Dangerous building appraisal standards, appraisal processes and methods! These six points must be noted.

Nowadays, real estate developers are constantly building new houses, and many old houses are in danger. Dangerous houses are not allowed to live in, and they are houses with potential safety hazards. The relevant laws of our country have such a clear definition of dangerous houses, and there are a series of definition standards. Once this standard is reached, the house is dangerous. So what are the procedures for the appraisal standard of dangerous houses? Nowadays, real estate developers are constantly building new houses, and many old houses are in danger. Dangerous houses are not allowed to live in, and they are houses with potential safety hazards. The relevant laws of our country have such a clear definition of dangerous houses, and there are a series of definition standards. Once this standard is reached, the house is dangerous. So what are the procedures for the appraisal standard of dangerous houses?

A, dangerous appraisal standards

1. This standard is formulated to ensure the safety of residence and provide a basis for the identification of dangerous houses.

2. This standard is applicable to the houses managed by the real estate management department. The valuation of all units and private houses can refer to this standard. This standard does not apply to industrial buildings, public buildings, high-rise buildings and cultural relics protection buildings.

3. The components mentioned in this standard refer to load-bearing components; The structure mentioned refers to a system composed of load-bearing members.

4. For important houses or complex structures that are difficult to identify, necessary tests and calculations should be carried out.

5. When the factors that constitute dangerous houses vary greatly from place to place, the local real estate management department may formulate detailed rules or supplementary provisions when implementing this standard.

Second, the dangerous ingredients

Dangerous component refers to the deformation that the component has reached the limit state of its bearing capacity and is not suitable for further bearing.

Third, the assembly unit.

(1) Foundation

1, independent column foundation is based on a single foundation of a column;

2. The strip foundation is based on the unilateral length of the natural room;

The whole house is calculated according to the area of natural room.

4. The wall is one story high, and one side of the natural room is a unit;

5, column with a layer of a unit;

6, beams, joists, purlins, etc. Take one span as a unit.

7. Prefabricated boards are in blocks, and rammed boards are in the area of natural rooms;

8. The roof truss is a truss.

(2) Foundation and foundation

1. Uneven settlement caused by geological sliding, serious insufficient bearing capacity, or other special geological reasons causes obvious inclination, displacement, cracks and distortion of the structure, and it has a trend of continuous development.

2. Ground-based buildings increase the load, or increase the load due to local storey addition, or cause uneven settlement due to other human factors, resulting in obvious inclination, displacement, cracks and distortion of the structure, and there is a trend of continuous development.

3. The aging, corrosion, brittleness and fracture of the foundation lead to obvious inclination, displacement, cracks and distortion of the structure.

Four, reinforced concrete structural members

(1) Columns and walls

1, column crack, protective layer peeling, main reinforcement exposed; Or there are obvious horizontal cracks on one side, and the concrete on the other side is crushed to expose the main reinforcement; Or produce obvious cross cracks.

2. There are obvious cross cracks in the middle of the wall, or the protective layer falls off.

3. The column and wall are inclined, and the inclination exceeds1100 of the height.

4, column, wall concrete brittle cracking, carbonation, bulging, failure surface more than 0/3 of the total area, and the main reinforcement exposed, serious corrosion, cross section reduction.

② Beam and plate

1, single beam, continuous beam midspan, transverse cracks at the bottom, and one side of the cracks extends upward to more than 2/3 of the beam height; Or there are many obvious horizontal cracks on it, the upper protective layer falls off and the bottom is accompanied by vertical cracks; Or the continuous beam produces obvious vertical cracks near the support; Or produce obvious horizontal cracks or oblique cracks between the bearing and the concentrated load part.

2. The frame beam has obvious vertical cracks or oblique cracks or cross cracks at the fixed end.

3. Obvious oblique cracks are produced at the ends of simply supported beams and continuous beams, and obvious vertical cracks or oblique cracks are produced at the roots of cantilever beams.

4. Cracks appear on the periphery of the rammer plate above, or cross cracks appear below.

5. There are obvious vertical cracks under the precast slab.

6. Deflection generated by various beams and plates exceeds the span1150, and the crack width in tension area is greater than1mm. ..

7, all kinds of plate protective layer peeling off, more than half of the main reinforcement exposed, serious corrosion, cross section is reduced.

9, prestressed precast slab vertical cracks; Or the end concrete is loose and bare, and the length exceeds 100 of the main reinforcement.

(3) Roof truss

1, the deflection exceeds the span1150, and the bottom chord crack is greater than 1mm vertical crack.

2. Failure of the supporting system leads to inclination, which exceeds 2/ 100 of the height of the roof truss.

3. The protective layer falls off, and the main reinforcement is exposed and corroded in many places.

4, the end node connection is loose, and there are obvious cracks.

(4) wall

1, vertical cracks with joint length exceeding 1/2 stories high and joint width exceeding 2 cm, or multiple vertical cracks with joint length exceeding 1/3 stories high.

2. There are obvious vertical cracks in the wall under the beam support.

3. There are obvious cross cracks, vertical cracks or horizontal cracks in the doors and windows or the walls between windows.

4. Tilting occurs, and the tilting amount exceeds1.5100 of the story height (more than three stories, exceeding 0.7/ 100 of the total height), or the joint of adjacent walls is broken.

5. Weathering, peeling, and mortar pulverization cause the wall and effective section to weaken by more than 1/4 (the average value exceeds 1/3).

⑤ column

1, horizontal cracks appear in the column body, or vertical through cracks appear, and the joint length exceeds 1/2 of the column height.

2. There are many vertical cracks in the column under the beam support.

3. Tilting occurs, and the tilting amount exceeds 1.2/ 100 of the story height (more than three stories, exceeding 0.5/ 100 of the total height).

4. Weathering, fragmentation and mortar pulverization have reduced the effective cross-section by more than 65,438+0/5 (single-story houses are more than 65,438+0/4).

[6] lintels and arches

1, obvious vertical cracks appear in the middle of lintel; Or obvious oblique cracks are produced at the end; Or the wall supporting the lintel produces horizontal cracks; Or produce obvious bending and sinking deformation.

2, pipe arch, flat shell, corrugated pipe arch, vault bus cracks; Or the arch of the foot is obviously deformed; Or the arch and foot are obviously displaced; Or the arch tie rod is loose, or the corrosion is serious, and the section is reduced.

Verb recognition (abbreviation for verb)

(1) Dangerous buildings (referred to as dangerous buildings for short) refer to houses with dangerous load-bearing components, unstable structures and bearing capacity, which may collapse at any time and cannot guarantee the safety of living.

(two) dangerous houses are divided into whole houses and local dangerous houses:

1, the whole dangerous building refers to the house that may collapse at any time;

2. Local dangerous houses refer to houses that may collapse at any time.

(three) the identification of dangerous houses is based on houses, and the construction area is measured in square meters.

1, the whole dangerous building is measured in square meters with the construction area of the whole building;

2, local dangerous buildings to endanger the collapse of the building area of more than square meters.

(four) the identification of dangerous buildings should be based on the risk identification of foundation and structural components, combined with historical status and development trend, comprehensive analysis and comprehensive judgment.

(5) When judging the danger of foundation or structural members, whether the danger of members is isolated or related should be considered.

1, if the hazard of the component is isolated, it does not constitute a structural hazard;

2. If the hazards of components are related, the scope of hazards should be determined by contact structure.

(6) In terms of historical position and development trend, the following factors should be considered on the foundation: the influence of structural members on danger.

1, structural aging degree;

2, the influence of the surrounding environment;

3. The value of design safety;

4. Human factors that destroy the structure;

5. Dangerous development trend.

Six, the risk classification

Grade A: the bearing capacity of the structure can meet the requirements of normal use, there is no danger point of decay, and the building structure is safe.

Grade B: The bearing capacity of the structure basically meets the requirements of normal use, and individual structural members are in a dangerous state, but it does not affect the main structure and basically meets the requirements of normal use.

Grade C: The bearing capacity of some load-bearing structures can not meet the requirements of normal use, resulting in local danger, which constitutes a local dangerous building.

Grade D: The bearing capacity of the load-bearing structure can no longer meet the requirements of normal use, and the whole house is in danger, which constitutes a whole dangerous house.

The above are some standards for the identification of dangerous houses, which I believe everyone knows. In this regard, we can also know that there are grades of dangerous houses. It can be divided into four grades: A, B, C and D. The higher the grade, the higher the risk index. Chinese government departments will make corresponding renovation or compensation for dangerous houses according to different grades.