m2 (Fig. 18).
The main elements of the frame: columns, capitals, intercolumnar and spans - are made of concrete of class B25-B40.
Columns with a height of one floor are installed on a 6x6m grid. In the upper part of the column there is a broadening (head) for supporting the capitals, which looks like an overturned truncated pyramid with a through cavity for mating with the ends of the columns.
Rice. eighteen. Multi-storey building with non-girder ceilings:
a - cross section; b - plan; 1 - self-supporting wall;
2 - column capital; 3 - intercolumnar slabs; 4 - the same spans
Fig. 19... Prefabricated non-girder floor:
a - plan and sections; b - general view;
1 - column head; 2 - capital; 3 - intercolumnar plate;
4 - the same span; 5 - monolithic concrete; 6 - monolithic reinforced concrete;
7 - shelf for supporting the flight plate; 8 - column
The capital is put on the head and secured by welding steel embedded parts. Hollow-core intercolumnar slabs are laid on the capitals in two mutually perpendicular directions and welded at the ends to the embedded parts of the capitals. After installing the column of the next floor, the joint is poured with concrete. Then, steel reinforcement is laid in the zone between the ends of the intercolumnar plates, welding it to the embedded parts. After concreting, the slabs work as continuous structures.
The overlap sections, bounded by intercolumnar slabs, are filled with square-shaped span slabs, resting them along the contour on the quarters provided in the lateral faces of the intercolumnar slabs.
The main nodes of a non-girder frame include (Fig. 19): column joints, located 1 m above the floor, the same structure as in the beam frame; the junction of the capital with the column. The capital is supported on the four-sided console of the column, welding embedded parts from below, and reinforcing plates on top. The gap between the column and the capital is monolithized with concrete of class B25; floor slab joints. The intercolumnar slabs are supported by the outlets of the reinforcement on the embedded parts, embedding the joint with concrete. The spans are supported by the outlets of the reinforcement on the embedded parts of the intercolumnar panels. After welding, the wedge-shaped grooves of the joints are monolithic.
Preface to the second edition 3
Introduction 4
Chapter 1. Space planning solutions AND
1.1. Building types. Basic requirements for building solutions. AND
1.2. Column grid, rafter spacing 13
1.3. Unification of volumetric planning solutions and building layouts 15
Chapter 2. Structural schemes of buildings 20
2.1. Building framework schemes 20
2.2. Structural schemes of coatings 21
2.3. Rigidity and stability of the building frame and structures
coverings, solution of ties 34
Chapter 3. Basic provisions for the unification of structures. ... 46
3.1. Modular system. Nominal and structural dimensions of elements 46
- 3.2. Snapping Alignment Lines and Structures 49
3.3. Unification of loads 53
3.4. Unification of mates of structural elements 56
3.5. Unification of elements 58
Chapter 4. The main provisions of the design of precast concrete structures 60
4.1. Design code 60
4.2. Reinforcing steels 61
4.3. Purpose of reinforcing steel for structures operated at different design temperatures 66
4.4 Reinforcement of precast concrete structures. Unification of reinforcement products. 69
4.5. Design issues of prestressed reinforced concrete structures 74
4.6. Embedded parts: 78
4.7. Requirements for structures of buildings with aggressive environments 82
4.8. Requirements for the structures of buildings erected in seismic areas 85
4.9. Requirements for transportation and storage of structures 86
Chapter 5. Foundations and foundation beams 88
5.1. Zero cycle 88
5.2. Types of foundations and their area of application 90
5.3. Issues of designing prefabricated foundations. ... 92
5.4. Foundation beams 95
5.5. Strapping beams and lintels 99
Chapter 6. Columns 101
6.1. Column types and their field of application 101
380
6.2. Features of static analysis of columns
6.3. The main questions of the constructive solution of the columns
64. Typical rectangular columns for buildings without cranes and with cranes
6 5. Typical two-branch columns for buildings with overhead cranes
6 6. Typical two-branch columns for buildings with aisles at the level of crane girders
Teague
6 7. Typical two-branch columns for buildings without cranes and overhead transport
6.8. Typical columns of end and longitudinal half-timbered houses
6.9. Typical columns for seismically erected buildings:
districts
6.10. Typical columns for buildings with increased temperature blocks
611. Typical columns for buildings with an aggressive environment
6 12. Work on the further improvement of the columns
Head (t ^ Roof beams
7 1. "Scope of beams
7 2. * Basic provisions for the designation of overall dimensions and static calculation of beams
7.3.b Basic provisions for calculating beams in terms of strength, stiffness, formation and opening of cracks
7 4y Selection of the outline and design of roof beams
7 5. Beams with tension-free reinforcement
7.6. Beams with beam and bar reinforcement, tension
on concrete
7.7. Beams with rod and wire reinforcement, tensioned on stops (according to the drawings of the first development)
7.8. Beams with rod reinforcement, tensioned by electrothermal method (according to the drawings of the first developments)
7.9. Typical bar, wire and strand beams for pitched roof buildings
7. | 0. Typical bar, wire and strand beams for flat roof buildings
7.11. Typical beams for buildings with a highly aggressive environment
12. New developments of roof trusses
Head of roof trusses
8.1. Scope and types of roof trusses. ... ...
8 2. Features of the collection of loads when calculating trusses ....
8 3. Basic provisions of static analysis of trusses
8 4. Basic provisions for strength analysis of truss elements
8 5. Issues of calculating trusses for the formation or opening of cracks and deformations
8.6. The main conditions for the appointment of the overall dimensions of the trusses
sizes of sections and their elements
8 7. Construction of trusses and their elements
88. Features of designing truss joints
89. Trusses with beam and rod reinforcement, tensioned
on concrete
8.10. Feetsy with wire and rod reinforcement, tensioned on stops
8.11 Linear element trusses
8.12. Electro-tensioned trusses with rod reinforcement 226-
8.13. Typical Parallel Roof Trusses
buildings with a flat roof 228
8.14. Typical segment trusses for roofing buildings with pitched roofs 232
8.15. Bevelless prestressed trusses and arches 237
8.16. Application of typical trusses in seismic areas. 245
CHAPTER (§1 Reinforcement structures 246
9.1. Scope and types of rafter structures 246
9.2. Basic provisions for the static analysis of sub-rafter structures. ". 248
9.3. Appointment of the overall dimensions of the rafter structures and their cross-sections 252
9.4. Features of the design of rafter beams and trusses 253
9.5. Truss structures with beam reinforcement. ... 260
9.6. The first truss structures with reinforcement tension on stops 262
9.7. Typical truss beams with tensioned reinforcement
on stops 265
9.8 Typical roof trusses for pitched buildings
roofing 267
9.9. Typical roof trusses for flat buildings
roofing 271
9.10. Selection of typical subrafter structures in the design of buildings 273
9.11. Experimental development of roof trusses. ... 274
Chapter (a Crane beams 276
10.1. Applications 276
10.2. Design issues of crane beams 277
10.3. Experience in the use of crane girders from the first developments 279 ■
104. Typical crane girders 280 4
10.5. Variants of crane girders based on standard solutions 283 1
10.6. Fastening of crane beams and crane rails. ... ... 284
Chapter "Coating boards 287
11.1. Types of slabs ... 287
11.2. Information on the calculation and design of plates 288
11.3. Typical reinforced concrete slabs 6 m long 290 ^
11.4. Typical single-layer 6 m long honeycomb slabs
concrete 296
11.5. Typical 6 x ribbed slabs with aerated concrete shelf 297
11.6. Typical 6 m slabs made of lightweight concrete 298
11.7. Typical reinforced concrete slabs 12 m long 300
11.8. Typical Perforated Slabs for Easy Drop Roofs and Other Special Applications 307
11.9. Complex plates 308
11.10. Experimental designs of roof slabs .... 31?
Chapter 12. Wall Panels 315
12.1. The use of panels in the construction of one-story industrial buildings 315
12.2. Types of panels and their field of application 317
12.3. Constructive solutions for panel walls 318
12.4. Panels 6 l long for unheated buildings ... 321
12.5. Single-layer 6 m long aerated concrete panels for
heated buildings 324
12.6. Single-layer 6 m long lightweight concrete panels for
heated buildings 326
12.7. 3-layer panels 6 m long for heated buildings 327
12.8. Panels 12 m long for unheated buildings. ... ... 329
12.9. Panels 12 m long for heated buildings .... 330
12.10. Panel walls of buildings designed for use
under special conditions 333
12.11. Panels for walls, gables, cornices, parapets
and partitions of buildings 336
12.12. Faced panels 337
Chapter 13. Control of strength, stiffness, crack resistance of const
workmanship and workmanship 339
13.1. Quality control system for the production of precast concrete structures 339
13.2. Basic provisions for the control of strength, stiffness and
crack resistance of structures 341
13.3. Test loads and evaluation of test results 344
13.4. Methods for testing structures at enterprises. ... ... 346
13.5. Registration of test results of structures ... 353
12..6. Acceptance of prefabricated elements for installation. ... 355
Chapter 14 Issues of economics of application of precast concrete
designs 356
14.1. Wholesale prices for precast concrete products. ... ... 356
14.2. Cost reduction issues for precast concrete 360
14 3. District unit rates for construction works on
erection of precast concrete structures in buildings 362
14.4. Indicators for comparing the estimated cost and labor intensity of structures in 365
14 5. The concept of the impact of technical and economic indicators
load-bearing and enclosing structures on estimated cost industrial buildings 367
Index of series of typical working drawings 372
Roof beams can have a span of 12 and 18 m, and in some structures - a span of 24 m. The outline of the upper belt with a gable roof can be trapezoidal with a constant slope, broken or curved, Figure 4.8. The beams of a shed cover are made with parallel belts or a broken bottom belt, a flat cover - with parallel belts. The pitch of the roof beams is 6 or 12 m.
Figure 4.8 - Structural diagrams of roof beams:
a) - gable with a rectilinear outline of the belt; b) - the same broken; c) - the same curvilinear; d) - single-slope with parallel belts; e) - the same with a broken lower belt; f) - flat
The most economical cross-section of roof beams is an I-beam with a wall, the thickness of which (60 ... 100 mm) is set mainly from the conditions of the convenience of placing the reinforcing cages, ensuring strength and crack resistance. At the supports, the wall thickness gradually increases and widening is arranged in the form of a vertical stiffener. The walls of the beams in the middle part of the span, where the lateral forces are insignificant, can have round or polygonal holes, which somewhat reduces the consumption of concrete, creates technological convenience for through wiring and various communications.
The height of the section of the beams in the middle of the span is taken as 1/10 ... 1/15 l... The height of the section of the gable trapezoidal beam in the middle of the span is determined by the slope of the upper chord (1:12) and the typical size of the height of the section on the support (800 mm or 900 mm). In beams with a broken outline of the upper chord, due to the slightly greater slope of the upper chord in the extreme quarter of the span, a large section height in the span is achieved while maintaining the typical size - the section height on the support. Beams with a curved top chord approach the outline of the bending moment diagram and are theoretically somewhat more advantageous in terms of material consumption; however, the complicated shape increases the cost of their manufacture.
The width of the upper compressed flange of the beam to ensure stability during transportation and installation is 1/50 ... 1/60 l... The width of the bottom shelf for convenient placement of longitudinal stretched reinforcement is 250 ... 300 mm.
Gable beams are made of concrete of class B25 ... B40 and are reinforced with prestressing wire, rod and rope fittings, Figure 4.9. When reinforcing with high-strength wire, it is placed in groups of 2 pieces. In an upright position, which makes it convenient for concreting beams in a vertical position. The wall of the beam is reinforced with welded frames, the longitudinal rods of which are assembly, and the transverse ones are calculated, ensuring the strength of the beam along inclined sections. The support sections of the beams to prevent the formation of longitudinal cracks when releasing the tension of the reinforcement (or to limit the width of their opening) are reinforced with additional transverse rods, which are welded to steel embedded parts. The crack resistance of the support section of the beam can be increased by creating a biaxial prestressing (by tension also of the transverse bars).
To limit the width of the opening of cracks arising in the upper zone when releasing the tension of the reinforcement, it is advisable to reinforce gable beams of I-section with structural prestressing reinforcement placed at the level of the top of the section on the support, Figure 4.10. This reduces the eccentricity of the compression force and the preliminary tensile stresses in the concrete in the upper zone.
Gable beams of rectangular section with often located holes are conventionally called lattice beams, Figure 4.11. Typical lattice beams, depending on the value of the design load, have a gradation of the width of the rectangular section of 200, 240 and 280 mm. For fastening the roof slabs, steel parts are laid in the upper chord of all types of beams.
Figure 4.9 - Gable roof girder with an I-section with a span of 18 m: 1 - prestressing reinforcement; 2 - welded frames; 3 - support sheet δ = 10 mm; 4 - anchors of the support sheet; 5 - clamps Ø5 mm every 50; 6 - walls Ø5 mm
Figure 4.10 - Diagram of the arrangement of the prestressing reinforcement of a gable girder:
1 - bottom reinforcement; 2 - upper reinforcement
Figure 4.11 - A gable lattice girder of a roofing of rectangular cross-section with a span of 18 m
Discipline "Structures made of wood and plastic"
5.1 Select the cross-section of a single-span hingedly supported timber beam, pine grade 2. The beam has a span l= 4 m and accommodates a uniformly distributed load q= 2.2 kN / m.
Bending moment: M = 2.2 · 4 2/8 = 4.4 kNm. Required moment of resistance: W tr = M / Ru = 4.4 · 100 / 1.3 = 338.5 cm 3
where R u = 13 MPa = 1.3 kN / cm 2
We set the section width at = 10 cm; find
| h tr = | 6Wtt | = | 6 × 338.5 | = 14.25 cm | |||||
| v | |||||||||
We accept a beam with a cross section of h = 10 15, F = 150 cm 2.
W = bh 2/6 = 10 15 2/6 = 375 cm 4.
I = bh 3/12 = 10 15 3/12 = 2812.5 cm 3.
5.2 Determine the load-bearing capacity of a centrally compressed bar, one end of which is clamped in the foundation, the other is free. Fir grade II material. Operating conditions - B1. Cross-section of the rod - 100x150 mm, geometric length l= 3 m
The bearing capacity of the centrally compressed bar, taking into account its stability, is determined by the formula:
N = φА calc m п m in R c.
where m p = 0.8;
R c = 13MPa (for II grade fir).
The calculated cross-sectional area is found by the formula:
A calc. = A time. (since there are no weakenings, according to SP 64.13330.2011).
A calc. = 10. 15 = 150 cm 2
To determine the coefficient φ, we calculate λ the flexibility of the element
The calculation is carried out for greater flexibility λ x = 103.8. For flexibility λ> 70, we determine the φ coefficient using the formula.
Lesson 53-54 (9-10)
1. The foundations take the loads from the above-ground part, transfer them to the foundation.
2. The work of foundations - in changing conditions from loads, increased requirements for their quality.
3. Requirements for materials for foundations :
a) mechanical strength
b) high frost resistance
c) durability
d) resistance to aggressive groundwater.
4. Classification of foundations of industrial buildings :
A) by constructive solution: tape, columnar, pile.
B) by construction technology: monolithic and prefabricated
C) by deepening - shallow and deep.
Columnar foundations for industrial frame buildings (p. 180)
1. Monolithic under a reinforced concrete column: sub-column + glass + plate with steps. (rice)
2. The bowl has a widening on top for ease of installation and centering of the column.
3. The depth of the glass is 50-150 mm more than the column inserted into the glass.
4. The bottom of the column is fixed with sand or concrete, the gaps between the glass and the column are filled with concrete or mortar.
5. Two-branch columns - in a common glass or two glasses for each branch (b).
6. In expansion and settlement joints, each column needs its own glass.
7. If the seam is sedimentary, arrange for each column - its own foundation.
8. Preparation for the foundation - concrete of class B5 with a thickness of 100 mm.
9. The foundation slabs and the sub-column are reinforced.
10. Concrete for the foundation - class B 12.5, B15.
11. Working fittings - steel of classes A-II and A-111.
12. The sub-column is supported on one, two or three rows of foundation blocks.
13. The bottom row of blocks - on a sand preparation at a distance of 600 mm from each other.
14. Precast foundation slabs are placed on the leveling layer of sand.
Foundations for metal columns (182)
1. Columnar with sub-column continuous cross-sections
2. The top of the sub-column is positioned at the -0.600 or -0.200 mark.
3. A support base is arranged near the column - a shoe. A steel sheet is laid under the column to evenly transfer the load to the concrete area of the foundation.
4. The base is deepened below the level of c.h. and concrete).
7. The bases are fixed to the foundations with anchor bolts embedded in the foundations during their manufacture.
8. The bolts are threaded through the base plate and other base members.
9. The height of the sub-column is not less than 700 mm
10. The walls of frame buildings are supported on the foundation beams between the sub-columns.
11. Under the gate to enter the workshop, foundation beams are not laid.
12. Wall sections within this column spacing rest on a monolithic foundation.
RC foundation beams (183)
1. Have a trapezoidal or tee section.
2. Their dimensions depend on the pitch of the columns.
3. Beams at the expansion joint and end walls are shortened by 500 mm.
4. The top of the foundation beams is 30 mm below the floor level.
5. Install the beams on a 20 mm thick cement-sand mortar grout.
6. The gaps between the ends of the beams and the columns are filled with the same solution.
7. On the foundation beams - waterproofing of walls - 1-2 layers of roll material.
8. In order to avoid deformation of the beams from heaving of soils from below and from the sides of the beams, backfill from slag, sand or brick crushed stone.
9. Beams are made of concrete of class B15-B30.
Pile foundations under the columns of industrial buildings
1. Driven or rammed piles + grillage from above + reinforced concrete shoe with a glass for columns.
2. Pile foundations are suitable when weak pounds occur at the surface of the earth and in the presence of pound waters.
Lesson 55-57 (11-13)
Topic 3.5.3. Reinforced concrete structures of industrial buildings
1. Frame of a 1-storey industrial building - columns + crane beams + coverings.
2. Columns of the frame: extreme and middle.
3. Types of columns
A) constant section (cantilever): 185
* for buildings with overhead cranes
* extreme - rectangular of constant cross-section, middle - with a console
B) rectangular section with consoles- fig. 186, a, b
* for a building with a span of 18 and 24 m, a height of up to 10.8 m with overhead cranes gr. 10-20 t.
* the outer columns are single-cantilevered, the middle ones are double-cantilevered.
V) two-branch columns(186, c, d)
for buildings with a span of 18, 24, 30 m, a height of 10.8 -18 m, with bridge cranes gr. up to 50 t.
G) prefabricated reinforced concrete columns for craneless spans of one-story buildings.