Treatment of masonry structure wall under the acti

  • Detail

Through the analysis of the bearing capacity of the wall under the combined action of wind load and vertical load, this paper deduces the wall arrangement relationship that the masonry structure meets the safety requirements, and calculates the ratio of the Bay, height and depth between the solid wall and the empty bucket wall under the conditions of the change of masonry strength, wind load and wall height thickness ratio, The structural requirements and measures for strengthening the wall connection are put forward

1. Overview

masonry structure has been widely used in rural housing construction in China, as well as in coastal areas, because of its wide range of building materials, simple and convenient construction, low cost and other characteristics; However, the masonry structure also has many defects: the bearing capacity of the masonry structure is low, the integrity is poor, and the ability to resist horizontal load is weak. Therefore, the masonry structure in the coastal areas affected by strong typhoons has suffered serious damage or collapse due to excessive wind pressure. For example, on August 8, 2004, the strong typhoon "Yunna" made landfall in Taizhou City, Zhejiang Province, causing 11326 civilian houses to collapse, including more than 6000 masonry and brick wood structures. On August 10, 2006, the super typhoon "Sangmei" landed in Cangnan County, Wenzhou City, Zhejiang Province, causing more than 16200 houses to collapse

in masonry structure, vertical and horizontal walls are one of the most important load-bearing components, which transmit the vertical and horizontal loads on the structure to the foundation. Therefore, the level of wall bearing capacity determines the safety of masonry buildings. Because the bearing capacity of the wall is related to many factors, such as the height thickness ratio of the wall, the compressive, shear and bending strength of the masonry, the layout of the wall and the type of load

in practical projects, some owners blindly pursue the wall layout form with large bays and high-rise, which has an adverse impact on the structural safety (to ensure the comfort of housing), and this wall layout form is very easy to cause the wall to collapse under the action of horizontal load; In order to not only ensure the comfort of housing, but also ensure the safety of the structure, it is necessary to determine a reasonable wall layout by analyzing the relationship between the stress conditions of the wall and the bearing capacity of the wall

II. Load distribution and failure type of the wall

the following takes the two-story masonry structure which is the most common in the coastal area of Zhejiang Province as an example, and carries out the stress analysis and bearing capacity checking calculation of the wall according to the relevant national specifications

when the masonry structure is under the action of strong typhoon, the walls around the structure are subjected to the combined action of vertical and horizontal loads. Under such stress conditions, there may be three failure types of the wall: a) eccentric compression failure of the wall under the combined action of vertical pressure and horizontal thrust; b) Under the action of horizontal thrust, the wall will produce toothed bending failure along the middle of the wall; c) Under the combined action of vertical pressure and horizontal thrust, the wall will produce shear failure

III. relationship between wall bearing capacity and wall layout

in general village and town housing construction projects, the wall thickness is 240mm, and prefabricated hollow floors are mostly used for floors. According to the relevant provisions of the load code for building structures, the design load of the floor can be taken as 5.8kn; The design load of the roof can be taken as 5.7kn The design value of volume weight of solid wall (painted on both sides) with materials from the same material group is taken as 6.8kn/m2; The design value of the volume weight of the empty bucket wall (painted on both sides) is taken as 4.4kn/m2

the reasons why the relevant parameters of masonry strength are not taken according to the new code (GB) are: a) the strength grade of mortar in rural housing buildings is generally low and discrete, so it is difficult to reach the lowest strength grade M2.5 in the new code (GB); b) At present, sintered ordinary clay bricks are widely used in village and town buildings. As the function of wall materials gradually changes from load-bearing to enclosure, the strength grade of sintered ordinary clay bricks is generally low; c) At present, most village and town houses are constructed by rural craftsmen, who have not received professional training, and their imports are decreasing; 2. Without much relevant knowledge, the randomness of construction is large, which is easy to cause a wide range of fluctuations in the construction quality of the wall and affect the bearing capacity of the wall

through calculation, it can be seen that in the areas affected by strong typhoons, empty bucket walls should not be used as load-bearing walls in rural housing buildings. For the houses with the highest protection grade of kn100 and kp100 and solid walls, the mortar strength grade should be M2.5 or above. At this time, the height thickness ratio of the wall can be about 18 (the wall height is about 4.2 ~ 4.5 meters), and the Bay size of the wall is 4.8 ~ 5.1 meters. Such a wall structure layout relationship can meet the requirements of general village and town houses

Copyright © 2011 JIN SHI