High-strength bolted connection structure with no fire protection

• US 20040050013A1
• Filed: 09/12/2003
• Published: 03/18/2004
• Est. Priority Date: 09/12/2002
• Status: Abandoned Application

• Current Assignee: Nippon Steel Corporation
• Original Assignee: Nippon Steel Corporation
• Inventors: Okada, Tadayoshi, Kubota, Shin, Uno, Nobuyoshi
• Application Number:
  US10/663,060
• Publication Number:
  US 20040050013A1
• Time in Patent Office: Days
• US Class Current: 52/726.2
• CPC Class Codes: E04B 1/2403 Connection details of the elongated load-supporting parts
• CPC Class Codes: E04B 2001/2415 Brackets, gussets, joining plates
• CPC Class Codes: E04B 2001/2418 Details of bolting
• CPC Class Codes: E04B 2001/2454 Connections between open and closed section profiles
• CPC Class Codes: E04B 2001/2457 Beam to beam connections
• CPC Class Codes: E04C 3/06 with substantially solid, i.e. unapertured, web E04C3/10, E04C3/11 take precedence honeycomb girders E04C3/083
• CPC Class Codes: E04C 3/32 of metal E04C3/36 takes precedence

Abstract

The present invention provides a high-strength bolted connection structure for realizing a steel structure with no fire protection, which is capable of adequately assuring high-temperature strength of the connection in a high temperature region of 650° C., and which does not depend on a fire protection or protective structure using fire resistant material, wherein ultra-high-strength bolts having excellent fire resistance and excellent resistance to delayed fracture are used, which bolt have a tensile strength at room temperature (TS) of 1200 N/mm² or higher, and satisfies the relation that the shear proof stress at high temperature of 650° C. (bτt) is not less than (coefficient of slip at room temperature (μ)×design bolt tension (N₀))/(safety factor for long term load (ν)×cross-sectional area of bolt shank (bAs)).

Claims

1. A high-strength bolted connection structure with no fire protection, the high-strength bolted connection structure having the fire resistance of a steel structure comprising columns and/or beams, characterized in that ultra-high-strength bolts having a bolt tensile strength (TS) at room temperature of 1200 N/mm² or higher and excellent fire resistance with a bolt shear proof stress (bτ

t) at 650°

C. satisfying the relation <

1>

below, are used;

bτ

t≧

μ

×

N₀/(ν

×

bAs)  

 

<

1>

where

bτ

t;

bolt shear proof stress at high temperature (N/mm²)

bτ

t=TSt/{square root}3

TSt;

tensile strength of the bolts at high temperature (N/mm²)

μ

;

coefficient of slip at room temperature

N₀;

design bolt tension (N)

ν

;

safety factor for long-term load

bAs;

cross-sectional area of bolt shank (mm²).

2. A high-strength bolted connection structure with no fire protection according to claim 1, wherein, in said high-strength bolted connection structure, the long term allowable shear force (Qs) of said beam at room temperature satisfies the relation <

2>

below;

Qs≦

{ns×

bτ

+(nf−

ns)×

bτ

t}×

bAs  

 

<

2>

where

Qs;

long term allowable shear force of the beam at room temperature (N)

Qs=fs×

Ab

fs;

long term allowable shear proof stress of the beam (N/mm²)

Ab;

cross-sectional area (mm²)

ns;

number of tension bolts in the floor slab on upper flange side of the beam

bτ

;

shear proof stress of bolt at room temperature (N/mm²)

bτ

=TS/{square root}3

TS;

tensile strength of bolt at room temperature (N/mm²)

nf;

number of tension bolts on the upper flange side of the beam

bτ

t;

shear proof stress of bolt at high temperature (N/mm²)

bτ

t=TSt/{square root}3

TSt;

tensile strength of bolt at high temperature (N/mm²)

bAs;

cross-sectional area of bolt shank (mm²).

3. A high-strength bolted connection structure with no fire protection according to claim 1 or 2, wherein said high-strength bolted connection structure is composed of sets of a high-strength bolt, a nut, and a washer, and joint metals, and wherein said nut and washer are a general structural hexagon nut and a structural high strength plain washer for which no fire resistance is provided.

4. A high-strength bolted connection structure with no fire protection according to claim 1 or 2, wherein said high-strength bolted connection structure is composed of sets of high strength bolt, a nut, and a washer, and joint metals, and wherein a part or all of said joint metals are formed of steel material having an assured high-temperature strength.

5. A high-strength bolted connection structure with no fire protection according to claim 1 or 2, wherein, in said high-strength bolted connection structure, a part or all of said columns and/or beams used are formed of steel material having an assured high temperature strength.

6. A high-strength bolted connection structure with no fire protection according to claim 1 or 2, wherein said high-strength bolt is a ultra-high-strength bolt which contains, in % by weight, C:

0.30˜

0.45%, Si;

less than 0.10%, Mn;

more than 0.40%˜

less than 1.00%, P;

less than 0.010%, S;

0.010% or less, Cr;

0.5% or more˜

less than 1.5%, Mo;

more than 0.35%˜

less than 1.5%, V;

more than 0.3%˜

1.0% or less, with the balance being Fe and unavoidable impurities, and which has excellent fire resistance and resistance to delayed fracture such that following relations <

3>

, <

4>

are satisfied;

TS≦

(1.1×

T+850)  

 

<

3>

TS≦

(550×

Ceq+1000)  

 

<

4>

where

TS;

tensile strength of the high strength bolt at room temperature (N/mm²)

T;

tempering temperature (°

C.)

Ceq;

carbon equivalent (%)

Ceq=C+(Mn/6)+(Si/24)+(Ni/40)+(Cr/5)+(Mo/4)+(V/14).

7. A high-strength bolted connection structure with no fire protection according to claim 3, wherein said high-strength bolt is an ultra-high-strength bolt which contains, in % by weight, C:

0.30˜

0.45%, Si;

less than 0.10%, Mn;

more than 0.40%˜

less than 1.00%, P;

less than 0.010%, S;

0.010% or less, Cr;

0.5% or more˜

less than 1.5%, Mo;

more than 0.35%˜

less than 1.5%, V;

more than 0.3%˜

1.0% or less, with the balance being Fe and unavoidable impurities, and which has excellent fire resistance and resistance to delayed fracture such that following relations <

3>

, <

4>

are satisfied;

TS≦

(1.1×

T+850)  

 

<

3>

TS≦

(550×

Ceq+1000)  

 

<

4>

where

TS;

tensile strength of the high strength bolt at room temperature (N/mm²)

T;

tempering temperature (°

C.)

Ceq;

carbon equivalent (%)

Ceq=C+(Mn/6)+(Si/24)+(Ni/40)+(Cr/5)+(Mo/4)+(V/14).

8. A high-strength bolted connection structure with no fire protection according to claim 4, wherein said high-strength bolt is an ultra-high-strength bolt which contains, in % by weight, C:

0.30˜

0.45%, Si;

less than 0.10%, Mn;

more than 0.40%˜

less than 1.00%, P;

less than 0.010%, S;

0.010% or less, Cr;

0.5% or more˜

less than 1.5%, Mo;

more than 0.35%˜

less than 1.5%, V;

more than 0.3%˜

1.0% or less, with the balance being Fe and unavoidable impurities, and which has excellent fire resistance and resistance to delayed fracture such that following relations <

3>

, <

4>

are satisfied;

TS≦

(1.1×

T+850)  

 

<

3>

TS≦

(550×

Ceq+1000)  

 

<

4>

where

TS;

tensile strength of the high strength bolt at room temperature (N/mm²)

T;

tempering temperature (°

C.)

Ceq;

carbon equivalent (%)

Ceq=C+(Mn/6)+(Si/24)+(Ni/40)+(Cr/5)+(Mo/4)+(V/14).

9. A high-strength bolted connection structure with no fire protection according to claim 5, wherein said high-strength bolt is an ultra-high-strength bolt which contains, in % by weight, C:

0.30˜

0.45%, Si;

less than 0.10%, Mn;

more than 0.40%˜

less than 1.00%, P;

less than 0.010%, S;

0.010% or less, Cr;

0.5% or more˜

less than 1.5%, Mo;

more than 0.35%˜

less than 1.5%, V;

more than 0.3%˜

1.0% or less, with the balance being Fe and unavoidable impurities, and which has excellent fire resistance and resistance to delayed fracture such that following relations <

3>

, <

4>

are satisfied;

TS≦

(1.1×

T+850)  

 

<

3>

TS≦

(550×

Ceq+1000)  

 

<

4>

where

TS;

tensile strength of the high strength bolt at room temperature (N/mm²)

T;

tempering temperature (°

C.)

Ceq;

carbon equivalent (%)

Ceq=C+(Mn/6)+(Si/24)+(Ni/40)+(Cr/5)+(Mo/4)+(V/14).