3 Basic Requirements

3.1 Classification and Representative Value of Loads

3.1.1　Loads involved in this code refer to their characteristic values.The characteristic values of loads shall be determined according to relevant requirements in this code.

3.1.2　Loads acting on building structures can be classified into three types:

1　Permanent loads:including self-weight of structures，soil pressure，prestress，etc.

2　Variable loads:including live loads on floor（ground）and roof，loads of equipment（piping），dust loads，crane loads，wind loads，snow loads and thermal action，etc.

3　Accidental loads:including loads due to explosive force，short circuit moment，impact force，loads due to postulated pipe rupture，tornado loads，etc.

3.1.3　Under normal operating conditions of units，loads due to self-weight of equipment（piping），weight of materials filled in equipment（piping）and vessels，dynamic loads of equipment（piping），tension of coal convey or and conductor tension may be considered as variable loads under normal operating conditions.

Under abnormal operating conditions of units，loads due to accidental accumulation of pulverized coal（ash）in equipment（piping），hydraulic test，steam exhausting and short-circuit current of common electrical equipment shall be considered as variable loads under abnormal operating conditions.

3.1.4　Accidental explosion load of pulverized coal bunker，vented explosion load of explosion vents on equipment（piping），transient force caused by sudden change of fluid flow momentum in piping，postulated pipe rupture load，short-circuit current load of the turbine-generator，and tornado loads shall be considered as accidental loads.

3.1.5　In design of building structures，representative values of different loads shall be determined according to the current industrial standard Technical Code for the Design of Civil Structure of Fossil-fired Power Plant DL 5022.

3.1.6　In the design of ultimate limit states or serviceability limit states according to the characteristic combination，for variable load，the combination value or characteristic value shall be its representative value according to the specified load combination.

The combination value of a variable load shall be the product of the characteristic value and the coefficient for combination value of the load.

3.1.7　In the design of serviceability limit state according to frequent combination，for variable load，the frequent value or quasipermanent value shall be its representative value；in the design according to quasi-permanent combination，the quasi-permanent value of variable load shall be its representative value.

The frequent value of a variable load shall be the product of the characteristic value and the coefficient for frequent value of the load.

The quasi-permanent value of a variable load shall be the product of the characteristic value and the coefficient for quasipermanent value of the load.

3.1.8　The adjustment factor for variable loads to account for different design working life shall be determined according to the relevant provisions in current national standards Load Code for the Design of Building Structures GB 50009 and Unified Standard for Reliability Design of Engineering Structures GB 50153.