Characteristics of Structural Design Solutions for Public Building Project Documentation
We have developed the complete design documentation and working drawings for the reconstruction of a public building.
STRUCTURAL SOLUTIONS. Development of Reconstruction Project Documentation.
General Information on Public Building Project Documentation
This project provides for the reconstruction of the facility: "Multi-story non-residential public buildings".
Physical and Geographical Conditions
The surface is currently graded with fill soils and built up. Modern physical and geological processes capable of negatively influencing design decisions were not observed at the work site.
Climate
The work area falls within the zone of a temperate-continental climate with the following average annual indicators: temperature - plus 6.2° C, precipitation - 500 to 650 mm (586 mm), number of days with an average daily temperature above 0° C - 210 to 214. The greatest amount of precipitation occurs in the spring-summer period. The average January temperature is minus 14.5° C, July - plus 26.1° C (with maximums of 36.0° to 38.0° C). Winter lasts 4.5 months. The average annual relative air humidity is 79%.
The estimated standard depth of seasonal soil freezing was calculated and complies with relevant building codes. The seismicity of the territory is less than 6 points.
Engineering and Geological Conditions of the Site
Geological Structure
The geological structure of the site down to a depth of 23 m involves 4 stratigraphic-genetic complexes:
- modern soil-vegetation layer;
- modern technogenic (fill) layer;
- Upper Quaternary alluvial deposits;
- Upper Jurassic deposits.
The modern soil-vegetation layer, encountered by boreholes, is represented by light loam with an admixture of humus and inclusion of roots, with a thickness of 0.2 m. Modern technogenic formations are represented by compacted fill soil - fine and medium-coarse sand, with inclusions of up to 10-15% of grit, crushed stone, construction debris, sometimes mixed with loam, with a thickness of 2.3 - 4.3 m.
Upper Quaternary alluvial deposits are widespread, lying beneath the fill formations and represented by medium-coarse sand and fine sand, as well as gray, stiff loam.
Upper Jurassic deposits lie at a depth of 13.5-19.6 m and are represented by dark gray to black, hard, silty, micaceous clay.
Hydrogeological Conditions
The hydrogeological conditions of the site are characterized by the presence of a supra-Jurassic aquifer, encountered at a depth of 4.2-5.8 m and associated with sands of the Upper Quaternary alluvial deposits. The aquifer is unconfined; the lower aquitard is Upper Jurassic clays.
Based on field and laboratory work, soil layers were identified, and their physical, deformation, and strength characteristics, as well as their corrosive and aggressive properties, were determined. Laboratory determinations were carried out using automated compression and shear testing equipment. Static penetration testing was conducted. Field plate load tests were performed to determine the deformation properties of soils.
Soil Properties
Based on the analysis of spatial variability of soil property indicators, 5 engineering-geological elements were identified, constituting the design model of the foundation.
Measures in Connection with Construction in Special Conditions
Where possible, the use of technogenic soils as a foundation base without preliminary preparation should be excluded, as they can cause significant and uneven settlements. Based on the engineering-geological conditions of the site, it is recommended to provide protection for underground structures prone to corrosion from the aggressive effects of soils.
Structural Solutions and Brief Characteristics of Building Structures
The building consists of blocks differing from each other in structural schemes and number of stories.
Block with a basement story, L-shaped in plan, with overall dimensions accordingly, height to the top of the parapet ~ 30.0 m. On the second floor, a transitional gallery is provided for connection between the adjacent building.
Block No. 1 has a frameless structural design scheme with load-bearing longitudinal and transverse brick walls with a thickness of 380-770 mm. Foundations under load-bearing walls are strip foundations made of rubble stone. Interfloor ceilings of the basement, second, fourth, fifth floors, as well as the roof are monolithic reinforced concrete; for spans more than 3 m - on reinforced concrete and metal beams. Interfloor ceilings of the first and third floors are wooden; for spans less than 3 meters, they are monolithic reinforced concrete.
Stair flights are made of precast reinforced concrete steps on metal I-beam stringers, plastered over mesh. Stair landings are made of monolithic reinforced concrete on metal I-beams, plastered over mesh. The roof of the block is flat, rolled. Drainage from the roof is external, organized.
Reconstruction of a Public Building. Fire Safety Measures
In connection with fire safety requirements, the project provides for:
- replacement of wooden floors;
- reconstruction of stair flights and landings.
Description and justification of structural solutions for buildings and structures, including their spatial schemes adopted when performing calculations of building structures.
The structural solutions section is based on the developed architectural drawings and solutions of engineering sections, taking into account the location of the building on the master plan. The level of the finished floor of the first floor is taken as mark 0.000.
The building is U-shaped in plan.
The building's level of responsibility is normal.
The reconstruction involves the installation of reinforced concrete floor slabs, as well as the creation of an attic space.
The structural system is frame. The structural scheme features monolithic reinforced concrete floor discs resting on brick stiffening diaphragms (510 mm).
Spatial Rigidity and Geometric Stability
of the building is ensured by rigid discs of floors and the roof, brick walls installed on all floors, and stairwell walls.
The frame of the building was calculated using the finite element method, taking into account an elastic base. The calculation considered permanent and temporary loads on floors, snow load, two wind exposures considering pulsation components, and temperature effects.
The snow load is assumed to be 180 kg/m2.
The design model includes structures with the following characteristics:
- walls - brick, thickness 510 and 380 mm;
- floor slabs - monolithic, thickness 220 mm;
- hot-rolled metal sections (for attic construction);
- stairs - monolithic reinforced concrete.
All load-bearing structures are made of concrete class B25. Main reinforcement - class A-III (A400), transverse reinforcement - class A-I (A240).
Replacement of wooden floors at the floor levels is provided. The floors are made of monolithic reinforced concrete class B25 on metal I-beams using permanent formwork made of profiled sheet. Reinforcement with class AIII rebar.
Description and justification of technical solutions ensuring the necessary strength, stability, spatial stability of the building as a whole, as well as its individual structural elements, joints, and details.
Walls - load-bearing, thickness 380 mm (510 mm) made of ceramic brick on cement-sand mortar M75; tied with reinforcement mesh every three rows of brickwork.
Stairs and stair landings - monolithic reinforced concrete thickness t=160 (220) mm made of concrete class B25, longitudinal and transverse reinforcement class A-III (A400). Floor and roof slabs of the building - monolithic reinforced concrete thickness t=220 mm made of concrete class B25, longitudinal and transverse reinforcement class A-III (A400).
Reinforcement of reinforced concrete structures is provided with rebar class A400, A240 as per calculation and not less than the minimum reinforcement percentage of 0.15%. The concrete grade for water resistance for walls below ground level is W6, for other structures not less than W4.
The concrete grade for frost resistance for all structures must be at least F50. Lap splices for longitudinal reinforcement should be provided without welding.
All load-bearing frame structures are assigned fire hazard class K0 and ensure the building's constructive fire hazard class C0. The fire resistance rating of structures is as follows:
- frame walls - fire resistance rating REI 90;
- floors - fire resistance rating REI 45;
- stair flights - fire resistance rating R 60.
Concrete cover for load-bearing structures is adopted depending on the fire resistance rating. Concreting of all frame elements must be carried out in accordance with requirements and the work execution project developed by the contractor.
The project was developed for construction at positive ambient temperatures. When performing monolithic concrete and reinforced concrete structures, measures ensuring the necessary temperature and humidity for normal concrete curing must be applied.
All materials and products delivered to the construction site must be accompanied by documentation confirming their quality and compliance with the project.
To ensure the strength, stability, and spatial stability of the building, construction work must be carried out in accordance with the construction organization project and work execution project.
Description of engineering solutions and structures ensuring protection of the territory, individual buildings, and personnel from dangerous natural and technogenic processes. The building was designed for areas with seismicity of 6 points. The fire resistance of load-bearing and enclosing structures corresponds to the degree of fire resistance adopted in the project.
The following main dangerous natural processes, activated by geophysical influences, may occur at the construction site:
- extreme atmospheric precipitation;
- hurricanes.
The project includes engineering solutions aimed at minimizing the negative consequences of dangerous natural phenomena.
Stormwater precipitation: Planning solutions provide for the diversion of stormwater runoff to driveways and the terrain.
Anti-Corrosion Protection
All metal structures, details, and welded connections are protected by anti-corrosion coatings. Protection against corrosion is carried out in accordance with building codes. The composition and methods of applying anti-corrosion coatings are assigned according to requirements. All wooden elements in contact with wall structures and reinforced concrete products are laid on a layer of roofing felt or hydro-insulation and thoroughly antiseptized.
All reinforced concrete structures in contact with the ground are coated with 2 layers of hot bitumen over a primer. To increase water resistance and prevent capillary penetration of moisture into rooms located below the groundwater level, the walls and floors of the premises are plastered over a reinforcement mesh with mortar M100 with the addition of a waterproofing admixture.
Requirements for ensuring control of structures, materials, and products used in construction. In accordance with regulations, the use of new materials, products, and structures must have a technical certificate confirming their suitability for use in construction.
All construction materials must undergo radiation control and meet the requirements of radiation safety standards. The results of radiation control must be transferred to the customer and the author's supervision representative before the start of work.