Code for Design of Prestressed Concrete Structures English
1 General Provisions
1.0.1 This code is formulated with a view to implementing the technical and economic policies of the nation during the design of prestressed concrete structure, and thus achieving safety and applicability, advanced technology, economic rationality and guaranteed quality.
1.0.2 This code is applicable to the design of prestressed concrete structure for housing and general structures.
1.0.3 In addition to this code, the design of prestressed concrete structure shall also meet the requirements of the current relevant standards of the nation.
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2 Terms and Symbols
2.1 Terms
2.1.1 prestressed concrete structure
concrete structure for which stressed tendon is configured and prestress is set up by tensioning or other ways
2.1.2 pretensioned prestressed concrete structure
concrete structure of which prestress is set up by setting tensioned tendons and bonding them for transmitting after tensioning the tendon on pedestal and pouring concrete
2.1.3 post-tensioned prestressed concrete structure
concrete structure of which prestress is set up by tensioning the tendon and anchoring structurally after concrete reaches specified strength
2.1.4 unbonded prestressed concrete structure
post-tensioned prestressed concrete structure configured with unbonded tendon that can keep relative sliding with concrete
2.1.5 externally prestressed structure
structure for which post-tensioned tendon is configured outside the section of concrete member
2.1.6 prestressed steel reinforced concrete structure
structure for which rolling or welding forming profile steel is configured in the prestressed concrete structure
2.1.7 tendon
a generic term for the steel wire, steel strand, prestressed screw-thread steel bar and FRP tendon used for applying prestress in concrete structure member
2.1.8 epoxy-coated prestressing steel strand
prestressed steel strand whose external layer is coated by fusion bonded epoxy coating and space between steel wires is filled with fusion bonded epoxy coating for preventing the invasion of corrosive medium via capillary force or the invasion of other hydrostatic force
2.1.9 FRP tendon
fiber reinforced polymers composed of multistrand continuous aramid fiber polymer materials or carbon fiber polymer via gluing with substrate materials such as polyamide resin, polyethylene resin or epoxy resin and squeezing and draw forming with special mould
2.1.10 unbonded tendon
a kind of tendon that is unbonded with surrounding concrete and transmits pressure to member or structure via anchorage after its surface is coated with anti-corrosive grease and it is wrapped with sheath
2.1.11 bonded tendon
a kind of tendon that is bonded with concrete or bonding with concrete through grouting after it is tensioned
2.1.12 retard-bonded prestressing steel strand
prestressing steel strand that is coated and wrapped with retarding adhesive and high density polyethylene sheath
2.1.13 external tendon
tendon arranged outside the structural member section and transmitting prestress to structure via the anchor end block and deviator connected with structural member
2.1.14 anchorage
permanent anchor device, used for keeping the tension of tendon and transmitting it to member or structure, in post-tensioned prestressed member
2.1.15 coupler
device for connecting tendons
2.1.16 anchorage zone
zone for some members that bears the pre-applied force from anchorage and makes the stress on concrete section tend to uniform
2.1.17 deviator
concrete or steel bearing block arranged at web plate, flange or the joint of web plate and flange
2.1.18 control stress for tensioning
stress applied at the tensioning end when tensioning the tendon
2.1.19 prestressing loss
the stress drop of tendon induced by factors such as material characteristics, structural state and tensioning technology during and after the tensioning of tendon
2.1.20 effective prestress
stress maintained in tendon after the completion of prestressing loss
2.1.21 primary internal force
internal force generated by pre-applied force on the section centroid of unrestrained prestressed member
2.1.22 resultant internal force
internal force generated by pre-applied force on member section of post-tensioned statically indeterminate prestressed structure
2.1.23 secondary internal force
additional internal force induced by pre-applied force on post-tensioned statically indeterminate prestressed structure at excess constraint area
2.2 Symbols
2.2.1 Material characteristics,
C30——the strength grade of concrete with standard value of cube compressive strength of 30N/mm2;
Ea——the elastic modulus of profile steel;
Ec——the elastic modulus of concrete;
——the fatigue deformation modulus of concrete;
Ep——the elastic modulus of tendon;
Es——the elastic modulus of steel bar;
fa, f′a——the design value of tensile and compressive strength of profile steel;
fak, f′ak——the standard value of tensile and compressive strength of profile steel;
fck, fc——the standard value and design value of axial compressive strength of concrete;
f′ck, f′tk——the standard value of axial compressive strength and axial tensile strength of concrete at construction stage;
f′cu——the compressive strength of concrete cube with side length of 150mm under maintenance at same site condition at construction stage;
ffpc——the design value of persistent strength of FRP tendon;
fpy, f′py——the design value of tensile and compressive strength of tendon;
fstk, fptk——the standard value of ultimate strength of ordinary steel bar and tendon;
ftk, ft——the standard value and design value of axial tensile strength of concrete;
fy, f′y——the design value of tensile and compressive strength of ordinary steel bar;
fyk, fpyk——the standard value of yield strength of ordinary steel bar and tendon.
2.2.2 Action and effect
Fl——the design value of local load or the design value of concentrated counterforce;
M——the design value of bending moment;
M2——the secondary bending moment generated by pre-applied force on statically indeterminate structure of post-tensioned prestress concrete;
Mk, Mq——the bending moment calculated according to standard combination and quasi-permanent combination of loads effect;
Mu——the design value of bending capacity of member normal section;
Mcr——the cracking bending moment of normal section of flexural member;
N——the design value of axial force;
N2——the secondary axial force generated by pre-applied force on the statically indeterminate structure of post-tensioned prestress concrete;
Nk, Nq——the axial force calculated according to standard combination and quasi-permanent combination of loads effect;
Np——the resultant force of post-tensioned member tendon and ordinary steel bar;
Np0——the resultant force of tendon and ordinary steel bar when the normal prestress of concrete is equal to zero;
Nu0——the design value of axial compressive or axial tensile capacity of member section;
Nux, Nuy——the design value of eccentric compressive or eccentric tensile capacity of axial force acting on x-axis and y-axis;
T——the design value of torque;
V——the design value of shear force;
V2——the secondary shear force generated by pre-applied force on the statically indeterminate structure of post-tensioned prestress concrete;
Vcs——the design value of shear capacity of concrete and stirrup on member oblique section;
σcon——the control stress for tensioning of tendon;
1 General Provisions
2 Terms and Symbols
2.1 Terms
2.2 Symbols
3 Materials
3.1 Concrete and Tendon
3.2 Fiber Reinforced Polymer Bars
3.3 Anchorage and Coupler for Tendon
3.4 Pore Canal and Grouting Material
4 Basic Requirements
4.1 General Requirements
4.2 Analysis on Internal Force
4.3 Calculation of Prestressing loss
4.4 Checking at Construction Stage
4.5 Seismic Design
4.6 Durability Requirements
5 Calculation of Ultimate Limit States
5.1 General Requirements
5.2 Calculation of Flexural Capacity of Normal Section
5.3 Calculation of Tension Capacity of Normal Section
5.4 Calculation of Compression Capacity of Normal Section
5.5 Calculation of Oblique Section Bearing Capacity
5.6 Calculation of Oblique Section Bearing Capacity
5.7 Calculation for Punching Bearing Capacity
5.8 Calculation of Local Compression Capacity and Design of Anchorage Zone
5.9 Checking of Fatigue
6 Checking of Serviceability Limit States
6.1 Checking of Stress
6.2 Checking of Deflection of Flexural Members
6.3 Checking of Crack Control
7 Prestressing Design of Super Long Structure
7.1 General Requirements
7.2 Calculation Analysis
7.3 Principles for Design
7.4 Constructional Measures and Construction Requirement
8 Design of Prestressed Steel Reinforced Concrete and Steel-Concrete Composite Beams
8.1 General Requirements
8.2 Calculation of Ultimate Limit States
8.3 Checking of Cracks
8.4 Checking of Deflection
9 Design of External Prestressed Reinforced Concrete Structure
9.1 General Requirements
9.2 Ultimate Limit States Design
9.3 Checking of Serviceability Limit States
9.4 Detailing Requirements
10 Design of FRP Prestressed Reinforced Concrete Structure
10.1 General Requirements
10.2 Loss of Prestress
10.3 Ultimate Limit States Design
10.4 Checking of Serviceability Limit States
10.5 Detailing Requirements
11 Detailing Requirements
11.1 General Requirements
11.2 Pretensioned Members
11.3 Post-tensioned Members
Annex A Secondary Internal Force Calculation of Concrete Frame With Several Frequently Used Prestressing Arrangements
Annex B Commonly Used Linear Arrangement of External Prestressing and Secondary Internal Forces Calculation
Explanation of Wording in This Code
List of Quoted Standards
