SCT2a Slide 1 National Urban Search & Rescue Response System Structural Collapse Technician Training...

SCT2a Slide 1

National Urban Search & Rescue Response System

Structural Collapse Technician Training

Structural Collapse Technician Training-Ver.

3.1

Module : 2a

Shoring Basics

Jul12

SCT2a Slide 2



Terminal Objectives The Student shall understand the function &

capacity of the Shoring used in US&R to support damaged structures

The Student should also understand why and how these Shores are constructed

Basic DefinitionShoring for US&R is the TEMPORARY

Support of Only That Part of a Damaged Structure that is REQUIRED for Conducting

Operations at REDUCED RISK

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Key Learning Points - 1 What is Size and Type of Load that needs to

be supported?The weight of the supporting structure plus its

overload, or just its overloadBroken Structure or Rigid Structure

How much Shoring do you need?Should Shoring be similar to a Life Jacket? –

providing just enough lift to keep one afloatSome portion of the load can be (is being)

carried by the un-shored structure

SCT2a Slide 4



Key Learning Points - 2 What is the Capacity for the various types of

US&R Shoring Systems? How to configure US&R Shoring to ensure a

predictable & slow Failure Mode How to sequence the construction of US&R

shoring in order to Minimize RiskWhat are initial, short-term systemsWhat are more long-term systemsWhat are Class 1, 2, & 3 SystemsWhat is sequence in Multi-Story Shoring?

How and When to Inspect US&R Shoring

SCT2a Slide 5



USACE FOG & SOG

Sect 1 Haz ID + Marking Sys

Sect 2 Vert Shoring

Sect 3 Lateral Shoring

Sect 4 Repair Techniques FAQ & Glossary SOG has added Eng Tables

Sect 5 Equip Ops Procedures

Sect 6 Reference Data

Sect 7 Engineering Tables

Sect 8 USACE StS Deployment Ck-Lists

Sect 9 FEMA StS Deployment Ck-Lists & Forms

Sect 1-4Sect 1-9

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Collect Load

Distribute Load

Double Funnel Principle

Need Posts / Shores with Adjustability & Positive Connections

Need Lateral Bracing Need System with Forgiveness

SCT2a Slide 7



Weights of Building Materials Reinforced concrete = 150 pcf

Concrete columns & beams weigh more (16"sq w/ 5% rebar = 170pcf)

Masonry = 125 pcf Wood = 35 pcf (dry) Steel = 490 pcf Concrete or masonry rubble = 10 psf per inch

SCT2a Slide 8



Quick way to estimate weightsBase estimate on approximate weight per square foot for unit thickness of concrete (12") and steel (1") 12" conc slab = 150 psf

10' conc slab = 125psf8" conc slab = 100psf6" conc slab = 75psf (and so on)

1" steel plate = 40psf¾" steel pl = 30psf½" steel pl = 20psf¼" steel pl = 10psf (and so on)

SCT2a Slide 9



Weights of Building Construction Concrete floors = 90 to 150 psf

Light weight concrete is about 80% Steel systems w/ conc fill slabs = 50 to 70 psf

Wood floor = 10 to 25 psf

(post 1960 wood floors may have concrete fill) Add 10 to 15 psf for wood/metal interior walls

each floor Add 10 psf or more each floor or furniture etc.

More for storage Add 10 psf or more for Rescuers

SCT2a Slide 10



Example Assume that this 20ft x 30ft classroom has an

8" thick concrete roof with 6" of debris on it WHAT IS THE TOTAL LOAD TO SHORE ?8" concrete = 100 psf x 20 x 30 = 60,000 lb6" debris = 60 psf x 20 x 30 = 36,000 lbLights, ducts, ceiling, etc. = 5 psf = 3,000 lbRescuers = 10 psf x 20 x 30 = 6,000 lb*TOTAL (105 Kips) = 105,000 lb

* 6,000 lb Rescuers allows for 24 - 250 lb FFIs this reasonable ? If not use more, this is a MINIMUM

SCT2a Slide 11


Structural Collapse Technician Training Shoring in Multi-story Structures For Existing, "Sound" Buildings - Only

Wood Building: one undamaged floor can support one damaged floor

Steel Building: 2 undamaged for 1 damagedReinforced Concrete: 3 for 1Precast Concrete: start at ground

Assumptions"Normal" loading - no heavy debris, etcNot for buildings under construction

See Manual & Input from StS

Not for any buildings that collapse unexpectedly – w/o Quake, Blast, etc

SCT2a Slide 12



Shoring in Multi-story Structures – cont. Sequence for multi-story Shoring –

Where do you start?Start directly under lowest "Damaged" or

"Overloaded" Floor in order to share the loadKeep shoring in all stories vertically aligned

Other StrategiesShore from Outside - InShore for Team Access & EgressPhased approach – see next slide

Spot shore - Class 1 2 Dimensional - Class 23 Dimensional - Class 3

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Class 1 – Class 2 – Class 3

T Shore – 2 Post Vertical – Laced Post

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Shoring Selection Considerations Condition of damaged floor / wall

Solid with cracks Badly cracked concrete or masonryWood joist - Wood trussSteel beam - Steel bar joistPC Concrete - T, Dbl T, I-Beam, Slab

(hollow sections)

SCT2a Slide 15



Shoring Selection Considerations Condition of supporting surface

Solid ground - slab on groundRubble covered ground or slabUndamaged floors in multi-story bldg Basement - but now many floors below

Availability of shoring materials & local contractors

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Shoring Selection Considerations Damaged buildings often contain

vertical as well as lateral instabilities Uncollapsed building have been 10%

out of plumb in one story (requires lateral shoring to support 10% of total weight of building + aftershock)StS needs to design

SCT2a Slide 17


Structural Collapse Technician Training Building Out of Plumb ForcesBuilding Out of Plumb Forces

1ft

1

100K10K

10ft

SCT2a Slide 18



Shoring Selection Considerations Collapses with large pieces may have

unseen interdependencies Sloped floors & walls are difficult.

Loads are vertical due to gravity Contact surfaces are sloped and lateral

forces need to be considered and resisted.

SCT2a Slide 19



Needs for Shoring Systems Easy to calculate Total Load of structure Don't know where load is concentrated Similar to mine collapse - unknown load

distribution Shoring system must give warning of

overloadNeed recognizable "Structural Fuses"

Brittle failure mode is highly undesirableAvoid systems that have Buckling Failure

SCT2a Slide 20


Structural Collapse Technician Training Use Unique Property of Timber To Provide Warning of Overload Growth pattern of tree Rapid growth in spring deposits

relatively soft fiber Slower growth rate in summer

deposits more dense fiber If load end grain, crushing strength is

determined by summerwood If load is on side (cross-grain), soft

springwood determines strength Cross-grain bearing failure is slow and

noisy - (gives warning)

SCT2a Slide 21



Capacity Of Wood Posts Slenderness (L/D) determines the buckling

strength of a wood post (L/D = length/width)Buckling failure is sudden and undesirableThe maximum allowable L/D is 50

For better failure mode posts should be constructed so their L/D is less than 25This will insure that cross-grain crushing can

occur and be observed at a load that is lower than the Buckling Load.

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Example of wood joint with good

performance

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Capacity of Wood Posts For L/D to be 25 or Less

4 x 4 should be kept shorter than 8 feet6 x 6 should be kept shorter than 12 feet

This is not always possible If a post is properly braced at its mid-height,

its Effective length is half its Total length.Bracing must be placed in N-S as well as E-W

direction and properly nailed FEMA, US&R shoring has lots of bracing

SCT2a Slide 24



Vertical Shoring Systems Wood Posts Ellis Clamps

& Jacks T - Spot Shore Window / Door Laced Posts Ply Laced Posts

Cribbing Steel Pipe Metal Frames

& Joist Pneumatic Shores

Shores for Sloped

Surfaces

SCT2a Slide 25



US&R Shoring Terminology Header Sole Plate Post Wall Plate Raker Raker Cleat Gussets

Diag brac'g Ply Braces

Collects load at roof and floorTransmits load to floor or ground4x4 or 6x6 from header to soleCollects load from wall/vert. surface4x4 or 6x6 from wall plate to sole 18" to 30" 2x connection pieces5/8 or 3/4 Ply (or OSB) connections( 12"x12" full, 6"x12" half, 12"x24"

double)2x4, 6 as X or V between shores 8" & 24" wide ply horiz. braces at PLP

SCT2a Slide 26



Vertical Wood Shore – Class 2• Plywood half-gussets to

post, 1 side at top with 4x4 & 6x6 header (Dbl gusset + add on opp. side of diag brace at bottom)

• 2x6 diag braces

• 1x6 brace for 4x4 > 8' (3/4" x 6" ply is alternative)

• Full width wedges w/ keeper nails.

• Nail 2x6 diag. brace w/5-16d to sole, header, & each post (may use 3-16d to post at bottom)

SCT2a Slide 27



Load Path - Vertical Load Load

Resistance

SCT2a Slide 28



Load Path - Lateral Load

Load

Everything reverses

when Load comes from

the Left

Load

Resistance

Resistance

SCT2a Slide 29



Vertical Shore - Important Joints 2x6 diagonal needs to be carefully

positionedTo provide a competent load path To fit 5-16d to header, post & sole

May use 3-16d to post at bottom

To confine wedges and reduce roll over at bottom

For most long-incidents, need to add gusset on opposite side of diagonal brace to protect against sole roll-over & wedge pop-out

post

sole

header

SCT2a Slide 30



Vertical Wood Shores 4x4 Posts System with 4x4 Sole

* = based on 660 psi cross-grain bearing

Header SizeUse 4x4 min. if posts are placed directly under floor beams or when supporting intact/rigid concrete slab or beam. See Structures Spec for other conditions

H = Height

Design Load Each Post

8' -0" 8,000# *

10' -0" 5,000#

12' -0" 3,500#

SCT2a Slide 31



Vertical Wood Shores 6x6 Post System with 6x6 Sole

H = Height

Design Load Each Post

12' -0" 20,000# * 14' -0" 14,500# 16' -0" 12,000# 18' -0" 9,000# 20' -0" 7,500#

* = based on 660 psi cross-grain bearing

Header SizeUse 6x6 min. if posts are placed directly under floor beams or when supporting intact/rigid concrete slab or beam. See Structures Spec for other conditions.

SCT2a Slide 32



Assumptions - Vertical Shore Configurations show Post Design Load for

given heights The 4x4 and 6x6 Header Size assumes:

Posts are 4 ft max o.c.Post are aligned with floor beams Or that supported concrete is rigid enough to

span between posts If not the case - StS must design header

Max. slope of floor/header is 5% (6" in 10')

SCT2a Slide 33



Properties Of Good Wood Minimum of 8 Rings per Inch Slope of Grain = 8 to 1 or Less Maximum Tight Knot = 1 1/2 in. Maximum Loose Knot = 3/4 in. If Doug Fir or Southern Pine have this

type of grain, Factor of Safety = 2 ?

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Vertical ShoreShort Term & Light Load

For Light Frame where no displacement due to lateral loads, vibration or load

shifting is likely

SCT2a Slide 35


Structural Collapse Technician Training Vertical Shore – Fully connected systemGussets each side at sole to restrain wedges

SCT2a Slide 36



2-Post Vertical Wood Shores• Plywood half-gussets ea. side

each post, except at diagonal (gussets only one side for 4x4, 6x6 Header)

• 2x4 diagonal brace w/3-16d ea end & to posts (7'-6" max long to resist tension/compression)

• 2x4 mid brace

• 4x4 Posts at 4' max. o.c. (5'max. o.c. at 6x6)

• 2x wedges w/ toenails

Same as One Face of Laced Post Shore

SCT2a Slide 37



2 Post Vertical Shore

Built during training(Diagonals may be in any configuration, K or parallel)

SCT2a Slide 38


Structural Collapse Technician Training 2 Post Vertical Shore - Limited Height

• Plywood half-gussets ea. side each post, except at diagonal (gussets only one side for 4x4, 6x6 Header)

• 2x6 diagonal brace w/5-16d to sole, header & to post (7'-6" max long to resist tension & compression)

• 4x4 Posts at 4' max. o.c. (5' max. o.c. at 6x6)

• Full width 2x wedges w/ keeper nails.

6' Max. Height of Shore

SCT2a Slide 39



2-Post Vert ShoreStacked 2 high in multi-floor collapse

SCT2a Slide 40


Structural Collapse Technician Training 880 Freeway using 12x12 & Steel W as sole, no connections or bracing

Vertical Shores

SCT2a Slide 41


Structural Collapse Technician Training Vertical Shores - 880 Freeway Using 12x shores & sole, no connections & bracing

SCT2a Slide 42



Ellis Shores - 4x4 adjustable Need 2 Ellis Clamps to make a

pair of 4x4 into Adjustable 4x4 shore

Need Ellis Jack Failure Mode is by clamp

crushing the side grain of the post - Gives Warning

Design Load = 6000 lb Not in current cache

12-0

max

7-0

max

6"12

"6"

SCT2a Slide 43



Screw Jack by Ellis Adjustable metal foot for 4x4

and 6x6 wood posts 6 inch adjustment - set half

way to get 3 in. up & down Metal Foot is stronger than

wood post Use sole to spread load

SCT2a Slide 44



Ellis Foot was used in Half Mile Tunnel Under Kansas Grain Elevator that Exploded

Closure doors were blown off the bottoms of cylinders

& grain filled the tunnel

SCT2a Slide 45


Structural Collapse Technician Training Ellis foot used to develop friction conn. To support new closures

Plywood closures stopped the grain flow so tunnel could be emptied using a

large vacuum

SCT2a Slide 46



T - Spot Shore – Class 1

Post strength isLimited by stability

2 ft to 3 ft sole plate, same size as header

Design Load = 1k?

Temporary Shore

Basically Unstable

Typical header is 3 ft and centered on Load

Dbl T is more stable

11 ft Max Height(10'-3" Post)

FullGusset

HalfGusset

SCT2a Slide 47



T shores & Ellis Foot

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The Dbl "T" Shore – Class 2

More Stable than T Shore, but weighs about 25 lb more

3 ft header & sole

Posts from 18" to 24" out-to-out

Design Load, based on 2-Posts (length)

A little harder to move into place

Ply dbl gusset1-side, mid-height

12"x 24"Plywood dbl gusset ea side

HalfGusset

HalfGusset

SCT2a Slide 49



Dbl "T" Shore – easy to install Shore Top Chord of Truss Shore Wood Apartment

SCT2a Slide 50



The Dbl "T" Configuration Depends on

Height

Less than 6 ft HighNo Mid Height Ply Gusset

Up to 12 ft High One Mid Ht Gusset

Max Height is 12 ft

(11'-3"Post)

SCT2a Slide 51



Window / Door ShoreToo complicated ? For opening in

URM & Wood walls

Capacity of shortposts based onBearing Strength

Header should be1" deep for each1' of opening width

X bracing may be removedfor access

Be careful oflimited bearing

Ply half-gusset

Diagonal cleat at upper wedges

Cleats to confinewedges + post

to sill connection

SCT2a Slide 52



Alternate - Window / Door ShorePre-construct as box-frame, 1 ½" min. less than opening

Add wedges on bottom and one side at top and bottom

Add diagonal bracesif wall is racked, and access isn't required

Plywoodhalf-gussetseach sideeach corner

SCT2a Slide 53



Window Shores

Construct In-placePre-fabricated

SCT2a Slide 54



Laced Posts - Class 3 4x4 Posts=4ft max o.c.

6x6 Posts = 5 ft max. o.c. Increase post capacity due to

short effective length Maximum Post Height:

17ft with 4x4 posts, 20ft with 6x6 2x4 lacing, 3-16d each end

3 bracing bays, 11ft to 17ft high4 bracing bays, 17ft to 20ft high

Requires 6x6 Posts w/ 5ft spacingUse K layout or any other2x6 lacing, 5-16d at 6x6 Posts

Header & Sole w/ 1ft overhang Connections like Vertical Shore

Design Load (660psi bearing)

4 - 4x4 x 17"- 0"max. = 32,000# 4 - 6x6 x 20'- 0" max. = 80,000#

Can be used as Safe Haven

SCT2a Slide 55



Laced Posts - Connections Need to carefully place diagonal

at post to beam and post to soleNail 3-16d to beam & post at topNail 3-16d to sole & post at bottom

+ confine wedges Use gusset, one side at other

post to beam & each side to sole (+ opposite side diagonal)5-8d to post8-8d to beam & sole

SCT2a Slide 56


Structural Collapse Technician Training Laced Post ExamplesOver 11 ft Up to 11 ft

SCT2a Slide 57



Laced Posts Prefab

Change to Half-Gussets

Test

SCT2a Slide 58



Laced Post – Class 3 Limited Height Area

For less than 6 ft high spaces

4x4 Posts=4ft max o.c.6x6 Posts = 5 ft max. o.c.

Built as a half high Standard Laced Post

As for all "Vertical" shores, headers may slope up to 6" in 10 ft

SCT2a Slide 59



Use 4x4 or 6x6 posts Min ht=4ft; Max ht = 17ft Use 5/8 or 3/4 ply braces

Mid-plywood braces are 24"x 48"11-8d nails each endOne level of braces, 4' to 9' high 2 levels of braces 9' to 13'high 3 levels of braces 13' to 17' highTop & bott. braces are 8"x 48"

6' long header & sole Connections like Vertical Shore2x4 wedges on sole (2x6 at 6x6)

Design Load (660psi bearing)

4 - 4x4x17"- 0"max. = 32,000# 4 - 6x6x17'- 0"max. = 80,000#

Plywood Laced Posts - Class 3With 4ft x 4ft out to out Post Spacing

SCT2a Slide 60



Plywood Laced Posts - Class 3With 2ft x 4ft out to out Post Spacing Use 4x4 or 6x6 posts. Min ht.=4ft; Max ht.=13ft Use 5/8 or 3/4 ply braces

Mid-plyw'd braces are 24"x 48"and 24"x 24", with 11-8d nails each end.

One level of braces, 4' to 9' highTwo levels of braces 9' to 13'high.Top & bott. braces (4'side) are 8"x48"

4ft long header & sole Double gusset one side at headerHalf gusset ea. side at sole & wedges

Design Load (660psi bearing)4 - 4x4x13'- 0"max. = 32,000# 4 - 6x6x13'- 0"max. = 80,000#

SCT2a Slide 61



Wood Cribbing – Class 1? Capacity based on cross-grain

bearing area of system Allow stress varies from 200 to

1000psi for wood species For 2 member x 2 member crib

4x4 Design Load = 24,000# (500psi) 6x6 Design Load = 60,000#

Limit Height to Width to 3 to 1*See recommended height limit below

Stability and Deflection IssuesCrib can crush as much as 20% *Recommended to Limit Ht to 4 ft for

4x lumber & 6 ft for 6xOverlap corners 4" minimum

SCT2a Slide 62



Cribbing Layout

2 X 2 3 X 3 Solid Bearing

Triangle Parallelogram

W W

Both these not very stable. KeepHt to W 1 to 1 max

SCT2a Slide 63



4x4 Cribbing w/ 4 Bearings

6000# eachcontact

6000# eachcontact

Load on all cornersMost Stable - Ht to W = 3 to 1 max

Poor choice since loading is non-uniformKeep Ht to W within 1 1/2 to 1

6000# eachcontact

6000# eachcontact

SCT2a Slide 64



Pentagon 6x6 Cribbing at

Front of Collapse Zone

Current Recommendation is to limit height of 6x cribbing to

6 ft due to stability concerns

SCT2a Slide 65


Structural Collapse Technician Training 4x4 Wood Box Crib Test

Load = 17k Slab + 25k BlocksTotal Load = 42k = 870psi Deflection. = 6" (24k Design)

Before After

SCT2a Slide 66



Pipe Shores – Class 1 Not in US&R Equipment Cache Rent from Concrete Service Co. Design Load based on diameter &

length of shore 2"dia. pipe x 10-0 = 6,000#

1 1/2" dia. x 7-0 = 6,000# Design Capacity of system using

wood header and sole may depend on base plate area

SCT2a Slide 67



Pipe Shores - OKC - high L/D

SCT2a Slide 68



Aluminum Frames – Class 3 Available in 20k per 2

leg frame up to 50k Design Capacity of

frame may depend on foot bearing plate

Aluma Beams have wood nailer and can span up to 20' Have been used as

shield/shelter

SCT2a Slide 69


Structural Collapse Technician Training Alum Frames at OKC

Frames used after 1971 L.A. Quake

Small roof load, 18ft high

SCT2a Slide 70



Aluma Beams

Available from Concrete Supply (Burke) Up to 20 ft spans - use Plywd Sheathing Good Dynamic Properties to stop falling

objects more slowly - absorb energy

Aluma Stringer Beam 140 Beam

7 1/2"191 mm 6 1/2"

165 mm 5 1/2"140 mm

3s

SCT2a Slide 71


Structural Collapse Technician Training Puerto Rico - Aluma Beam Platforms used to shields from falling hazards

Two levels of Aluma Beams +

plywood w/Rescue working under

SCT2a Slide 72



Pneumatic Shores – Class 1 Adjustable Shore up to 16 ft long

Manufactured by Hurst-Airshore and Paratech

Have Swivel & other feet Hand tighten (snug) using

adjustable collar or sleeve nut May use up to 50psi air pressure

to raise into position Design Strength decreases with

length and should be based on tests using swivel ends

Best use is as Initial, Spot Shore

SCT2a Slide 73



What About using Extensions for Pneumatic Shores? Don't use extensions unless you have to Shipping Pallet size is 104" x 84"

this is a problem for 10' to 16' Strut Extensions available in lengths from 1' to 6' Joint between Strut & Extension must be

tested to demonstrate adequate strength Paratech & Hurst-Airshore have

successfully tested their joints and recommendations for struts used with one extension are included in the SS FOG and the following slides

SCT2a Slide 74



Strut Extensions

3 ½"3 ½"

Good One

Do Not Use this one3" 3 ½"

Airshore Problem

Paratech Extension OK

SCT2a Slide 75



Recommended Design Strengthfor Hurst-Airshore Struts used in US&RLength Load Comment

16 ft 3000 lbs May use one 6ft extension 15 3400 “ 14 3800 May use one 6ft or 4ft 13 5000 extension 12 7000 May use one extension 11 10000 “ 10 12000 Do not use extensions 9 14000 “ 8 15000 “ 7 18000 “ 6 & less 20000 “

SCT2a Slide 76



3- Column – at Pentagon Spot Shores – 14ft high

Design Strength = 12K

(Design Strength, 1 - 6x6 = 14.5K)

Hurst-AirshoreStruts

SCT2a Slide 77


Structural Collapse Technician Training Recommended Design StrengthFor Paratech Long Shore Struts in US&R Paratech Long Shore Struts are 3½" in

diameter (Gold Anodized), which is larger than original 3 " dia. Paratech Rescue Struts.

Paratech Rescue Struts (3" dia., Dark Grey) should be used ONLY up to 8 feet longThey have a strength similar to the 3½" struts for

lengths up to 6 feetStrength drops to about 14,000 lb for 8 ft See Manufacturer’s recommendations following.

SCT2a Slide 78



Recommended Design Strength For Paratech Long Shore Struts in US&RLength Load Comment

16 ft 3500 lbs May use one 6ft extension 15 4500 “ 14 5500 May use one 6 or 4ft ext. 13 6500 “ 12 7500 May use one extension 11 10000 “ 10 12000 “ 9 16000 Do Not Use Extensions 8 20000 “ 7 & 6 22000 “

SCT2a Slide 79



PARATECH Rescue Struts – Load TableBased on Tests by Paratech, Reviewed by Wiss, Janney, Elstner, Engineers

Available from 1.5 to 7ftExtensions avail. In 12", 24" and 36" lengths(use max. of one extension per strut)Length Ave Ult Design Strength

Based on Safety Factors 3 to 1 4 to 1 2 ft 87,000 lb 29,000 lb 21,750 lb 4 ft 71,750 lb 23,920 lb 17,940 lb 6 ft 56,500 lb 18,830 lb 14,125 lb 8 ft 48,100 lb 16,030 lb 12,025 lb

SCT2a Slide 80


Structural Collapse Technician Training Paratech Rescue Strut used in Turkey

SCT2a Slide 81



Shores for Sloped Floors – Class 3In Normal Construction, one cutsLevel Bearings in Wood Rafters (Birds Mouth)

WE CAN'T DO THISUNSAFE AND NOT PRACTICAL

Since bearings are level, loads are transferred vertically without generating any sloped forces

Not the case for Sloped Floor Shores

SCT2a Slide 82



Shores for Sloped Floors Sloped Floor is defined as over 5%

6 inches in 10 feet Build them in pairs with bracing between

Similar to Laced Posts = Class 3 There are basically 3 designs:

Perpendicular to Slope MethodType 2 (Type 1 is no longer recommended)

Friction Method – Type 3Cribbing – Type 4

30% (3 ft in 10 ft) max. slope

SCT2a Slide 83



Shores For Sloped FloorsPerpendicular to Slope Method

Slope force dependson degree of slope

Force in shore isperpendicular tocontact surface

To shore sloped surfaces we must provide a system that will resist both vertical & lateral forces

Bearing load directionis perpendicular tocontact surface betweenshore and structureSloped force resisted here or by remaining structure

Gravity Load

Concrete Floor Slab (may be connected

to remaining structure)

SCT2a Slide 84



Type 2 – Sloped Floor Shores

Type 2 - On Concrete, Paving or Soil(Perpendicular to Slope Method)

Bearing force isperpendicular to shore & slope force parallel to slab

GravityLoad

Header4x4, 6x6 Shores cut to bear2 ways at bottom

2x Bracing Nailed cleats

Slope force needsto be resisted by rubble & ground

Gravity load resisted Sole must bekept from sliding

Add 3-2x6x18" under each post on soil

Use half-gussets ea side posts top & bott.except at diagonals

SCT2a Slide 85


Structural Collapse Technician Training Type 2 - Sloped Floor ShoreHalf-Gusset at bottom left off to show cuts at joint

Type 3

SCT2a Slide 86



Type 3 – Sloped Floor ShoresWhat to do if Sloped floor is NOT connected to Remaining Structure or Embedded in Rubble

Type 3 - Friction Method (On Concrete, Paving or Soil) (For slopes over 5% need Connection between Header & Slab)

No ReliableResistance

System with shaped top - vertical shores,cut to mate with cleats & header will transfer both the sloped & perpendicular forces

GravityLoad

GravityLoad

Concrete Slab

Vert. load resisted by ground

Anchor

Gravity load in floor is resisted by sloped friction Force + Force perpendicular to Sloped surface

Drill-ins

Add 3-2x6x18" under each post on soil

SCT2a Slide 87


Structural Collapse Technician Training Type 3 - Sloped Floor Shore Half-Gusset at top left off to show cuts at joint

Type 3

SCT2a Slide 88



Type 3 - Sloped Floor Shore Shown without optional wedges

Type 3

SCT2a Slide 89



Type 3 - Sloped Floor Shore Friction Method

Type 3

Use half-gusset

SCT2a Slide 90



Some Practical Solutions

Vertical Shore on angle

w/raker-like sole & cleats

More like a Flying Raker

SCT2a Slide 91



Lateral Bracing For Paired Sloped Floor Shores

For pairs of shores, spaced up to 5 ft o.c. use bracing between shores as in Laced Posts.

or For pairs of shores, spaced up to 5 ft o.c. use

solid plywood strip when height is 3 ft and less.or

For 2 or more shores, spaced up to 8 ft o.c. , use longitudinal and X and/or V bracing as in Raker Shores.

SCT2a Slide 92



Slope Floor Lacing

Shores up to 5 ft o.c.

2x6 or 2-2x4

SCT2a Slide 93



Slope Floor BraceWhen too short for lacing

12" to 24"- 5/8 or 3/4" plywood strip2 rows 8d @ 3" o.c. to posts

Shores up to 5 ft o.c.

12" max

12" max

SCT2a Slide 94



Slope Floor X Bracing

Shores 8 ft max. o.c.

2x6 or 2-2x4

SCT2a Slide 95



Shores For Sloped Floors Cribbing - Type 4

Bottom layer needs to be solid to spread load

4x, 6x set in from corners

Force in crib will bemostly vertical, buthave horiz forces dueto slope & aftershock

Slope forces areoften resisted byfriction

Sloped Floor

GravityLoad

Bearing Force

Center of loadshould be containedwithin mid half crib

Build cribbing intoload by adding 1xnailed to crib 4x

Option- add 3/8"min plyw'd strips with 8d@3" each edgefor lateral strength

SCT2a Slide 96



Crib at sloped slab in OKC

Type 4

SCT2a Slide 97


Structural Collapse Technician Training Summary for Sloped Floor Shores - 1 No simple, "one fits all conditions answer"

Need to resist load in direction it's tending to move Wood floors need header perpendicular to joist.Use Vertical Shores for slopes up to 5% (6" in 10 ft)

Type 2, Perpendicular Bearing Method may work most of the time for concrete floors, since they often remain connected to structure.

Type 3, Sloped Friction Method needs a connection between header & floor.

Use cribbing up to 4 ft high & up to 30% slope (30% slope is 3 ft in 10 ft, and about 15 degrees)

SCT2a Slide 98



Summary for Sloped Floor Shores -2 Design Load for pair of braced, Sloped Floor

Shores using 4x4 posts: May be assumed to be 24k for angles up to 15 degrees

(3 ft in 10 ft) – 60k when using 4-6x6 PostsThe angles and adequacy of the bracing can reduce

the strength, especially for steeper anglesThe capacity of the sole anchor is criticalThe StS should always determine the Design Load

At angles above 45 degrees, consider other alternatives

SCT2a Slide 99



Lateral Shoring Systems

Horizontal Shores Trench Shores Raker Shores Tiebacks

SCT2a Slide 100



Wood Horizontal Shore

Used to brace bulgingwalls, usually URM

If posts are short,capacity is based oncross grain bearing

X bracing is removedfor access & use half gusset connections

Spaced 8' o.c. maximum.

Cleats one side at wedges

Half Gusset

SCT2a Slide 101



Hydraulic Trench Shores Aluminum hydraulic

rams w/side rails Pressurized w/5 gal hand

pump to 500 - 1000 psi Installed w/special

plywood sheathing Spacing depends on Soil

Type, Depth & Width Must maintain pressure

to carry load - no lock

SCT2a Slide 102



Other Trench Shores Trench Jack - same capacity

as vertical

Post Screw Jack - same as vertical

Pneumatic Shores - same as vertical (intended as trench shores and are first extended w/ air pressure and then set with nut or pin for positive connection)

USE MFR'S PIN END VALUES

SCT2a Slide 103



One Side Trench Shore Need Design by StS Bracing Frames at 4’ o.c. Better to use 30deg Slope 4x4 or 6x6 members

Depends on Height & SoilClass C Soil (80h+ 72)psf

Need 3x or 4x sheathing Need very good Anchor Sys Need perpendicular 2x6

horizontal & X- bracing Sys

SCT2a Slide 104



Diagonal - Raker Shores

Raker Shore = Diagonal4x, 6x timber or other.Need to keep effective length reasonably short by using lateral bracing

Apply horizontal force to stabilize structure

Vertical force tends to move shore up the wall. To resist this shore needs to bear on ledge or be connected to wall w/ anchors, etc.

Horizontal reaction is resisted by sole anchor, pickets into paving or ground, push on curb, etc.

Vertical reaction is resisted bypaving or ground using foot.

Insertion Point

SCT2a Slide 105



Poorly organized raker Brownsville, TX best quick shore here is Front End Loader

SCT2a Slide 106


Structural Collapse Technician Training Rakers, S.Cruz, 89 EQ Not effective, too steep & no conn to wall

SCT2a Slide 107


Structural Collapse Technician Training Raker in SF 89 Loma Prieta Quake By Struct. Eng., protect Day Care Center

SCT2a Slide 108


Structural Collapse Technician Training Raker by S.E. in 89 Loma Prieta Quake

Cleats w/drill-ins

to URM

Concrete Footing

FEMA Raker Systems are Next

SCT2a Slide 109



Flying (Friction) Raker (Spot Shore)

Raker

BottomBrace

Best use Flying Raker is as initial, shore until more reliable system can be built.Use Trough Base – on concrete, paving or soil (next slide)

4x4 wall plate & rakers w/2x6 bott. brace or 4x6 wall plate, 6x6 raker & 2x6 bott. Brace

Ply gussets each side, raker to plateNeed to connect wall plate to wall (wall plate is 6‘ long & bottom brace is level)

5/8"or 3/4" backing at wood wallsand badly cracked conc./urm walls

Rubble

Wall Plate

SCT2a Slide 110


Structural Collapse Technician Training Trough Base (on conc., paving, or soil)

Trough to Raker w/5-16d ea. side

Place Picket ea. side TroughTo stabilize front endMay use 5/8x36" Pickets

Trough Base2-2x6x36" + 2x4x36"7 – 16d each sideAdd 2x4x18"Cleat5 – 16d to bottom, to be flush with end

Wedges

Sole Anchor (may pre-drill timber for pickets)6x6 x 48"minimum long or continuous4 – 1"x 48" Pickets into Soil, & 2 into Paving

Add 3-2x6x18"or2-3/4"x18"sq.Ply

at soft soil

SCT2a Slide 111


Structural Collapse Technician Training Full Triangle Raker - Solid Sole TypeClass 3 w/bracing – on Paving or Soil

Solid Sole

Solid sole w/ nailed cleat, wedgesand anchor system at end or drill-ins thru solid sole

4x4, 6x6 Raker depending on lengthand lateral & mid-point bracing

4x4, 4x6 Wall Plate w/ drill-ins to wall(OR plywood backing at wood or badly cracked concrete/URM walls)

2x nailed cleat, 14-16d min. at 2x4(20-16d with 30" cleat for 60 deg).

2x6 mid-braces to reduce L/d of raker

Build these away from wall andassemble at wall in pairs or moreas system with lateral bracing

Add 3-2x6x18" under sole on soil

Sole Anchor

Ply Gussetseach side

SCT2a Slide 112



Rescue Spec Training Class built Rakers

SCT2a Slide 113


Structural Collapse Technician Training Rakers installed after Explosion Blew out part of URM cavity wall - 1 story bldg

Needed entry here

SCT2a Slide 114



Full Triangle Raker - Split Sole Type Class 3 w/bracing

4x4, 6x6 Raker depending on lengthand lateral & mid-point bracing

4x4, 4x6 Wall Plate w/ drill-ins to wall(OR plywood backing at wood or badly cracked concrete/URM walls)

2x nailed cleat, 14-16d min. at 2x4(20-16d with 30" cleat for 60 deg)

Build these away from wall andassemble at wall in pairs or moreas system with lateral bracing

2-2x6 Split Sole (4x4 mid block if over 7ft long)

Trough Base on concrete, paving, or soil

Sole Anchor

SCT2a Slide 115


Structural Collapse Technician Training Class built Split Sole Rakersw/Trough Base

Slope Bottom Brace over rubble

Level Bottom Brace No rubble

SCT2a Slide 116



Raker Shore Systems – Class 3 Build individual rakers away

from wall & assemble as System w/bracing

Rakers using 4x4 are most common and require L/d plus Lateral Bracing in order to achieve the height required to brace most URM walls

Use 2x6 struts at mid height with X or V bracing

Double raker is shown, is reqd to brace 2 & 3 story walls

SCT2a Slide 117



Effect Of Raker Angle1k (1000 lb) in Raker

Approximate Horizontal Design Capacity of RakersFull Triangle Rakers is about 2.5 k

Based on Cleat Nailing + FrictionFlying Raker is about 1k

For 4 x 4 Raker, due to compression plus bending

30 Degree 45 Degree 60 Degree

.87k

.5k .7k

.7k

.5k

.87k

SCT2a Slide 118



Split Sole - Full Triangle Raker

20ft system = 270#16ft system = 220#

SCT2a Slide 119


Structural Collapse Technician Training Bracing for Raker Systems

2x6 horiz braces

Rakers @ 8'o.c.

Raker Bracing Elevation

2x4 or 2x6 Diagonal Braces in V or X - Use one set each 32 ft max

Use 5 nail patternat 2x6 & 3 nails at 2x4 (16d)

SCT2a Slide 120



Solid Sole Full Triangle Raker

20ft system = 265#16ft system = 225#

SCT2a Slide 121


Structural Collapse Technician Training Pneumatic Shores Used As Rakers Raker = 2 struts + special rail

Has base plate + special conn. Anchor base plate to paving

w/steel bars or drill-ins. Add steel angle under base

plate to bear on typical anch pl Can be used in system w/ horiz.

& diag. 2x6 bracing Need to pin rail to wall. Best used as initial shore

followed by wood system Use mid-brace & dbl X bracing

for raker over 11ft long 2s

SCT2a Slide 122



Airshore Raker - Class 3

With mid-brace Without mid-brace

SCT2a Slide 123


Structural Collapse Technician Training Recommended Design Strengthfor Hurst-Airshore Raker System – 45 deg

Raker Length

Height to Insertion

Horiz. Design Load on 2 Rakers w/ X-bracing

16 ft 11.0 ft 4200 lbs 15 10.5 ft 4800 14 10.0 ft 5400 13 9.0 ft 7100 12 & less 8.5 ft 10,000 lbs

System is made from 2 rakers spaced 8ft max. apart with X-bracing.

Rakers need to be attached to wall surface and restrained at ground.

If raker is mid-braced (each way), use 10,000 lb.

SCT2a Slide 124


Structural Collapse Technician Training Recommended Design Strengthfor Hurst-Airshore Raker System – 60 deg

Raker Length

Height to Insertion


16 ft 13.8 ft 3000 lbs 15 13.0 ft 3400 14 12.0 ft 3800 13 11.3 ft 5000 12 10.4 ft 7100 11 & less 9.5 ft 10,000 lbs

2 rakers spaced 8ft max. apart with X-bracing Rakers need to be attached to wall surface and

restrained at ground. If raker is mid-braced (each way), use 10,000 lb.

SCT2a Slide 125



Paratech Raker – Class 3With mid-brace Without mid-brace

SCT2a Slide 126



Paratech Raker – Special configurationsDouble Raker With strut bracing

Flying Raker

SCT2a Slide 127



Paratech Raker Connection Details

SCT2a Slide 128



Recommended Design StrengthFor PARATECH Raker System – 45 deg

Raker Length

Height to Insertion


16 ft 11.0 ft 5000 lbs 15 10.5 ft 6400 14 10.0 ft 7800 13 9.0 ft 9200 12 & less 8.5 ft 10,600 lbs

System is made from 2 rakers spaced 8ft max. apart with X-bracing.

Rakers need to be attached to wall surface and restrained at ground.

If raker is mid-braced (each way), use 10,000 lbs.

SCT2a Slide 129



Recommended Design StrengthFor PARATECH Raker System – 60 deg

Raker Length

Height to Insertion


16 ft 13.8 ft 3500 lbs 15 13.0 ft 4500 14 12.0 ft 5500 13 11.25 ft 6500 12 10.4 ft 7500 11 ft 9.5 ft 10,000 lbs

2 rakers spaced 8ft max. apart with X-bracing Rakers need to be attached to wall surface, and

restrained at ground. If raker is mid-braced (each way) use 10,000 lb.

SCT2a Slide 130



Tilt-up Wall Bracing Spot Shores w/conn ea end

Can be used to brace reinforced concrete or masonry wall

Use Drill-in Anchors for connections to wall & floor slab.

Can act in Tension or Compression

SCT2a Slide 131


Structural Collapse Technician Training Tilt-up Wall - adjustable pipe brace

SCT2a Slide 132



Tieback Systems Used to keep wall from falling when too high for Rakers

Strongbacks - 4x4, 4x6, 2-2x6

Strongbacks go floor to floor

Tiebacks - rope, cable, chain

Extend tiebacks across bldg or tie to floor bms or columns

SCT2a Slide 133


Structural Collapse Technician Training Tiebacks used after Loma Prieta, 89EQ By S.E. & contractor

Rods connect to

floor beams

SCT2a Slide 134



Wood Apartments Stabilized by Rob Trost, House Mover

San Francisco 1989 - 36 bldgs as much as 24"out of plumb in 1st story - stabilize or demolish

SCT2a Slide 135



26 - three & four story bldgs leaning after Loma Prieta EQ

Needed bracing or a

collapse like this

could occur

SCT2a Slide 136


Structural Collapse Technician Training Wood Apartments Stabilized by Rob Trost, House Mover

Diagonal 6x8x20ft shores placed from cut in sidewalk behind curb up to 2nd floor to align with floor beams.

Door jambs were removed and diagonal 6x6 were added in garage openings.

SCT2a Slide 137



R Trost braced this in 2hr + Using 6x8 bearing on inside of curb

SCT2a Slide 138


Structural Collapse Technician Training R Trost - Details6x8 bearing on inside of curb up to 2nd floor

SCT2a Slide 139



After it was straightened

Bracing was designed by S.E. to keep sidewalk clear

Same building by Rob Trost

Similar bldg after being straightened

Note X braced cribbing

SCT2a Slide 140


Structural Collapse Technician Training Most Probable Shoring For Common Bldg Types Student Manual contains suggestions

for the following types of buildings: Light Frame URM - Heavy Wall TU - Heavy Wall C1 - Concrete Frame Heavy Floor PC2 - Precast Concrete

SCT2a Slide 141



Inspection of US&R Shoring Should be done at each Shift Change +

following any known loading change. Aftershocks, Winds, Secondary Explosion.

Properly proportioned Wood Shoring should be considered as a crude Load Cell.

What are the signs of Overload?Cupping of Wedges.Crushing of Header at Post.Splitting of Header at end of Overhang. Indicates about 1.5 to 2 times Design Load.These signs are not as pronounced when using

Southern Pine Timber.

SCT2a Slide 142



Signs of Overload

Crushing of Header by Post

+ Splitting of Header

Cupping of Wedges

SCT2a Slide 143



Inspection of US&R Shoring Overloading requires "Appropriate

Action" by StS Overloading could indicate:

More shores are neededThat structure is responding differently

than expected, and need to re-evaluate entire situation.

That something was wrong with the original design

SCT2a Slide 144



US&R Shoring Summary - 1 Shores - strong, light, portable Support as gently as possible Need slow, predictable failure mode.

Use wood posts with L/D = 25 or less Systems - positive connections & bracing

Start with Class 1 (1-dimensional) Spot Shores, then progress to

Class 2 (2-dimensional) Shores, and eventually upgrade to

Class 3 (3-dimensional) Systems Periodic Shoring Inspection is Essential

SCT2a Slide 145



US&R Shoring Summary - 2 Testing has been helpful – Part of StS2 Training

Raker Shores – What is Failure Mode? Laced Posts - What configurations are better?

Load at which initial "Wedge Cupping" occursDoes spaced Ply Bracing Work as well as 2x Diagonals

Double Tees – Paired like Laced PostsCan they perform as well as Laced Posts to 17 ft high

Cribbing – Explore ways other than friction to transfer of lateral forces.Observe just how much system deflects

What amount of friction is developed between Concrete Slabs and Wood Shoring? On level or sloped surfaces

SCT2a Slide 146



Review Key Learning Points - 1 What is Size and Type of Load that needs to

be supported?The weight of the supporting structure plus its

overload, or just its overloadBroken Structure or Rigid Structure

How much Shoring do you need?Should Shoring be similar to a Life Jacket? –

providing just enough lift to keep one afloatSome portion of the load can be (is being)

carried by the un-shored structure

SCT2a Slide 147



Review Key Learning Points - 2 What is the Capacity for the various types of

US&R Shoring Systems? How to configure US&R Shoring to ensure a

predictable & slow Failure Mode How to sequence the construction of US&R

shoring in order to Minimize RiskWhat are initial, short-term systemsWhat are more long-term systemsWhat are Class 1, 2, & 3 SystemsWhat is sequence in Multi-Story Shoring?

How and When to Inspect US&R Shoring

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