Multilevel systems. Types and installation of prefabricated monolithic floors with your own hands

To reduce the cost of installing dividing structures between floors, modern technologies offer a private developer to use prefabricated monolithic floors. In the process of their installation, the crane is used only for lifting and laying blocks on a wall or crossbar, and subsequent operations are performed manually. Block products play the role of a permanent formwork, into which a concrete mixture is poured, obtaining a solid monolithic slab.

The system is a complex of lightweight reinforced concrete beams (they serve as a frame) and hollow ceramic blocks that fill the space between adjacent beams. When concreting, the lower part of the frame is poured with the mixture, after it hardens, the prefabricated floors become monolithic. Their positive properties are as follows:

tightness;
high level of protection of premises from noise;
low thermal conductivity;
readiness for cladding without making a second layer of screed - linoleum is laid directly on the floors, tiles and tiles are glued, laminate and parquet are mounted;
reduction in specific weight in comparison with a conventional reinforced concrete monolithic slab by an average of 35% (230-350 kg / m2);
the possibility of installation in inaccessible areas - this is important if a building is being reconstructed without dismantling the roof;
ease of joining with complex-shaped walls (with columns, ledges) - you can buy blocks with grooves or modify the floor elements right on the construction site;
plumbing and electrical communications easily fit into voids.

Although the installation of prefabricated monolithic structures is laborious, the economic effect from the use of the new technology is quite significant due to the fact that the cost of light beams and blocks, the cost of their transportation and installation, is reduced.

Installation of precast-monolithic often-ribbed floors can be performed using standard elements produced by the industry.

Reinforced concrete beams with a section of 20x20 cm, lengths from 3 to 6 m.
Bearing girders are lightweight trusses with a lower concrete belt (its section is 5.5 x 12). Depending on the bearing capacity of the rods of the lower belt, trusses are divided into 2 types - for a total design load of 1300 kg / m2 and 900 kg / m2. The purlins are produced in three sizes: 2.86 m long (weight 50 kg); 4.36 m (74 kg); 5.86 m (100 kg). The desired product is selected by the size of the span and overlap (3, 4.5 or 6 m).
Blocks. They are most often made from expanded clay concrete or from polystyrene concrete.

Popular prefabricated monolithic floor systems

In Russia, there is a demand for sets of standardized parts and assemblies, which make it possible to significantly speed up installation work. The main characteristics of the most well-known floor systems are proposed for consideration.

1. Teriva. These Polish-made systems have been used in Europe for over 20 years and include reinforced concrete beams and hollow blocks. The load-bearing capacity of the floor is 400 kg / m2, while the thickness of the structure is only 24 cm. The main parameters of the system are as follows:

length of beams - from 1.2 to 8.6 m;
the interval between the axial lines of the beams is 0.6 m;
concrete layer thickness - 3 m;
the thickness of the monolithic floor slab is 24 cm;
the minimum amount of support on the wall is 8 cm;
weight of one block - 17 kg;
specific weight of beams - 12 kg / rm;
finished floor weight - 260 kg / m2.

For the manufacture of 1 m2 of the overhead structure, 6.7 blocks, 1.7 m of beams, 0.6 m3 of concrete are required.

2. Ytong. The main elements of the system are light reinforced concrete beams with free reinforcement and T-shaped blocks made in the form of inserts resting on the beams with lateral grooves. The bearing capacity of the Itong brand slab reaches 450 kg / m2, but its main technical parameters:

beam dimensions - 4 x 12 cm, length - up to 7 m (production of products has already begun, allowing to cover 9-meter spans);
the distance between the axes of the beam elements is 0.68 m;
reinforcement diameter: top - 8 mm, bottom - 12 mm, additional - from 6 to 16 mm;
the specific weight of the beam is from 13 to 17.2 kg (depending on the diameter of the reinforcement);
dimensions of the main unit - 60 x 20 x 25 cm; additional - 60 x 25 x 10 cm;
specific weight - 500 kg / m3.

3. Domestic systems of Marko. They include reinforced concrete beams (trusses) with a three-dimensional triangular frame made of reinforcing bars, polystyrene blocks, and reinforcing mesh. The following are the characteristics of the overlap.

Beams. The maximum length of the products is 12 m, the height of the frame is 15 or 20 cm. The dimensions of the concrete base of the beams are 4x12 cm. The weight of a running meter of the farm is 12.7-17.4 kg / running meter. 2 types of beams are produced: with completely hidden upper and lower reinforcement (for bearing on load-bearing walls); with free reinforcing ends - for embedding a load-bearing wall into a monolithic belt.

Reinforcement: top diameter - 8 mm, bottom - from 6 to 12 mm, additional (for the lower belt) - from 6 to 16 mm.

Blocks. The density of polystyrene concrete is no more than 400 kg / m3, therefore the weight of the hollow product is small - about 7 kg. There are two height options (150; 200 mm) and several configuration options:

standard (BP-200, BP-150);
thin-walled (BPTS);
arched with a radial cut;
arched with trapezoidal selection;
plug (BPZ-200, BPZ-150).

Marco's floor thickness varies from 200 to 350 mm. To increase the bearing capacity, according to the project, additional foam plates with a thickness of 5 or 10 cm are used, which are glued to the blocks with any tile adhesive.

Installation of prefabricated ceiling structures in steps

For work, you will need a minimum set of tools and auxiliary materials: a hammer, a sledgehammer, a puncher, a building level, a tape measure, a knitting wire, a vibrator. To build prefabricated monolithic floors with your own hands, you need to perform a number of sequential operations.

1. The walls are cleaned of debris, a frame base made of reinforced concrete beams is laid on them with the help of cement mortar, placing temporary supports under them. If the floor length is 4.5 m, one support is placed under the beam; for a 6-meter beam, at least two of them are needed. It is allowed to lay blocks directly on the masonry wall.

2. Hollow concrete blocks (formwork) are placed on the frame, and longitudinal girders are placed between them. In this case, the block elements are arranged in transverse rows, preventing one-sided overloading of the girders and observing the minimum intervals between adjacent blocks.

3. A reinforcing mesh is laid on top of the formwork. The blocks have T-grooves that can be additionally reinforced with fiberglass whips.

4. The mesh strips are laid with an overlap of at least 15 cm (according to the SNiP regulations for individual construction), fastened with a knitting wire to the upper part of the girders.

5. The top of the structure is poured with heavy concrete of a class not lower than M250 (grade from B154), prepared with the addition of fine-grained sand. The composition of the concrete mix must comply with GOST 27006-86.

6. During the curing period, the monolithic slab is regularly moistened to avoid drying out and cracking. When the concrete is completely cured (after about 72 hours), the joist supports are removed.

When making prefabricated structures on your own, it is imperative to compact the concrete (manually or using a vibrating tool) in order to achieve maximum adhesion of the solution to the beams and girders. For pouring, you can use foam concrete: it quickly hardens and gains strength, has a low moisture permeability.

Prefabricated structures of polystyrene blocks have the smallest weight, having voids in the lower part that remain even after filling with concrete. The upper monolithic part, together with the armature belt, works in compression and takes on the working load.

The cost of prefabricated monolithic floors

When choosing a floor option, take into account its bearing capacity, the size of the overlapping area and the configuration of the walls. To make the purchase profitable, they study the system of discounts from the supplier and the cost of delivery. The table shows prices for systems of popular brands and components for their assembly in Moscow and the capital region.

TRENDS IN THE STRUCTURAL CONSTRUCTION OF OS

As noted above, in order to meet the requirements for a modern OS, its structural design is of great importance. Operating systems have come a long way from monolithic systems to well-structured modular systems capable of evolving, expanding, and easily porting to new platforms.

In general, the "structure" of a monolithic system is a lack of structure (Figure 38). The OS is written as a set of procedures, each of which can call the others when it needs it. With this technique, each procedure in the system has a well-defined interface in terms of parameters and results, and each is free to call any other to do some useful work for it.

Figure 38 - Monolithic OS structure

To build a monolithic system, you need to compile all the individual routines and then link them together into a single object file using a linker (examples include earlier versions of the UNIX kernel or Novell NetWare). Each procedure sees any other procedure (as opposed to a structure containing modules, in which most of the information is local to the module and module procedures can only be called through specially defined entry points).

However, even such monolithic systems can be somewhat structured. When accessing system calls supported by the OS, parameters are placed in well-defined places, such as registers or the stack, and then a special interrupt command is executed, known as a kernel call or a supervisor call. This command switches the machine from user mode to kernel mode, also called supervisor mode, and transfers control to the OS. The OS then checks the call parameters to determine which system call should be executed. The OS then indexes the table containing the procedure references and calls the corresponding procedure. This OS organization assumes the following structure:

1. The main program that calls the required service routines.

2. A set of service procedures that implement system calls.

3. A set of utilities serving service procedures.

In this model, there is one service routine for each system call. The utilities perform functions that are needed by several service procedures. This division of the procedures into three layers is shown in Figure 39.

Figure 39 - Simple structuring of a monolithic OS

MULTI-LEVEL SYSTEMS

The generalization of the previous approach is the organization of the OS as a hierarchy of levels. Levels are formed by groups of operating system functions - file system, process and device management, etc. Each level can interact only with its immediate neighbor - higher or lower level. Application programs or modules of the operating system itself pass requests up and down these layers.

The first system built this way was the simple package system THE, which Dijkstra and his students built in 1968.

The system had 6 levels. Level 0 was concerned with allocating processor time, switching processes on interrupt or after a timeout. Level 1 managed memory - allocated RAM and space on a magnetic drum for those parts of processes (pages) for which there was no room in the OP, that is, layer 1 served as virtual memory. Layer 2 handled communication between the operator console and processes. With this layer, each process had its own operator console. Level 3 controlled and buffered I / O devices to and from them. With Layer 3, each process, instead of dealing with specific devices with their varied features, turned to abstract I / O devices with user-friendly characteristics. At level 4, there were user programs that didn't have to worry about processes, memory, console, or I / O management. The system operator process was located at level 5.

In THE system, the layering served mainly for development purposes, since all parts of the system were then assembled into a common object module.

A further generalization of the multi-level concept was done in the MULTICS OS. In a MULTICS system, each layer (called a ring) is more privileged than the one above. When a higher-level procedure wants to call a lower-level procedure, it must execute the appropriate system call, that is, a TRAP (interrupt) command whose parameters are carefully checked before the call is made. Although the OS in MULTICS is part of the address space of each user process, the hardware provides data protection at the level of memory segments, allowing, for example, write-only access to some segments and read or execute access to others. The advantage of the MULTICS approach is that it can be extended to the structure of custom subsystems. For example, a professor can write a program to test and evaluate student programs and run that program at level n, while student programs will run at level n + 1, so they cannot change their grades.

A layered approach has also been used in the implementation of various UNIX variants.

While this structured approach has usually worked well in practice, today it is increasingly seen as monolithic. In systems with a multi-level structure, it was not easy to remove one layer and replace it with another due to the multiplicity and blurred interfaces between the layers. Adding new features and modifying existing ones required a good knowledge of the operating system and a lot of time. When it became clear that operating systems were long-lived and needed to be able to evolve and expand, the monolithic approach began to crack and was replaced by the client-server model and the closely related microkernel concept.

The use of built-in building systems is one of the methods to increase the reliability, durability and capital of a building. The built-in system can be implemented in prefabricated, monolithic and precast-monolithic versions. The main distinguishing feature of the built-in system is that it has independent foundations, therefore it itself perceives all the technological and operational loads, partially or completely freeing the wall enclosing structures from them. This makes it possible to carry out the superstructure of the building regardless of the bearing capacity of the old foundations and wall railing, significantly reduce the amount of work on strengthening the foundation, strengthening the existing foundations and walls.

The use of built-in systems allows you to create a more rational layout of premises, provide modern comfort in them, apply progressive materials and structures, carry out reconstruction using modern construction technologies with equipment and the necessary mechanization means. It is important to design for a reconstructed building in the cramped conditions of urban development not only of modern structures, but also of a rational work technology.

Precast concrete embedded systems.Buildings that are rectangular or close to it in plan are most suitable for implementing the embedded installation method. Inspection of a building allows you to evaluate its structure and determine the use of structural schemes with complete and incomplete embedded frames. Full built-in frame allows stress relief from

enclosing walls, which creates the preconditions for reconstruction work not only with a complete redevelopment, but also with a superstructure of several floors. When using an incomplete frame, when the load from it is partially transferred to the outer walls, the possibility of superstructure is limited by the bearing capacity of the foundations and outer walls.

Embedded installation technology provides for the complete dismantling of ceilings, partitions and other elements, leaving only the external load-bearing walls and, less often, the walls of the stairwells. It is advisable to take a separate section of the building for the capture. With the in-line method of erecting a built-in incomplete frame (external longitudinal walls carry the load from the frame), it is advisable to have four independent flows:

Installation of foundations for the middle longitudinal row of columns;

Preparation of supports for crossbars in external brick walls;

Installation of columns, girders, stiffening walls and floor slabs;

Installation of sanitary cabins, ventilation blocks, flights of stairs and landings, walls of elevator shafts.

When using a full frame with a building superstructure, the same four assembly flows can be adopted to organize the work. But a significant increase in the load from the added floors requires the installation of a monolithic foundation slab under the entire building with sub-columns under three rows of columns or the installation of glass-type foundations under all columns.

Prefabricated monolithic embedded systems.For reconstructed rectangular buildings with weakened external load-bearing walls, an embedded system can be used, including monolithic internal longitudinal and

transverse load-bearing walls and prefabricated slabs made of prestressed hollow-core decking. Long flooring allows to reduce the specific consumption of materials and create free planning volumes of significant sizes.

The system additionally provides for prefabricated elements of staircases, elevators, sanitary cabins, other built-in elements and monolithic wall diaphragms of the end elements of buildings.

Monolithic embedded systems.Monolithic embedded systems are more flexible than prefabricated ones and can be recommended for buildings with curved and complex shapes with different floor heights.

If the old design scheme is preserved in the building being reconstructed without a superstructure, then the built-in monolithic frame will be a two- and three-span system

with intermediate supports in the form of columns or wall elements with the support of the erected monolithic floors on the existing external walls. When building a building on several floors, it is necessary to arrange independent foundations for the entire embedded system, in this case the outer walls practically turn into self-supporting and enclosing ones.

The main advantages of the monolithic option:

Reduced material consumption due to more complete use of continuous systems;

Lack of butt joints;

High flexibility of space-planning solutions of buildings;

Mechanization of work without the use of mobile and tower cranes;

The space-planning solution of the building is not the main one when deciding on its reconstruction.

In connection with the widespread introduction of modern formwork systems into the construction practice, it became possible to significantly reduce labor costs for all complex concreting processes.

operating system Is an ordinary program, so it would be logical to organize it in the same way as most programs, that is, to be composed of procedures and functions. In this case, the components operating system are not independent modules, but constituent parts of one large program. Such a structure operating system called monolithic core (monolithic kernel). A monolithic kernel is a collection of procedures, each of which can call each. All procedures work in privileged mode. In this way, monolithic core - this is such a scheme operating system, in which all its components are constituent parts of one program, use common data structures and interact with each other by directly calling procedures. For monolithic operating system the kernel is the same as the entire system.

In many operating systems from monolithic core the assembly of the kernel, that is, its compilation, is carried out separately for each computer on which it is installed operating system... In this case, you can select a list of hardware and software protocols, support for which will be included in the kernel. Since the kernel is a single program, recompilation is the only way to add new components to it or exclude unused ones. It should be noted that the presence of unnecessary components in the kernel is highly undesirable, since the kernel is always completely located in RAM. In addition, the elimination of unnecessary components improves reliability operating system generally.

Monolithic Kernel - The Oldest Way to Organize operating systems... An example of systems with monolithic core is most Unix systems.

Even in monolithic systems, some structure can be distinguished. As in a concrete block, it is possible to distinguish inclusions of gravel, and in the monolithic core, inclusions of service procedures corresponding to system calls... Service procedures run in privileged mode, while user programs run in unprivileged mode. To switch from one privilege level to another, the main service program can sometimes be used, which determines which system call was made, the correctness of the input data for this call and transfers control to the corresponding service procedure with the transition to the privileged mode of operation. Sometimes a set of software utilities is also distinguished that help to perform service procedures.

Layered systems

Continuing the structuring, it is possible to split the entire computing system into a number of smaller levels with well-defined connections between them, so that N-level objects can only call N-1 level objects. The lower level in such systems is usually hardware, and the upper level is the user interface. The lower the level, the more privileged commands and actions the module at this level can perform. For the first time this approach was applied when creating the THE (Technishe Hogeschool Eindhoven) system by Dijkstra and his students in 1968. This system had the following levels:

Figure: 1.2.

Puff systems are well implemented. When using bottom layer operations, you don't need to know how they are implemented, you just need to understand what they do. Puff systems are well tested. Debugging starts from the bottom layer and is done in layers. When an error occurs, we can be sure that it is in the tested layer. Puff systems can be easily modified. If necessary, you can replace only one layer without touching the rest. But layered systems are tricky to design: it is difficult to correctly determine the order of the layers and what belongs to which layer. Puff systems are less efficient than monolithic systems. So, for example, to perform I / O operations, the user program will have to sequentially traverse all layers from the top to the bottom.

Virtual machines

At the beginning of the lecture, we talked about looking at operating system How on virtual machinewhen the user does not need to know the details of the internal structure of the computer. It works with files, not magnetic heads and a motor; it works with huge virtual, not limited real RAM; he doesn't care much whether he is the only user on the machine or not. Let's consider a slightly different approach. Let be operating system implements virtual machine for each user, but not simplifying his life, but, on the contrary, complicating it. Each such virtual machine appears to the user as bare metal - a copy of all the hardware in the computing system, including the processor, privileged and unprivileged commands, I / O devices, interrupts, etc. And he is left alone with this iron. When you try to access such virtual hardware at the level of privileged commands, in fact, a system call occurs to the real operating system, which performs all the necessary actions. This approach allows each user to upload their own operating system on virtual machine and do with it whatever your heart desires.

Figure: 1.3.

The first real system of this kind was CP / CMS, or VM / 370 as it is now called, for the IBM / 370 family of machines.

The disadvantage of such operating systems is a decrease in efficiency virtual machines compared to a real computer, and they are usually very bulky. The advantage lies in the use of programs written for different operating systems.

Microkernel architecture

The current trend in development operating systems consists in moving a significant part of the system code to the user level and simultaneously minimizing the kernel. It's about an approach to building a kernel called microkernel architecture (microkernel architecture) operating systemwhen most of its components are independent programs. In this case, the interaction between them is provided by a special kernel module called a microkernel. The microkernel operates in a privileged mode and provides interaction between programs, processor scheduling, initial interrupt handling, I / O operations, and basic memory management.

Figure: 1.4.

The rest of the system's components communicate with each other by passing messages through the microkernel.

The main advantage microkernel architecture - high degree of kernel modularity operating system... This makes it much easier to add new components to it. In micronucleus operating system without interrupting its operation, you can load and unload new drivers, file systems, etc. The process of debugging kernel components is greatly simplified, since a new driver version can be loaded without restarting the entire operating system... Kernel components operating system do not fundamentally differ from user programs, so you can use conventional tools to debug them. Microkernel architecture improves system reliability because a bug at the unprivileged program level is less dangerous than a crash at the kernel mode level.

In the same time microkernel architecture operating system introduces additional messaging overhead that significantly impacts performance. To micronucleus operating system the speed was not inferior operating systems on the base

Lecture 2

Trends in the structural design of operating systems

Monolithic systems

In general, the "structure" of a monolithic system is a lack of structure. The OS is written as a set of procedures, each of which can call the others when it needs it. With this technique, each procedure in the system has a well-defined interface in terms of parameters and results, and each is free to invoke any other to do some useful work it needs.

a) the main program that calls the required service procedures;

b) a set of service procedures that implement system calls.

C) a set of utilities serving service procedures.

Multilevel systems

The first system built in this way was the simple package system THE, which Dijkstra and his students built in 1968. The system had 6 levels. Level 0 was concerned with allocating processor time, switching processes on interrupt or after a timeout. Level 1 managed memory - allocated RAM and space on a magnetic drum for those parts of processes (pages) for which there was no room in the OP, that is, layer 1 served as virtual memory. Layer 2 handled communication between the operator console and processes. With this layer, each process had its own operator console. Level 3 controlled and buffered I / O devices to and from them. With Layer 3, each process, instead of dealing with specific devices with their varied features, turned to abstract I / O devices with user-friendly characteristics. At level 4, there were user programs that didn't have to worry about processes, memory, console, or I / O device management. The system operator process was located at level 5.

In THE system, the layering served mainly for development purposes, since all parts of the system were then assembled into a common object module.

A layered approach has also been used in the implementation of various UNIX variants.