Anchor Bolt Capacity

According to ACI 318M-05

Appendix D

Introduction

• Batasan maximum fc’ yang diatur dalam ACI 318 adalah 70 MPauntuk cast-in anchor dan 55 MPa untuk post-installed anchor

• Load combination menggunakan Ultimate Strength Design

• Strength reduction factor (Ø)

Tension 0.80

Shear 0.75

General Requirement for Strenght of anchor

• Tension

1. Steel Strength of Anchor in Tension

2. Concrete Breakout Strength of Anchor

3. Pullout Strength in Anchor

4. Concrete Side-Face Blow Out

• Shear

1. Steel Strength of Anchor in Shear

2. Concrete Breakout Strength of Anchor

3. Concrete Pryout Strength of Anchor

Steel Strenght of Anchor in Tension

Kapasitas Anchor Bolt dihitung berdasarkan

rumus berikut :

NSA = n.Ase.futa

n : jumlah anchor

Asa : area of anchor bolt

futa : min (1.9fya or 860 MPa)

Concrete Breakout Strength of Anchor in Tension

Rumus kapasitas breakout strength adalah sebagai berikut

Single Anchor :

Group Anchor :

Concrete Breakout Strength of Anchor in Tension

Dimana :

ANC : projected concrete failure area of single anchor group

ANCO : projected concrete failure area of single anchor with an edge distance equal to 1.5hef

Nb : basic concrete breakout strength of single anchor in tension

Ψed,N : modification factor for edge effect

Ψc,N : modification factor for no cracking effect on service load

Ψcp,N : modification factor for post installed anchor. For cast in taken 1.0

Ψec,N : modification factor for anchor group loaded eccentrically in tension

Concrete Breakout Strength of Anchor in Tension

Perhitungan Nb :

Concrete Breakout Strength of Anchor in Tension

Calculate ANCO

Concrete Breakout Strength of Anchor in Tension

Calculate AN

Concrete Breakout Strength of Anchor in Tension

Calculate AN jika jarak ke pinggir anchor bolt kurang dari 1.5hef

Pull out strength of anchor in tension

Nominal Pullout Strength

For concrete indicate no cracking

Concrete Side-Face Blow Out in Tension

Single bolt capacity :

Group bolt capacity :

Steel Strength Anchor in Shear

Capacity of Single Bolt :

Concrete Breakout Strength Anchor in Shear

Capacity of Single Bolt :

Capacity of Group Bolt :

Concrete Breakout Strength of Anchor in Shear

Dimana :

AVC : projected concrete failure area of single anchor group

AVCO : projected concrete failure area of single anchor with an edge distance equal to 1.5hef

Vb : basic concrete breakout strength of single anchor in shear

Ψed,V : modification factor for edge effect

Ψc,V : modification factor for no cracking effect on service load

Ψec,V : modification factor for anchor group loaded eccentrically in tension

Concrete Breakout Strength of Anchor in Shear

Perhitungan Vb :

Concrete Breakout Strength of Anchor in Shear

Calculate AVCO

Concrete Breakout Strength of Anchor in Shear

Calculate AVC

Calculate AVC on edge

Concrete Breakout Strength of Anchor in Shear

Calculate AVC on group of anchor

Concrete Breakout Strength of Anchor in Shear

Calculate AVC if distance bolt to edge is very deep

Concrete Pryout Strength Anchor in Shear

Capacity of Single Bolt :

Capacity of Group Bolt :

Shear and Tension Interaction

Kesimpulan

Selain dengan kedalaman anchor, jarak antar anchor dan jarak anchor ke pinggir beton mempengaruhi kapasitas tension dan shear darianchor.