Last night, a magnitude 7.4 earthquake struck off the eastern coast of Fukushima, Japan, with a focal depth of 57 kilometers and triggered a tsunami warning, with waves expected to be 1 meter high.
The earthquake was felt in much of eastern Japan, including Tokyo, while the quake cut off power to more than 2 million homes in the Tokyo area.
The earthquake caused damage in many parts of Japan, and in Fukushima Prefecture and other places, the road surface cracked and twisted, the window glass of buildings was broken, and road traffic was temporarily closed in some areas. In addition, the earthquake temporarily disrupted rail and subway traffic in Fukushima, Miyagi, and Tokyo.
In an interview with reporters, some people said that this may be the worst earthquake since she went to Japan in 2015, "at that time, the earthquake was very fierce, and the furniture at home was shaking." However, she also pointed out that Japanese apartments are very well protected from earthquakes, so it is safest to stay at home in the event of an earthquake.
It is true that because earthquakes often occur in Japan, the seismic performance of Japanese houses has been done very well, but what about the seismic performance of domestic houses? You know, earthquakes often occur in many parts of the continent, and once an earthquake occurs, is your house safe?
Next, we sorted out some relevant knowledge of housing earthquake resistance for your reference.
What structure house is more earthquake resistant?
The building structures of the houses with seismic resistance levels from high to low are, in order: steel structure> shear wall structure> frame structure> brick-concrete structure.
(1) Steel structure
Steel structure is to steel as the main structural material, which is characterized by high strength, light weight, and because steel has homogeneity and toughness, so the steel structure can produce greater deformation, can well withstand the power load, so as to have a strong seismic ability.
However, due to the relatively high construction cost of steel structures, the current application is not very common. Generally speaking, super high-rise buildings over 100 meters or buildings with large spans will use steel structures.
(2) Shear wall structure
Shear wall is the use of reinforced concrete wall panels to withstand the internal forces caused by various loads, and can effectively control the horizontal force of the structure, this kind of shear wall to withstand vertical and horizontal force structure is called shear wall structure.
At present, shear wall structures are widely used in high-rise housing buildings of 10 storeys and above or in buildings with a height of more than 24 meters.
(3) Frame structure
Frame structures are the most widely used in modern architecture, and most of the buildings we see are frame structures.
The frame structure is composed of load-bearing beams and columns poured with reinforced concrete, and then assembled by hollow bricks or prefabricated aerated concrete, ceramic particles and other lightweight plates as partition walls. The wall mainly plays a role in enclosure and isolation, so the wall is generally not load-bearing and can be made of various lightweight materials.
(4) Brick-concrete structure
The "brick" in the brick-concrete structure refers to a unified-size building material, including other sizes of special-shaped clay bricks, hollow bricks, etc.; "mixed" refers to the reinforced concrete ingredients prepared by steel, cement, sand and stone, and water in a certain proportion, including floor slabs, vials, stairs, balconies. Load-bearing walls made of brick are combined with these fittings, hence the name brick-concrete structure.
Under normal circumstances, most of the houses with a height of less than 24 meters or less than 10 floors use brick-concrete structures, and their seismic performance is relatively weak compared with the above three. At present, brick-concrete structures are rarely used in urban construction, and can only be seen in some suburban buildings.
In addition, in addition to the above four types of building structures, some buildings will use frame shear structures, that is, the combination of frame structures and shear wall structures. The architecture of this structure combines the advantages of the two structures, which can provide a large use space for the building layout and has good resistance, so the housing of this structure has good seismic resistance.
How to choose a earthquake-resistant house when buying a house?
Earlier, the state has stipulated the seismic level of the house, and the grade determines that the building structure should be divided into four seismic fortification categories of A, B, C and D according to the importance of its use function. The specific classification of building seismic fortification categories can be found in the provisions of the national standard "Classification Standard for Building Seismic Fortification" GB 50223.
At the same time, on December 31 last year, the Ministry of Housing and Urban-Rural Development issued the "Classification Standard for Seismic Fortification of Construction Projects" (Draft Articles for Partial Revision)", which clarified that secondary schools include secondary vocational schools, and supplemented the classification of fortifications for school buildings in special education schools, requiring that their seismic fortification categories should not be lower than the key fortification categories.
It can be seen that it is very important to stipulate the seismic level of the house, and the personal safety of the residents is more secure. Generally, in the process of buying a house, the developer will provide a house earthquake safety performance evaluation report issued by the seismic assessment agency. So, in addition to reading the report, what aspects can buyers choose from when buying a house?
(1) Look at building materials
As we have already said about the seismic resistance of various types of building structures, when buying a house, you can combine the above knowledge to pay attention to the building structure first, and then choose those building materials with ductility, because ductile materials have better seismic performance than brittle materials. In addition, there is a look at whether the walls of the house are solid, whether there are large cracks, drums or serious alkali erosion.
(2) Look at the type of apartment
In the layout of the building, according to the floor plan, it can be seen whether the vertical and horizontal wall load-bearing layout, or the horizontal wall load-bearing layout, or the vertical wall load-bearing layout. In general, the seismic performance of the longitudinal wall load-bearing layout or the horizontal wall load-bearing layout is better than that of the vertical wall load-bearing layout.
The source of the picture is an anchor
(3) Look at the environment of the house
It is necessary to see whether the terrain and landform of the surrounding environment of the house are safe, and whether the house is in a lot where landslides, subsidence, collapse or unstable ditches may occur. In general, mountain packs, steep rocks, gullies and ancient river channels are more susceptible to earthquakes.
(4) Remember not to easily change the original structure of the house when renovating
Some ground-floor residents will remove the load-bearing wall of the house in a large area without concealing the property during renovation, which is very dangerous. Because this will lead to the building's seismic performance weakened and the load stress abnormal, once an earthquake occurs, then the building may collapse at any time. Therefore, buyers must not easily change the original structure of the house when renovating. In addition, when choosing decoration materials, buyers should also pay attention not to be too heavy, otherwise it will increase the load on the floor slab, thereby reducing the seismic performance of the building.
Previously, experts suggested that the mainland is a country with frequent earthquakes, and the seismic performance of the house is related to the safety of the lives and properties of the majority of people, and the seismic resilience of the house should be further improved, the earthquake loss should be reduced, and the normal operation of the society should be quickly restored after the earthquake. It can be seen that it is urgent to further improve the seismic toughness of housing.
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