3.3　Loads and Load Combinations

3.3.1　Categorization of loads applied on tank foundation shall comply with the following requirements:

1　Permanent loads:self-weight of tank（including the self-weights of insulation and attachments），foundation self-weight，and weight of soil on foundation，etc.

2　Variable loads:weight of liquid stored in tank or weight of water filled into tank for hydrostatic test，and wind load.

3.3.2　For design of tank foundation，the most unfavorable combination of load effects and its corresponding resistance limit shall comply with the following requirements：

1　When the bearing capacity of subgrade is checked or the number of piles is determined based on the bearing capacity of single pile，the nominal load combination in serviceability limit state shall be used to calculate the load effect transferred to the bottom of foundation or pile cap，and the corresponding resistance shall be the characteristic value of the bearing capacity of subgrade or the characteristic value of the bearing capacity of single pile.

2　When the subgrade deformation is calculated，the quasi-permanent combination in serviceability limit state shall be used to calculate the load effect transferred to the bottom of foundation，wind load and earthquake action shall not be included，and the corresponding limit shall be the allowable limit of tank subgrade deformation.

3　When the foundation stability is calculated，the fundamental combination in Ultimate limit states shall be used to calculate the load effect，but their partial coefficients shall be all taken as 1.0.

4　When the hoop tension of foundation ringwall and internal force of pile cap are calculated，and rebars is determined and material strength is checked，the fundamental combination in Ultimate limit states shall be used to calculate the combined load effects transferred to the foundation from upper structure，and corresponding partial coefficients shall be used.When the width of foundation crack is needed to be checked，nominal load combination in the serviceability limit state shall be used for calculation.

3.3.3　The partial coefficients of permanent loads in fundamental combination shall comply with the following requirements:

1　For self-weight of tank（including the self-weights of insulation and attachments）:1.2.

2　For the combined self-weight of foundation and weight of soil on the foundation:1.2.

3.3.4　The partial coefficients of variable loads in fundamental combination shall comply with the following requirements:

1　For the weight of hydrostatic test water:1.1.

2　For the weight of liquid:1.3.

3　The wind load applied onto the tank shall conform to the current national standard GB 50009:Load Code for the Design of Building Structures.

3.3.5　The coefficients of quasi-permanent combination shall comply with the following requirements:

1　For the weight of water filled into tank for hydrostatic test:0.85.

2　For the weight of liquid in tank:1.0.