Abstract
Contents
- Introduction
- 1. Theme urgency
- 2. Goal and tasks of the research
- 3. Overview the results of research
- 3.1. Types of deformation of grounds and buildings
- 3.2. Methods for measuring the deformation of buildings and grounds
- 3.3. The study of the operating conditions of buildings DonNTU
- 3.3.1 Brief description of the construction of educational buildings N1 and N2
- 3.3.2 General information about the building structure of educational building N3
- Conclusion
- References
Introduction
Normal operation of buildings and structures significantly complicate the structural damage, and sometimes this kind of damage lead to a crash. Therefore, prevention of damage is one of the most important tasks in ensuring the normal operation of such facilities.
Engineering solutions for the prevention of damage possible on the basis of diagnosis of the cause. Geodetic measurements, which consists in determining the change of position of structures in space, allow to estimate the size of damage, and long-term monitoring of damageable objects can also assess the causes of such injuries.
To hold and accumulate geodetic observations selected academic buildings N1, N2, N3 and manufacturing buildings of Donetsk National Technical University (DonNTU) that are in difficult conditions. Observations of the deformation of the structural damage to buildings and educational buildings are held by students of the 3rd year, which studying to on specialty Engineering Surveying
in Engineering geodesy
during training practice.
The generalization of the results of observations of deformation of the grounds and buildings of educational buildings DonNTU will give an idea of the degree of deformation, as well as to determine the intensity of these strains for further normal operation of buildings and structures.
1. Theme urgency
The complexity of the whole operation of urban development and lands of DonNTU caused by holding the territory mining. Conducting mining works leads to the earth's surface differential subsidence and deformation, which disrupt base objects of the earth surface and cause damage in undermining objects.
Also, in the city there are active geodynamic zone that also cause disturbances in the normal operation of buildings. Some of the harmful effects on buildings and structures should also include the proximity of the seismic zones, which causes fluctuations in the structures, which also leads to damage. In addition, the city streets is heavy-duty trucks, which together with continuous seismic vibrations cause tremors damaged part-time job structures, which leads to activation of previously incurred damage.
For the reasons given, the topic on the basis of observations of deformations, allowing to determine the intensity of the changes in the deformation is quite urgent.
2. Goal and tasks of the research
Purpose of master's work: To summarize the data and identify the strain variation grounds and buildings, which interferes with the normal operation of academic buildings DonNTU.
Purpose intermediate stage of theme is the accumulation of the results of geodetic observations for further analysis using geodetic methods for diagnosis of structural damage and deformation of the buildings in the complex conditions of their operation.
Research objectives: Identify changes deformations grounds and buildings in order to establish the rate of damage to determine knots in the emergence of dangerous damage to further enhance safety and the normal operation of buildings DonNTU.
The idea of work: To clarify with observations the relationship and identify the growth of the earth surface deformation (bases of buildings and structures) and the nature of the damage hull DonNTU.
Object and subject of study: To identify the growth strain DonNTU buildings that are in difficult conditions. Subject of research are cracks in load-bearing structures and monitor the dynamics of disclosure and comparison of their changes with valid values.
Possible results to be expected in the performance of their novelty and significance: Display the state of deformation of buildings and grounds DonNTU academic buildings that will show them the security and normal exploitation. These results are very important for the normal operation of the further building of DonNTU.
3. Overview the results of research
3.1. Types of deformation of grounds and buildings
Deformation of the grounds and buildings can be divided into the following types:
1. Draft – the offset caused by compaction (compression) of the soil under load, which is not accompanied by a strong change in the addition of soil or reducing the vertical size of the building (or part thereof). Drafts can be divided into three types:
absolute draft grounds or buildings: determined separately for each base;
average draft grounds or buildings: determined by the absolute drafts at least accordings to three separate foundations or three sites common ground building or structure;
additional draft grounds or buildings: this draft is the sum of all the negative factors affecting the foundation or building (soil moisture grounds rain and melt water, otmostok fault, availability under the foundation (-s) of old, carelessly buried mines, the freezing of the base, the dynamic effect of shock or vibrating equipment on foundations and bases, etc.).
2. Drawdown – the disastrous nature of the deformation caused by the collapse of the overlapping cover or karst rocks.
3. Tilt – the position at which the plane of symmetry of the building from vertical, forming a slope (pic. 1) is characteristic of the roll rigid structures;
Picture 1 – Tilt of the building
(animation 30 frames, infinite cycles quantity repetition, 255 KB)
4. Skewness – the difference between the two sediment adjacent foundations, referred to the distance between them; bias characteristic mainly for the building frame system (pic. 2);
Picture 2 – Skewness of the building
5. Shift (sliding) – horizontal displacement as a consequence of the base seismic, vibration and other stresses.
6. Relative deflection (relative inflection) – the ratio of the deflection to the length of the building, which is bent (pic. 3).
Picture 3 – Relative deflection (а) relative inflection (б) of the building
(animation 21 frame, infinite cycles quantity repetition, 98 KB)
7. Torsion – rotation of the building foundation on its axis (pic. 4).
Picture 4 – Torsion of the building
8. Horizontal deformation of the building – change the horizontal length of the building or structure under the influence of the horizontal deformation of the base.
9. The curvature of the earth's surface – a phenomenon that expresses the change of landforms, opredeleyuscheesya by changing its slope.
10. The slope of the building or structure – changing the shape of the building or structure on the phase angle vsledstie appearance in cross-section shear stresses [11]
.Based on the analysis and synthesis of long-term records for the deformation of the building and can be characteristic of the current state of the grounds and buildings, as well as the intensity and magnitude of these strains in time for their possible implications. Building codes, limits the amount of strain that failure to ensure the normal operation of buildings and structures. Exceeding the limits of deformations can crash or complete destruction of the building.
During the measurements, and the deformation of the buildings should be identified (individually or together), the following values:
vertical movements;
horizontal movements;
tilts of the building.
Observations of the deformation of the building and should be made in the following sequence:
development of a measurement program;
the choice of design, location and installation of geodetic marks altitude and planning framework;
implementation of the planned altitude and bindings installed geodetic marks;
installation of expansion (sedimentary) marks on the grounds and buildings;
instrumental measurements of the vertical and horizontal movements and rolls;
processing and analysis of observations [14].
3.2. Methods for measuring the deformation of buildings and grounds
Methods for measuring the deformation can be divided into three types:
1. Methods of measuring the vertical displacement . Vertical movement of the foundation base should be measured by one of the following methods or a combination thereof: geometric, trigonometric or hydrostatic leveling, photogrammetry.
Individual methods of measuring vertical displacement should be taken depending on the classes of accuracy, suitable for this method:
spirit leveling – I-IV class;
trigonometric leveling – II-IV class;
hydrostatic leveling – I-IV class;
photogrammetry – II-IV class.
The method of leveling work frames in accordance with the Instructions ...
[8, 9].
Spirit leveling should be used as the primary method of measuring vertical displacements.
Trigonometric leveling should be used when measuring the vertical displacements of foundations exposure to extreme heights (large mounds, deep pits, hillsides, etc.).
Hydrostatic leveling (portable or stationary device hose hydrostatic system, installed on the perimeter of the base) should be used to measure the relative vertical displacement of a large number of points, difficult to measure by other methods, as well as in cases where there is no direct line of sight between brands or when production site measuring activities of man can not stay for safety reasons.
Photogrammetric (stereophotogrammetric) method should be used to measure the sediment changes, banks and other deformations with an unlimited number of observed marks established for measurements in inaccessible places operating buildings and structures.
2. Horizontal displacement measurement techniques . Horizontal movement of foundations of buildings and structures shall be measured by one of the following methods or a combination of: casement observations; separate directions, triangulation, photogrammetry. Allowed to apply the methods and trilateration polygonometry.
Separate horizontal displacement measurement methods should be adopted according to the accuracy class, suitable for this method:
method of alignment of observations – I-III class;
method of separate directions – I-III class;
triangulation method – I-IV class;
photogrammetry method – II-IV class;
trilateration method – I-IV class;
method polygonometry – III-IV class.
The observations of alignment measurements of horizontal displacements of foundations should be applied in the case of rectilinear building (structure), or part of it and if possible, to ensure the sustainability of supporting characters end alignment.
The individual areas should be used to measure the horizontal displacement of buildings and structures if you can not fix the target, or sustain end alignment reference marks.
Triangulation method should be used to measure the horizontal movement of foundations of buildings and structures erected in rugged or mountainous terrain, and if you can not sustain supporting characters end alignment.
The Photogrammetry Photogrammetry is similar in method of measuring vertical displacements.
3. Measurement methods tilts. Tilt the basement (or building structures in general) should be measured by one of the following methods or a combination thereof: projection, coordinate, measure angles or directions, photogrammetry, mechanical methods using inclinometer, forward and backward pitches.
When measuring rolls foundation (buildings) by the projection should be used theodolites equipped with overhead level, or vertical projection devices.
When measuring tilts by coordination must install at least two supporting characters, which form the basis from which all the coordinates of the upper and lower points of the building (structure).
To measure bank buildings with complex geometric forms should use the measuring horizontal directions with two permanently fixed bearing signs arranged on mutually perpendicular directions (with respect to the building, construction).
To measure banks foundations for machines and installations in industrial buildings and structures to be applied, portable or stationary inclinometer for determining the slope of a degree or a relative measure.
Measurement tilt hydraulic structures should be done with the help of forward and backward pitches with a reading device, or device for the vertical projection [14].
Systematic monitoring of the development of cracks should be the appearance of a load-bearing structures of buildings and structures in order to clarify the nature and severity of the deformation of the object for further operation.
When monitoring the development of cracks on the long end should be periodically capture cross strokes applied paint, which appears next to the date of the inspection.
The observations of the crack opening width should use the measuring or holding devices that are attached to both sides of the crack: lighthouses, schelemery, which appears next to their numbers and the date of installation.
The crack width greater than 1 mm is necessary to measure its depth [14].
To analyze the deformation data DonNTU buildings, we need to know the conditions of their use.
3.3. The study of the operating conditions of buildings DonNTU
Academic buildings N1, N2 and N3 are located in the city of Donetsk, Voroshilovsky area and part of the main buildings of Donetsk National Technical University.
3.3.1. Brief description of the construction of educational buildings N1 and N2
The data on educational and laboratory buildings were taken from the Technical data sheet for civic buildings, provided the Bureau of technical inventory as of 30/07/2004, the case for number 1 and 30/01/2004 for building N2 [1, 2].
Building N1 built in 1932, this four-story high-rise building with a ground floor. Housing height of 22.40 m, length – 106 m, and the total area – 2689.6 m2. Case has three additions, and vestibule area of which is 360 m2, 174 m2, 141 m2, 7 m2 respectively.
For this case used cinder foundation of a board thickness of 300 mm and a length of 3500 mm, which established the panel in the form of through bezraskosnyh concrete trusses, having a thickness of 240 mm and a height equal to the height basement. On consumption of concrete, this construction is very economical, walls – breeze on reinforced concrete frame. Self-supporting longitudinal walls of the basement are based on projections of strip foundations cross walls.
Overlap in wooden casing, consisting mostly of beam elements that are part of the supporting structure, floor structure, filling mezhdubalochnogo designed for acoustic and thermal insulation, and finishing layer ceiling. Filling laminated, and each layer has its own purpose and is made of materials relevant to this purpose. The top layer of fill is the isolation, the lower – supporting insulated flooring, called coasting. The space between the joists is filled with insulation, laid by Nakata.
Roofing material – corrugated asbestos cement sheets. Hipped roof is a system of intersecting ramps – ramps.
Paul – boardwalk, which plank of battens 37 mm thick, is nailed to the joists of the boards or plates of 60 mm thickness. This type of sex suit at light loads with no hazardous processes in respect of fire, no wet processes. On separate floors and tiles used in bathrooms.
To fill window openings used window units.
Building N2 were built before 1917. The building consists of three high-rise floors and a basement. Buildings height is 20.1 m, length – 70 m, the area – 1575.8 m2.
Basic structural elements are the foundation of the type of rock – band. This type of foundation is ideal for facilities that have a low static load, but rather a high dynamic. Used for buildings up to 16 floors in soils with high regulatory resistance.
Walls – brick. Are durable, stable, have adequate thermal protection and sound insulation properties, fire-resistant, durable thanks to frost resistance, moisture resistance, biological resistance and resistance to corrosion.
In the second case as a slab of reinforced concrete slabs were used. Floors – plank and using ceramic tiles.
Filling window openings – wooden frames with double glazing. As in the building N1, the roof is covered with asbestos cement sheets, whose characteristics are durability, Non-incendive, light weight, a small number of seams, does not require a solid casing, cheap to operate. Roof – gable.
In the described cases pace stair made of precast concrete in the form of large-scale solid stairs and platforms. Housings contain water supply, sewerage, electricity, central heating water.
Blind area around the buildings is made of asphalt width of 1 m.
Information about the physical and mechanical characteristics of the soil foundation of building foundations in the original building did not survive.
Building N2 has a pronounced rectangular in plan, and the building N1 has a complex configuration.
3.3.2 General information about the building structure of educational building N3
Considered a three-story building complex configuration in terms of the basement under part of the building. Commissioned in 1938 [3, 4, 5].
The building is referred to the following classification groups:
on EASC 27751-88 это здание повышенного уровня ответственности;
process safety – safe production;
aggressiveness on labor – non-aggressive environment;
The total area of the building on the passport BTI is 25236.2 m2, где
7-storey part of the building – 5044.5 m2;
north wing (the building of the Vatutina ave.) – 3880 m2;
south wing (main entrance + military department) – 13144.2 m2;
central part (main facade) – 3167.5 m2.
Initial construction of the building was carried out in the mid-thirties.
During the war, the building was partially destroyed in the mid-forties restored. Design and built documentation for the construction and rehabilitation has not been preserved.
In the early sixties was made expansion of the building. The expansion project is designed Stalin affiliated institute Giprograd
.
Old part of the building structurally, is provided with an incomplete frame – bearing outer longitudinal walls and inner frame.
To the foundation to meet the following basic requirements: strength, resistance to tipping and sliding in the plane of the foundation base, countering the influence of ground and aggressive treatment, and the influence of weather (frost), compliance with the durability life of the building, industrial, and economic.
Foundations for exterior walls and columns of the building frame are made of monolithic reinforced concrete.
Columns and beams the building frame – reinforced concrete rectangular section. Column spacing of 6 m is called monolithic walls, made on-site construction by placing the mixture in light concrete formwork.
External wall fence of the building – brick masonry cement-sand mortar. Partitions – brick.
Covering – reinforced concrete on monolithic reinforced concrete beam.
Coverage – loft type of corrugated asbestos cement sheets on wooden rafters.
Filling window openings – wooden frames with double glazing. Wooden doors.
Floors in the classrooms and corridors of wood, in bathrooms with ceramic tiles in the entrance hall – concrete, mosaic.
North wing of the building is not fully constructive frame with bearing outer longitudinal walls and inner frame.
Foundations for the exterior walls of the building are made of precast concrete pads on the type series of II-03-02, under the internal columns frame – precast concrete pads a glass type [10].
The building is located in the coal-bearing areas in the west of the mine named M.I. Kalinin.
To sense the horizontal shear forces from the effects podrabotok pillows on top of the foundation in accordance with SDC B.1.1-5-2000 [6] provide reinforced concrete belt, shoes, linking the interior columns with foundations of the exterior walls.
Spatial rigidity of the building is provided by the joint work of the transverse and longitudinal walls and ceilings omonolichennyh through which transfer horizontal forces.
External wall fence of the building – masonry of silicate brick marks M75 cement-sand mortar grade M24. Partitions of plaster and cinder block and wood stoves.
Columns and beams inner frame buildings – steel reinforced concrete rectangular section. Column spacing of 6 m.
Covering – steel, concrete hollow core slabs on the type series of II-03-02.
The stairs and platforms – prefabricated, reinforced concrete.
Coverage – loft-type corrugated sheets asbestofanernyh the wooden rafters. Insulation – attic.
Filling window openings – wooden frames with double glazing individual manufacturing. Wooden doors in accordance with EASC 8750-58.
Floors in the classrooms and corridors – parquet, in bathrooms – ceramic tiles in the entrance hall – concrete, mosaic.
Blind area around the building – asphalt, width 1 m.
Data on the physical and mechanical characteristics of the soil foundation foundations of the building in the original building has been preserved.
Based on geological studies carried out Stalin Giprograd
branch in 1960 the foundation base of the building are tuning-shale with a rated impedance of 2.2 kg/cm2 and loam with a rated impedance of 2.5 kg/cm2 for the building [4].
To determine the deformation of the buildings and educational buildings DonNTU necessary to make their measurements. These measurements will be made at the summer 2013 students practice the third year of a specialty Engineering Geodesy
, after which they will be identified strain, as well as synthesis of long-term observations made to obtain a complete picture of these negative phenomena in time.
Conclusion
Normal operation of buildings and structures significantly complicate the structural damage, and sometimes this kind of damage and lead to a crash. Therefore, prevention and elimination of damage is one of the most important tasks in ensuring the normal operation of such facilities.
Definition changes strain the grounds and buildings of educational buildings DonNTU and incorporating the data needed to improve safety and further normal operation. To analyze the deformation data selected academic buildings DonNTU NN 1,2 and 3.
These buildings were built long ago and over time in mining, active geodynamic zones vibrations from vehicles and equipment, etc. require periodic diagnostics. To summarize the data on the deformation of buildings DonNTU necessary that measurements of these strains. These measurements will be carried out during the summer practice in 2013.
In writing this essay master's work is not yet completed. The estimated final completion in December 2013. The full text of the work and materials on the subject can be obtained from the author or his manager after that date.
References
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2. Technical passport of the academic building N2 DPI
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