Course project "Concrete Engineering"

Contents

Introduction

1. Design Task

2. Source Data

3. Calculation of scope of main and related works

4. Layout of formwork forms with development of layout diagrams of panels and power elements of formwork

5. Development of options for concreting of structures and their organization diagrams

6. Selection of work methods

6.1. Formwork

6.2. Reinforcement works

6.3. Development of options for concreting of structures and their organization diagrams

7. Determination of feasibility indicators and justification of accepted version of works execution

8.Technology of complex process of construction of monolithic foundations with development of process diagrams

8.1. Reinforcement works

8.2. Formwork

8.3. Transportation of concrete mix, formwork, reinforcement

8.4. Concrete works

8.4.1. Supply and laying of concrete mixture in structures

8.4.2. Concrete Care

8.5. Disassembly and removal of formwork of structures

9. Production costing

10. Development of the planning plan for the complex foundation concreting process

11. Safety precautions during works

12. Technical and economic indicators

List of literature used

Introduction

Concrete and reinforced concrete works are one of the main types of construction. In the total cost of material resources consumed in capital construction, the cost of concrete and reinforced concrete works is about 25%.

The main areas of improvement of capital construction are reducing the time and cost of construction, as well as reducing labor costs. This is achieved mainly due to the further improvement of the organization of construction, the use of advanced technology for the construction of buildings and structures and the complex mechanization of processes.

Layout of formwork forms with the development of schemes for arrangement of boards and power elements of formwork.

For our foundations we choose steel panels of the formwork "Monolit77" foundations for the framework of the building. Single formwork boards are combined into one common panel of the foundation side with the help of fights that give the panel the necessary strength and rigidity. In corners the boards are connected to each other by means of mounting corners.

The fights are installed, first of all, along the lower faces of the first stage of the foundation. For the second and third stages, they serve as supports transmitting a load to the upper face of the underlying stage. The fights are located in the form of a "mill." This connection is considered more reliable and economical. Fights and shields are connected to each other by hooks with wedge-shaped constipations. All the constituent elements of the formwork: shields, fights, corners, etc., are summarized in Appendix 1.

Selection of work methods

6.1. Formwork.

The formwork consists of prefabricated elements delivered to the construction site by road.

Unloading is performed by MTT16 crane available on the construction site.

Assembly of the first and second stages of foundation formwork is done manually, directly at the foundation installation site, and the upper part is assembled at the pre-assembly site and installed in the design position by MTT16 crane available on the construction site.

Assembly of formwork forms from the Monolith-77 inventory metal formwork sheets is carried out at the foundation installation site, starting from the lower box, as well as at the pre-assembly site, is assembled by connecting corner sheets using mounting angles and further building up the parent sheets.

Rebar is represented by grids of various sizes.

Unloading is performed by MTT16 crane available on the construction site.

Finished bottom grids are installed manually on concrete liners with the thickness of the protective layer, before installation of the lower foundation box.

The sub-column reinforcement is assembled at the pre-assembly site, from finished grids and rods prior to installation of the formwork box and is installed in the design position by the crane available at the construction site.

To ensure design thickness of protective layer of concrete on reinforcement industrial fixators. Intersection of reinforcement rods is connected to each other by manual electric arc welding.

Reinforcement works

Reinforcement products of foundations - grids, frames and individual rods, depending on their weight and size, are installed in the design position manually and by crane, with assembly and enlargement directly in place. Lower grids are installed in the form of finished products on cement or concrete linings with the thickness of the protective layer in accordance with the layout scheme after installation of the formwork of the lower stage of the foundation.

The sub-column reinforcement is previously assembled from separate vertical rods and separate horizontal rods on the site for pre-assembly near the installation site in the area of the installation crane. Installation is performed by crane into preparatory formwork form before installation of formwork box. To fasten the grids to each other and make them stable and rigid, separate parts of the grid and the frame are welded to each other by seams or attached to tacks

To ensure the design thickness of the protective layer of concrete, pre-made cement or cement-sand gaskets are tied to reinforcement bars. Crossings of reinforcement rods are connected to each other by manual electric arc welding in the form of tacks.

Formwork

During formwork of stepped foundations, work is carried out in two stages. The lower part of the formwork is assembled directly at the position of the foundation. And the upper part is first enlarged at a special site in the immediate vicinity of the installation site, and after that the finished unit is supplied and installed in the design position by a crane .

Position of longitudinal and transverse axes, center of foundation, its side surfaces, elevation of bottom are determined prior to assembly of formwork and beacons are installed. Hairlines are applied with indelible paint on the basis of concrete preparation. Assembly of formwork forms from the inventory small-panel formwork at the foundation installation site begins with the installation of lower boxes: corner panels are installed and fixed using mounting corners, then the remaining panels of the lower box are increased to them. Hairlines fixing position of second stage shields are applied on ribs of lower box shields.

According to risks, pre-assembled formwork panels are installed, connecting the fights "into the mill," they are attached to the lower box with strubcins. Assembled second box is straightened along axes. For ease of installation of operation during assembly of overlying boxes, temporary working floorings are laid on the lower box, from which the box of formwork of the next stage is assembled in the same order. The formwork of the sub-column is assembled in the same way as the second stage. It ends with attachment of the form of the cup-maker to the upper box of the sub-column with strubcins. This is done from curtain scaffolding.

The glass formwork is adjusted along axes and elevations. When installing the unit, its design position is monitored. To do this, the risks applied to the lower stage of the formwork are combined with the risks present in the concrete preparation. Special attention is paid to proper installation of formwork unit by height. If the level of concrete preparation does not correspond to the design elevation of the bottom of the foundation, special beacons are arranged, which serve as supports for the formwork of the foundation block. The work on the assembly of the formwork is carried out by a link of two people .

Supply and laying of concrete mixture in structures.

Concrete mixture is supplied to the structure using SB126A auto concrete pump. In order to avoid delamination of concrete mixture, it is not allowed to freely drop it in the foundation structure from a height of more than 3.54m. It is necessary to use "speed dampers" - probes, vibrochobots, rubberized tarpaulins, hoses of large diameter .

It is allowed to lay the concrete mixture in a formwork mould after fulfillment of the necessary requirements for preparation of the structure base for concreting. The surface of the rock soil should consist of healthy unwaved rock. Cracks are sealed with mortar or concrete mixture, overburdens in rock bases should be filled with a mixture corresponding to concrete of low grades.

When preparing the soil base, all silty, vegetable, peat and other soils of organic origin should be removed from it. The dry soil of the base before laying the concrete mixture is slightly moistened. Soil overruns below the design elevation shall be filled with sand with careful compaction.

A concealed work certificate shall be drawn up on the readiness of the base for laying the concrete mixture.

The concrete mixture is laid in the structure in horizontal layers of approximately the same thickness. The overlapping of the previous layer of concrete mixture shall be performed prior to the start of setting of the mixture in the previous layer.

Glass-type foundations are concreted, as a rule, without forming working joints, but before laying the concrete mixture in the upper stages, a short technological break must be made to lose the mobility of the previously laid mixture in order to avoid its extrusion through the open top of the formwork.

Compaction of the concrete mixture is the main technological operation in concreting, the quality of which depends on the density and uniformity of the concrete, and therefore its strength and durability. When concreting foundations, concrete mixture is compacted with internal (depth) vibrators.

For this project, IV75 depth vibrator is selected for compaction of concrete mixture. With tip d = 28mm

Concrete care.

Care for freshly laid concrete should be started immediately after the concrete mixture is laid and carried out until 70% of the design strength is reached.

The freshly laid concrete mixture shall be protected from dewatering during the initial period. When concrete reaches a strength of 0.5 MPa, its subsequent care should consist in ensuring the wet state of the surface by means of the device of moisture-intensive coating and its moistening, holding the open surfaces of concrete under a layer of water, continuous spraying of moisture over the surface of structures. At the same time, periodic watering of open surfaces of hardening concrete and reinforced concrete structures is not allowed.

In dry hot weather, it is also recommended to water the formwork, and cover the open surfaces with a steam-proof light film.

When holding concrete in structures, it is necessary to provide a set of measures that ensure the protection of concrete in the initial period of its hardening from impacts, shocks and damage. This is especially true for early fracturing of structures. Structures are expanded after concrete reaches strength ensuring preservation of corners, edges and surfaces. The terms of decay depend on the mode of hardening and the grade of concrete, the type of cement, the structural features of the elements and are established by the project of work.

Disassembly and removal of formwork of structures.

Unloaded monolithic structures shall be expanded with condition of maintaining the shape of vertical surfaces when concrete strength is reached, according to SNiP, not less than 1.01.5 MPa.

Formwork is disassembled in reverse sequence of its assembly. Joints fixing angular elements are loosened. With the help of a slice or jacks, the walls of the cup are torn from concrete, the cup is removed, the attachment of the corner joints of the formwork of the stages is weakened, after which the panels are torn from the concrete by the same method. Dismantled unit or panel is lifted by mounting loops on fights and temporarily installed away from finished foundation.

Production costing.

According to the selected version, the composition of the performed works is specified: loading and unloading, reinforcement, welding, formwork, as well as laying of concrete mixture in the structure with the solution of issues of compaction, care of concrete and removal of formwork. Production calculation is made for the listed processes according to ENiR [5,6,7]. (Annex 3)

Development of a schedule for the complex process of foundation concreting.

The work schedule reflects the sequence and organization of processes in the complex of concrete works with conditionally consists of two parts. The first part in the form of a table includes all engineering calculations, and the second reflects the sequence and duration of work with the indication of the calendar time of the start and end of individual processes, as well as their relationship.

The basis for the first part is the production costing data and process diagrams. At the same time, it is taken into account that machines and people should work throughout the process with the implementation of production standards by 100115% of the normative.. The results are summarized in Annex 4

534b879cef88c-_________________.dwg