by ▲ click the blue character above to pay attention to PKPM construction technology! With China’s economic development, the functions of public and civil buildings are more diversified, and the demand for housing reconstruction is increasing day by day; At the same time, the years have left irresistible traces on the old houses.
In the comprehensive renovation project of the old community, the safety and usability of the houses are livelihood projects related to the happiness of the people.
Based on the principles of renewable resources, energy conservation and environmental protection, the management system of relevant housing safety specifications, the functional change, capacity expansion and seismic fortification level requirements of new and old buildings, the old houses that reach the design service life, and the disaster damage of houses, all involve the identification, reinforcement or transformation of building structures.
In the identification or reinforcement of existing structures, the bearing capacity is one of the important indicators to determine the safety of load-bearing members.
For the evaluation of the bearing capacity of existing members or complex member sections strengthened by various methods, the current code calculation methods have certain limitations.
Combined with the design code, this paper uses PKPM complex section design software gsec to model the strengthened members, Through its bearing capacity analysis and reinforcement design functions, the member reinforcement design is carried out, and the three-dimensional bearing capacity of the section is evaluated, and the member reinforcement design based on nonlinear analysis method is realized.
Application process of lgsec in identifying reinforced member design PKPM general reinforced concrete section nonlinear bearing capacity analysis and reinforcement software gsec is a tool for bearing capacity analysis and reinforcement design of any complex section, It has the following capabilities: 1) bearing capacity analysis of reinforced concrete members with arbitrary shape section (including common sections such as composite wall, steel reinforced concrete and rectangular circle); 2) reinforcement design of reinforced concrete members with arbitrary shape section; 3) calculation of three-dimensional bearing capacity envelope ball.
The above functions just provide a reliable safety evaluation method for irregular sections after reinforcement.
In fact, pkpm-satwe needs to be combined when identifying the section design and bearing capacity checking calculation of reinforced members According to the calculation, the actual stress of the member in the structure is obtained.
Finally, the bearing capacity analysis of gsec and the three-dimensional bearing capacity envelope ball are used to evaluate the safety of the member.
The general process is shown in Figure 1.
Figure 1 ● calculation application example of component design and checking flow chart ● checking the bearing capacity of column wrapped steel method.
The change of the use function of a project involves the addition of equipment and the change of service load.
Therefore, the comprehensive safety appraisal of the structure is carried out according to the requirements.
The appraisal conclusion is that the bearing capacity of some components does not meet the requirements, so reinforcement is recommended.
As shown in Figure 2, the reinforcement of a column does not meet the requirements, so it is proposed to use the outsourcing steel method for reinforcement.
Figure 2.
Pkpm-jdjg reinforcement model with wrapped steel method generally speaking, the original structure is calculated by using PKPM’s jdjg identification reinforcement software to obtain the difference between the calculated reinforcement and the actual reinforcement.
At this time, the reinforced section of wrapped steel is estimated according to the equivalent reinforcement area.
Set the estimated reinforcement section in jdjg software (Fig.
3) and calculate it in the member information calculation sheet (Figure 4) check whether the cross-sectional area of the newly added section steel meets the requirements.
Figure 3 ， section parameters of pkpm-jdjg outsourcing steel method Figure 4 ， calculation sheet of pkpm-jdjg reinforcement design component.
This method is commonly used at present, and the reinforcement and calculation methods are based on the specifications.
We can think that the components strengthened by this method meet the requirements of the specifications and bearing capacity.
However, the actual strength of the components after reinforcement What is the international carrying capacity and how much security and affluence it has, but there is no place to know.
Based on gsec software, section modeling and bearing capacity analysis can be realized, and the bearing capacity of members can be directly understood through the bearing capacity envelope ball.
The implementation process of bearing capacity calculation of reinforced members using gsec software is introduced below.
Input the original reinforcement and internal force of the column section into gsec software, and arrange the additional section steel on the member.
The general information of the section is shown in Table 1, and the information of the original section and the reinforced section in gsec is shown in Figure 5.
Fig.
5.
The original section and the reinforced section model in gsec.
It should be noted here that in accordance with article 11.1.6 of code for design of concrete structures (gb50010-2010) (hereinafter referred to as the code for concrete), when considering the seismic action combination to check the bearing capacity of concrete structural members, the seismic adjustment coefficient of bearing capacity shall be used γ Re adjustment.
Therefore, the “load amplification factor” in gsec software can be used to realize the seismic adjustment of bearing capacity.
Such as eccentric compression column with axial compression ratio ≥ 0.15 γ Re is taken as 0.8, and the “load amplification factor” is filled as 0.8.
Reducing the load effect is equivalent to amplifying the resistance.
Through calculation, it is concluded that the bearing capacity of the members after steel clad reinforcement meets the requirements, and the calculation results of bearing capacity are shown in Table 2.
From the calculated bearing capacity envelope ball (Fig.
6), it can be seen visually that the bearing limit N-M of the member is -460.88kn (taken as -576.71 × 0.8), draw M-M curve, as shown in Figure 7.
The actual bending moment of the member is within the envelope, which proves that the bearing capacity of the strengthened member is sufficient.
thus, The checking calculation process of bearing capacity of reinforced members in this example can be summarized (Fig.
8).
Fig.
6 ， envelope sphere of component bearing capacity Fig.
7 ， M-M curve of component axial force Fig.
8 ， checking calculation process of component reinforcement bearing capacity ● checking calculation of bearing capacity of wall limb thickening complex section after identification, it is found that the displacement index slightly does not meet the requirements.
It is proposed to reduce the structural displacement by increasing the thickness of shear wall and improving the structural stiffness, and ensure that the bearing capacity of structural components meets the requirements Please.
However, the existing software is not perfect for the calculation of the bearing capacity of the thickened shear wall.
At this time, gsec software can be used to calculate the actual bearing capacity of the sections of the old and new reinforced concrete composite walls.
The approximate process is shown in Figure 9..
