1. Anchor
Channel Systems
2. HAC
Portfolio
3. HAC
Applications
6.3.1 SEISMIC LOAD BEHAVIOR
Cyclic loads are a characteristic feature of actions acting on
structures and anchorages during earthquakes. During seismic
events, anchors used to connect structural and non-structural
elements to concrete are subjected to cyclic tension and cyclic
shear loads. Cycling loads may induce additional cracking
that can ultimately reduce the concrete capacity of the anchor.
This effect is reflected in figure 6.3.1.Incorrectly designed or
inadequately qualified anchors have caused severe damage and
failure of the connection.
5. Base material
6. Loading
6.3.1 SEISMIC LOAD DERIVATION FOR
NONSTRUCTURAL COMPONENTS —
ASCE 7-10, CHAPTER 13
ASCE 7-10: §12.14.3.1 Seismic Load Effect The seismic load
effect, E, shall be determined in accordance with the following:
1. F
or use in load combination 5 in ASCE 7-10 Section §2.3.2
or load combinations 5 and 6 in ASCE 7-10 Section §2.4.1, E
shall be determined in accordance with ASCE 7-10 Eq. 12.14-3
as follows:
E = E h +E v
(ASCE 7-10 Eq. §12.14-3)
2. For use in load combinations 7 in ASCE 7-10 Section §2.3.2
or load combination 8 in ASCE 7-10 Section §2.4.1, E shall be
determined in accordance with ASCE 7-10 Eq. §12.14-4 as
follows:
E = E h -E v
(ASCE 7-10 Eq. §12.14-3)
where
a) Cracking of concrete due to dead load
ASCE 7-10 §12.14.3.1.1 Horizontal Seismic Load Effect
The horizontal seismic load effect, E h , shall be determined in
accordance with Eq. §12.14-5 as follows:
10. Design
Software
where
F p = seismic design force
S DS = s pectral acceleration, short period, as determined from
ASCE 7-10 Section §11.4.4
a p = c
omponent amplification factor that varies from 1.00 to 2.50
(select appropriate value from ASCE 7-10 Table § 13.5-1 or
13.6-1)
ℓ p = c
omponent importance factor that varies from 1.00 to 1.50
(see ASCE 7-10 Section §13.1.3)
W p = component operating weight
R p = c
omponent response modification factor that varies from
1.00 to 12 (select appropriate value from ASCE 7-10 Table
§13.5-1 or §13.6-1)
z = height in structure of point of attachment of component with
respect to the base. For items at or below the base, z shall
be taken as 0. The value of z/h need not exceed 1.0
h = average roof height of structure with respect to the base
The force (F p ) shall be applied independently in at least two
orthogonal horizontal directions in combination with service
loads associated with the component, as appropriate. For
vertically cantilevered systems, however, the force F p shall
be assumed to act in any horizontal direction. In addition, the
component shall be designed for a concurrent vertical force
±0.2S DS W p . The redundancy factor, ρ, is permitted to be taken
equal to 1 and the overstrength factor, Ω 0 , does not apply.
ASCE 7-10 §12.14.3.1.2 Vertical Seismic Load Effect The vertical
seismic load effect, Ev, shall be determined in accordance with
Eq. §12.14-6 as follows:
E v = 0.2S DS D (ASCE 7-10 Eq. §12.14-6)
11. Best
Practices
12. Instructions
for Use
13. Field Fixes
14. Design
Example
5. (1.2 + 0.2S DS )D + QE + L + 0.2S
7. (0.9 – 0.2S DS )D + QE + 1.6H
Under seismic conditions, the direction of shear may not be
predictable. The full shear force should be assumed in any
direction for a safe design.
6.3.2 O
VERSTRENGTH FACTORS PER
ASCE 7-10
Overstrength factor is used to satisfy seismic detailing
requirement of ACI 318. Structures in Seismic Design
Category (SDC) C, D, E or F are designed to yield which
induces additional cracking in concrete. The objective of the
overstrength factor is to cope with the unpredictability of the
seismic forces and to avoid brittle failure (concrete failure) of
the anchorage in a seismic event. This can be achieved by
increasing the concrete capacity of the anchorage by increasing
the seismic load by the overstrength factor.
6.4.0 LOADS ON HANDRAIL AND
GUARDRAIL SYSTEMS —
ASCE 7-10
ASCE 7-10 §4.5.1
D = effect of dead load
EXCEPTION: The vertical seismic load effect, E v , is permitted to
be taken as zero for either of the following conditions: Further, all handrail and guardrail systems shall be designed to
resist a load of 50 lb/ft (pound-force per linear foot) (0.73 kN/m)
applied in any direction along the handrail or top rail.
The horizontal seismic design force (F p ) shall be applied at
the component’s center of gravity and distributed relative to
the component’s mass distribution and shall be determined in
accordance with Eq. ASCE 7-10 Eq. §13.3-1: 1. I n ASCE 7-10 Eqs. §12.4-3, 12.4-4, 12.4-7, and 12.14-8 where
S DS is equal to or less than 0.125.
(
0 . 4 a p S DS W p
F p =
1 + 2 z
h
R p
I p
)
(ASCE 7-10 Eq. §13.3-1)
F p is not required to be taken as greater than
F p ≤ 1.6S DS ℓ p W p
c) Cracking of concrete after a seismic event and F p shall not be taken as less than
Figure 6.3.1.1 — Cracks in a reinforced concrete member subjected to
cycling loads. F p ≥ 0.3S DS ℓ p W p
(ASCE 7-10 Eq. §13.3-2)
(ASCE 7-10 Eq. §13.3-3)
Q E = effects of horizontal seismic force from V or F p as specified
in ASCE 7-10 Sections §12.14.7.5, 12.14.8.1, and 13.3.1
where
S DS = design spectral response acceleration parameter at short
periods obtained from ASCE 7-10 §11.4.4
(ASCE 7-10 Eq. §12.14-5)
where
146
9. Special Anchor
Channel Design
All handrail and guardrail systems shall be designed to resist
a single concentrated load of 200 lb (0.89 kN) applied in any
direction at any point on the handrail or top rail and to transfer
this load through the supports to the structure to produce the
maximum load effect on the element being considered.
E h = Q E
b) Cracking of concrete due to seismic load
8. Reinforcing
Bar Anchorage
E = seismic load effect
E h = effect of horizontal seismic forces as defined in ASCE
7-10 Section §12.14.3.1.1
E v = effect of vertical seismic forces as defined in ASCE
7-10 Section §12.14.3.1.2
7. Anchor Channel
Design Code
6.3.0 SEISMIC LOADING
4. Design
Introduction
2. In ASCE 7-10 Eqs. §12.14-4 where determining demands on
the soil-structure interface of foundations.
ASCE 7-10 §12.14.3.1.3 Seismic Load Combinations Where
the prescribed seismic load effect, E, defined in ASCE 7-10
Section §12.14.3.1 is combined with the effects of other
loads as set forth in ASCE 7-10 Chapter 2, the following
seismic load combinations for structures not subject to
flood or atmospheric ice loads shall be used in lieu of the
seismic load combinations in Sections ASCE 7-10 Sections
§2.3.2 or 2.4.1:
Basic Combinations for Strength design (see ASCE 7-10
Sections §2.3.2 and 2.2 for notation).
Cast-In Anchor Channel Product Guide, Edition 1 • 02/2019
147