Masonry, as an important construction method in the field of construction, has evolved for thousands of years and provides solid support for buildings all over the world. However, the passage of time and the influence of natural forces have made the masonry structure gradually fragile, exposed to risks and crises. In order to ensure the safety of the building and maintain the safety of the lives and property of the residents, the safety appraisal of masonry structures has become a crucial task.
At present, the stock of masonry structures with poor overall safety performance and poor seismic resistance still has a high proportion, and there are large potential safety hazards in the vast number of rural self-built houses, and the structural safety detection and identification of masonry structures and the investigation of safety risks are an important direction of China's structural safety testing and identification work.
Next, let the city test give you a brief introduction to some relevant knowledge of masonry structure safety identification!
01. Why does the masonry structure need to be appraised for safety?
Component material strength Mass is missing.
Due to the influence of construction quality, time and environmental factors, the material performance of the components gradually decreases, and even cannot meet the requirements of the current relevant specifications, such as the actual strength of the brick and mortar materials of the load-bearing wall does not meet the design requirements, the actual concrete strength of the structural column and ring beam is not up to standard, the alkali corrosion of the load-bearing wall of the masonry structure house, the pulverization of the brick block, and the serious decay and cracking of the wooden components.
Approaching or reaching the end of its design life.
Part of the masonry structure building is about to reach or has reached its design service life, but is still in use, the structural form, material performance, seismic measures, etc. of this kind of masonry structure have long not met the current seismic fortification requirements, durability and safety are greatly reduced, and the use function is affected and there are great potential safety hazards.
The technical level of the construction team is low, and the quality is not guaranteed.
Many masonry structures were built in the first decade of the 20th century, when the overall level of the construction team was low, and the quality control was not in place. It is not uncommon for wall masonry mortar to be pulverized, the ash joints are hollow, the "experience mix ratio" concrete, and the cracks caused by leakage and warping cracks on the building roof are not uncommon.
The construction dossier is incomplete.
The filing of survey reports, construction drawings, as-built drawings and project acceptance documents, renovation and additions can realize the continuous control of the health status of the building, which is conducive to the regular self-inspection and investigation of housing safety hazards, and the rapid implementation of detection and identification, and also provides data basis for subsequent reinforcement design and transformation.
In the early stage of the construction of some masonry structures, the main purpose of the construction units was to complete the construction tasks in a hurry, and they did not pay attention to the formation, accumulation, and management of archival materials, resulting in incomplete archival materials for some projects.
02. Safety appraisal method for masonry structure.
The safety appraisal of masonry structure is divided into three levels, and each level is divided into four levels:
1. Component safety appraisal (one floor): The safety appraisal of structural components is in accordance with the "Civil Building Reliability Appraisal Standard" GB 50292-2015, which is comprehensively evaluated according to the four aspects of the components (i.e., bearing capacity, structure, displacement and cracks or other damage that are not suitable for bearing, etc.), and the safety level of the components is divided into four levels: AU, BU, CU, and DU.
2. Safety appraisal of sub-unit (second floor): The safety appraisal of sub-unit is in accordance with the "Civil Building Reliability Appraisal Standard" GB 50292-2015, which is comprehensively considered and evaluated by the component set, and is divided into three parts: foundation foundation, upper load-bearing structure and enclosure structure. The safety level of the subunit is divided into four levels: AU, BU, CU, and DU.
3. Appraisal unit safety appraisal (three layers): The appraisal unit safety appraisal is based on the "Civil Building Reliability Appraisal Standard" GB 50292-2015, according to the foundation foundation, the upper load-bearing structure and the sub-units of the maintenance structure, as well as other factors affecting the safety of the structure for comprehensive assessment. The grading of the identification unit is divided into four levels: ASU, BSU, CSU and DSU.
03. The specific content of the safety appraisal of masonry structure.
Data investigation: consult the technical data such as the building's relevant architectural and structural construction drawings.
Investigation and testing of the current situation of the structure
Structural status inspection, including: use history investigation, structural function investigation, structural layout investigation, load distribution investigation, component damage investigation, structural connection investigation.
Identification and analysis: According to the on-site survey data and the current relevant standards and specifications, the bearing capacity, structure, deformation and crack damage of the building component level are identified and analyzed, the safety level of each component is evaluated, and the safety level of the structure is comprehensively analyzed and evaluated.
Appraisal conclusions. According to the appraisal and analysis, the safety appraisal conclusion of the house shall be issued, and the corresponding treatment opinions and suggestions shall be put forward according to the conclusion.
04. Conclusion.
The safety appraisal of masonry structure is based on the structural characteristics of masonry itself, comprehensively considering various influencing factors, and conducting a multi-faceted safety assessment of the building from local to whole, from micro to macro.
In the future, with the extension of the use time of existing masonry buildings, the safety problems of some building structures will be widespread, Intai Testing provides owners with one-stop solutions such as building testing and identification, reinforcement material comparison and selection, reinforcement design and construction, integrates excellent resources in the industrial chain, and is committed to a high degree of integration of resources to solve building safety problems for you!