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METHODS OF TECHNICAL SURVEYS OF BUILDINGS AND STRUCTURES

Company Vitan-Estate offers a wide range of services in the field of technical surveys of buildings and structures. Unlike the design of new constructions, reliability is ensured only by calculating and monitoring the quality of existing data are used for the operational status of the designs, test calculations, as well as tests in the working position. In addition, during the operation of the structures there is a need to establish the possibility of using them for other purposes under specific conditions and for a certain period to be determined projected operating conditions or reconstruction. This can be fixed by technical survey of buildings and structures by checking the reliability and durability of structures. Recently, such a regulatory procedure is called “assessment of technical condition of structures“.

Technical survey of buildings and constructions is a separate kind of construction activities. The need for technical survey is caused by physical and moral wear and tear of the building structures and changing conditions, as well as a lack of construction standards explicitly accounting for the time factor. In other words, ensuring operability designs to a specific point in its existence requires a set of activities that vary from design, manufacture and installation of building elements related to the establishment of industrial buildings and constructions of living conditions of enterprises and, above all, the safety of the process of exploitation.

According to DBN 362-92 and in accordance with GOST 27751-88 depending on the ability of structures to carry out functions stipulated by normative and design documentation, technical survey after their condition may be classified:

-correct-if all of the requirements, standards and State standards;

-healthy-with partial derogation from the requirements of the project and existing norms, but without violating the requirements of the limit state of the first group, as well as in violation of the requirements of the second group, does not restrict the normal functioning of the production;

-limited healthy-a condition in which the provision of technological process is carried out under the control of State structures; the limitation on the duration of exploitation and restriction of technological process parameters.

-emergency-with existing violations of the requirements of the first group of limit States.

Evaluation of technical condition, in principle, all structural elements associated with human activity, and in areas such as engineering, instrumentation, aerospace and so on have sufficiently developed regulatory procedures. Building constructive elements of this assessment are exposed to relatively recently and have a number of distinctive features, very hampering the development of such procedures. Such characteristics include: a huge variety of constructive forms, hampering the development of joint approaches, considerable uncertainty calculation models associated with the probabilistic nature of the materials, loading and operating conditions, in most cases, the workability of the factor cannot be verified by direct methods.

The main issue is the interpretation of the technical condition evaluation results of work to identify the operational status of the designs. At this stage of development of building constructions, diagnostic assessment of technical condition of any constructive form can be implemented in the following main methods:

1.     Comparison of defects and damages of the constructive form with valid values, enshrined in the norms or projects.

2.     Estimated impact assessment of defects and damages on the carrying capacity of the structures.

The first method can be considered to be technical Diagnostics package. According to the accepted terminology under technical Diagnostics refers to 100% control of “object”. If it is not possible to 100% control of the technical examination is performed, it is believed that technical examination may not give a true picture of the State of the designs, because the regulatory health settings may not match with real. With regard to building elements, it can be argued that the pure technical diagnostics as 100% control of the object almost impossible in view of the large amount of building structures, lack of continuity material typical of engineering structures and the lack of strict health check methods. The need to assess the health of ensuring desired reliability allows you to split the object evaluation of technical condition of the following parts:

1. The material structures.

2. Connection elements.

3. Structures and their elements.

The material and links with known limitations of technical Diagnostics has the means to implement it. For most designs and components for the foregoing reasons, technical Diagnostics can be applied as a special case.

Thus, the first method for technical surveys of buildings and structures should be seen as a development of the second method, i.e. types of deviations in advance known, made their calculated score and determined their maximum allowable values, usually in tabular form. So, for example, is carried out at the factory. designs acceptance Unfortunately, now it is almost impossible to assess the impact of a deflection on bearing capacity without taking into account the specific conditions and recalculation.

To develop normative materials first method would require a significant amount of research summarizing their results. Thus, the task of the assessment procedure of the technical condition is to develop methodologies, including accounting, as the technical condition of structures, and their conditions of use. In some circumstances, sufficient so designs can be used both methods.

Use the second method as the main structural parts involves the following procedures for the evaluation of the technical condition:

1.     Full-scale survey of building elements to detect their actual status and operating conditions.

2.     Validation calculations taking into account the results of the field studies.

3.     Assessment of technical condition with the establishment of the possibilities and conditions of operation of the structures.

4.     Repair and reinforcement using residual bearing capacity of structures.

The last paragraph directly from the assessment of the technical state is not bound, however, the granularity of the works on the first three items, especially emergency facilities is largely determined by the knowledge, methods and techniques of restoration designs.

Field studies involve the collection of data about the condition of structures and can be divided into the following parts:

1.     Clarification of characteristics of materials. The need for such refinement is defined by the probabilistic design adopted when designing new structures, and specific characteristics that are implemented in the design. It is possible to reject, as in most, and downwards. In addition, material characteristics change over time: fatigue, aging, etc.

2.     Clarification of the loads and impacts. This necessity is dictated by the difference of the loads that are implemented in the process of exploitation, adopted when designing.

3.     Technical Diagnostics or field inspection structures aimed at detecting defects and damages, as well as quantification structures.

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