The implementation of a provision against progressive collapse /

# NBSIR 75-715 

# The Implementation of a 

# Provision 

# Against 

# Progressive Collapse

FelixY. Yokel,

### JamesH. PielertandAlvin R. 

### Schwab

CenterforBuildingTechnology Institute forAppliedTechnology National Bureau ofStandards Washington, D.C. 

### 20234

August 1975



### Prepared for Office ofPolicy

### Developmentand

### Research 

### Department of

### Housingand

### Urban

### Development Washington, 

### D.C. 

### 20410IMBSIR

### 75-715 

## THEIMPLEMENTATIONOFA

## PROVISION 

## AGAINST

## PROGRESSIVE

## COLLAPSE

Felix Y. Yokel, 

### James H. PielertandAlvin R. 

### Schwab

Center forBuildingTechnology Institute forAppliedTechnology National Bureau ofStandards Washington,

## D.C 20234

August 1975

Prepared for OfficeofPolicy

### Developmentand Research Department of

### HousingandUrban 

### Development Washington, D. C. 20410

U.S. 

## DEPARTMENTOF

## COMMERCE, RogersC.B. 

### Morton, Secretary 

### JamesA. Baker, III,

### UnderSecretary Dr. BetsyAncker-Johnson, AssistantSecretaryforScience

### andTechnology 

### NATIONALBUREAUOF

### STANDARDS, ErnestAmbler, ActingDirectordfewn,:? .RfliviA bfis'li©

\

### Table of 

### Contents Page 

### Abstract 11 1. 

### Introduction 1 2. 

### The 

### Criterion and Its 

### Interpretation 1 3. 

### Case 

### Histories 2 3

.1 

### General 2 3.2 

### The 

### FCE-Dillon System 2 3.3 

### The 

### Descon Concordia System 3 3.4 

### The 

### Rouse-Wates 

### System 3 3.5 The 

### Camel System.

. 4 3.6 

### The BSI 

### System 5 4. Some 

### Common 

### Characteristics of the

### Design Solutions 5 5. 

### Conclusions 6 6. 

### References 

# ..... 7

i

### THE 

### IMPLEMENTATION OF

### APROVISION

### AGAINST PROGRESSIVE COLLAPSE



### by • 

### ' «KSj3feY


### FelixY. 

### Yokel, 

### James H. 

### Pielert and

### Alvin R. 

### Schwab

. . . . ' J:.:h'-lrjc

.iv: .i.'

### M- fk'ti



### The 

### design solutions used

### by five U.S. 

### precast concrete 

### housing systems to 

### comply

### with a

### provision against 

### progressive collapse are 

### studied and compared. Some 

### common 

### characteristics of the 

### design solutions are identified. 

### KeyWords : 

### Building systems; 

### housing systems; 

### large-panel structures; 

### precast concrete construction; 

### progressive collapse; 

### structural design 

### structural joints.

ii1. 

### Introduction In 1969 the 

### Department of 

### Housing and 

### Urban 

### Development (HUD) 

### initiated 

### Operation Breakthrough, a 

### programdesigned to 

### encourage the 

### development and 

### introduction of 

### industrialization into the 

### housing industry in the 

### United States. 

### Under the 

### Breakthrough 

### program a 

### number of 

### housing systems 

### were selected, evaluated, and 

### constructed on 

### demonstration sites. The 

### National Bureau of Standards, on

### behalf of HUD, 

### drafted 

### criteria [1]-'- 

### whichwere used to 

### guide the 

### development and 

### subsequent 

### evaluation of these 

### housing systems. 

### These "Guide 

### Criteria" 

### contained a 

### provision against 

### progressive collapse under 

### catastrophic loading 

### which was 

### not 

### previously contained in any U.S. code or 

### standard (Progressive 

### collapse may be defined as a 

### chain 

### reaction of 

### failures 

### following damage to only a 

### relatively small 

### portion of a structure)

. This 

### report 

### discusses the 

### implementation of this 

### provision. 2. The 

### Criterion and its 

### Interpretation The 

### criterion against 

### progressive collapse used in 

### Operation Breakthrough is 

### quoted below:
o Re.quAJime.nt Ex.plo&'ioYid OK. othnn. c/xtoM

### trophic toadi, on anij onz. i,tofiLj 

### Zzvzl i>houJid 

### not 

### caoie pfLogK-U-itve. iitAiLcJiiJuxJi cotla.p6t 

### at otkeA ^eueXi. o CfUteAion: The. cAitetiion apptie.6 to baitding^ ifouA 6touted on. higheA.. 

### At a 

### load level o{, 

### one 

### dead

## +0.5 live, 

### the

### aaddental fiesnoval of, 

### any one o{, 

### the iotlowtng [load] 

### ^apponXing 

### 6tAacXuAal elejmenti 

### at one level, 

### should not cauie 

### colZapie of 

### the 6tM.ucXuAe on anotheJi level: a. tiMo 

### adjacent

### Mall paneZi 

### fomlng an exteAlofi con.neA b. one

### MolZ panel 

### tn a 

### location otheA

### than an exX.eAA.on. 

### conneA c. one 

### column on. 

### otheA 

### element of 

### the pnlmany 

### itnuctuAol 

### iuppont -i>y6tem. ThJj, cAAjteAlon Li 

### waived if 

### the 

### above-mentioned

### ^tnactuAal element on elements 

### one capable of n.Z6ij,ting 

### a pn.ti>i>an.e of 5 

### p6i (34.5 kPa)
, 

### applied 

### in the mo6t cnJjticat 

### manneAMitiUn one 6ton.y

### level to 

### one face of 

### the element and of 

### alt i>pace dividenA -iupponted by 

### the 

### element on. 

### attacked to it. oJz^t: KnalyiiM and/on. phyi>icjal 

### simulation oCommentany: 

### The 

### need fon thit, 

### nequinement i6 

### emphasized by

### several n.ecent 

### caXastAopheM

. 

### The collapse of 

### the Ronan Point 

### Kpantment BuJlding, London, 

### demonstnated one 

### sounce of 

### catastnophic loading, 

### namely a gas explosion. 

### The Tni.bu.nal 

### investigating the 

### cause of tka, 

### collapse [2] 

### pointed out tkaX. "the 

### problem of pn.ogne.ssive 

### collapse had not 

### been 

### consideAed by

### most 

### stnactuAal engineers 

### conceAned

### with 

### the 

### development of 

### tall systembailX. 

### blocks"

. 

### Systems 

### meeting thts n.equAAement

### would be 

### designed to 

### withstand local explosion. This 

### cnAXenlon is 

### conseAvative andwas 

### tentativelyadopted 

### in accordance 

### with the tnibunal's 

### recommendations. 

### The won.d "panel" is 

### used to 

### describe a

### portion of an

### interior or 

### exterior bearing 

### wall between tu)o 

### primoAy

### structural membeAs, or 

### between two 

### interiorwalls, or 

### between a corneA and 

### either an

### inteAlor

### wall or a

### primary

### structural membeA. This 

### criterionwas 

### written

### with gas 

### explosions inmind, but it was also 

### envisioned that other 

### abnormal loads (loads not 

### normally considered by designers)

### may occur and cause the 

### failure of a 

### primary 

### structural member. The 

### progression of 

### collapse 

### considered in this 

### criterion is in a

### vertical direction. 

### There are no 

### explicit 

### limitations on the 

### horizontal spread of ^Figures in

### brackets indicate 

### literature references.

1

### progressive collapse 

### within a 

### single story. The load 

### considered is 50 

### percent of the 

### design live load, 

### accounting for the low

### probability of the 

### coincidence of a 

### catastrophic load

### with full 

### design live load. The 

### criterion does not 

### require 

### consideration of the 

### debris 

### loading that the 

### collapse of part of the 

### structure could generate. The 

### criterionprovides the 

### option of 

### either 

### designing "strong" 

### members, 

### capable of 

### resisting the 5 

### psi (34.5 kPa) 

### pressure, or 

### providing an 

### "alternate path" of load support. In the 

### implementation of the 

### criterion the 

### assumption was 

### made that a

### wall panel can only be 

### considered "strong" if the 

### panel itself, as 

### well as the 

### lateral 

### supports 

### necessary to insure its 

### stability under the 

### stipulated

### minimum load of dead plus 0.5 live, 

### would survive 

### after the 5 psi (34,5 kPa) 

### pressure is applied. It is not the 

### intent of this 

### report to 

### discuss the 

### need for, or the 

### adequacy of, the 

### quoted criterion. 'Since the time the 

### criterionwas 

### proposed, the 

### matter of 

### progressive collapse has 

### been under 

### considerationby

### professional committees in the U.S., however, no 

### formal 

### recommendations have 

### been adopted by the 

### profession. 3. Case 

### Histories 3

.1 

### General Selected case 

### histories of 

### Operation Breakthrough systems are 

### described in 

### order to 

### illustrate specific 

### approaches 

### which

### were judged by

### designers to 

### satisfy the 

### stated criterion. It is 

### realized that the 

### design solutions 

### described do 

### not 

### necessarily represent the 

### only

### way in 

### which the 

### criteria could 

### have 

### been satisfied. 

### However the case 

### histories illustrate some of the 

### approaches that 

### other 

### designers might consider

### when faced

### with the 

### task of 

### increasing the 

### resistance of 

### buildings to 

### progressive collapse. The 

### general features of 

### these 

### systems 

### were previously described elsewhere [3], 

### although specific features 

### relating to 

### progressive collapse 

### have not 

### been discussed to the 

### extent 

### presented below. 3.2 The 

### FCE-Dillon System

. This 

### systemwas 

### developed in the U.S. and 

### adapted to 

### meet the 

### Breakthrough requirements. 

### A typical 

### portion of a 

### floor 

### plan is 

### shown in figure 1. The 

### structural components, as 

### numbered in 

### figure 1, are: precast, 

### hollow-core 

### bearingwalls (1) 

### typically 28 ft x 8 ft-7 1/2 in X 8 in (8.53 

### m x 2.63 

### mx 20.3 cm); 

### precast 

### prestressed floor 

### planks (2), 

### typically 32 ft X 8 ft X 6 in (9.75 

### mx 2.44

### m x 15.2 cm) and 22 ft-4 in x 8 ft x 4 in (6.81 

### m x 2.44 

### mX 10.1 cm); 8 in (20.3 cm) 

### thick

### balcony and 

### stairwell floor 

### panels (3), 

### preassembled kitchen and 

### utility (heart) 

### modules (4) 

### resting on 8 in (20.3 cm) 

### thick floor 

### panels of 

### typical 

### floor-plank dimensions, "double T" 

### exterior walls at the end of the 

### stairwells (5), 43 ft-7 in 

### high X 7 ft-7 in

### wide (13.28 

### mx 2.31 m) ; and 

### elevator-shaft units not 

### shown in'the 

### portion of the 

### floor 

### plan in 

### figure 1. 

### Clear spans 

### between bearing walls are 22 ft (6.71 m) and 31 ft-8 in (9.65 m) .



### A typical 

### hollow-core bearing

### wall section and floor to 

### wall joint detail are 

### shown in figure 2. 

### After erection and 

### appropriate shoring, 

### vertical reinforcement is 

### inserted in some of the 

### hollow cores, and 

### horizontal reinforcement is 

### placed on top of the 

### floor planks. Subsequently, the 

### reinforced

### wall cores are 

### filled

### with concrete and a cast in

### place concrete topping is 

### placed on the floor 

### planks to a total floor 

### thickness of 8 in (20.3 cm). The 

### horizontal and 

### vertical reinforcement is 

### continuous through 

### interior joints, and 

### horizontal bars are 

### anchored in the 

### exterior

### wall joints to 

### develop their full 

### tensile strength. 

### There are 

### reinforcement ties 

### between the 

### floor slabs of the 

### heart 

### modules and 

### adjacent slabs. 

### All 

### bearingwalls are 

### designed as 

### "strong" 

### members and thus are 

### capable of 

### resisting the 

### stipulated 5 psi (34.5 kPa) pressure. This 

### approach is not 

### difficult to 

### implement since the 

### unsupported (floor to ceiling) 

### height is 

### only 8 ft (2.44 m)

. However, tha floor 

### planels 

### have a

### much larger 

### unsupported span and can not be 

### economically designed to 

### resist an 

### upward or 

### downward 

### pressure of 5 psi (34.5 kPa)

. In the case of a space 

### enclosed by two 

### interior

### bearingwalls even floor 

### panels on two 

### consecutive levels 

### between these 

### walls could fail 

### without depriving the 

### walls of their 

### lateral support, 

### which in this case 

### would be 

### provided by floor 

### panels on the 

### other side of the walls. 

### Aproblem, 

### however, 

### arises 

### when one or 

### both of the 

### bearing walls are 

### exterior walls, since the loss of a 

### floor 

### panel 

### would deprive these 

### walls of 

### lateral support, 

### causing a 

### stability failure. This 

### problem is solved by

### providing 

### specially-strengthened partitions. 

### A typical 

### detail of such a 

### partition is shown in figure 3. The effect of the 

### partition is 

### illustrated in 

### figure 4. 

### While the 

### partition in the space 

### withinwhich the 5 

### psi (34.5 kPa) 

### pressure is 

### applied is not ex- 

### pected to survive, the 

### partitions in the 

### stories 

### above and 

### below this space 

### provide 

### reaction forces, thus 

### reducing the 

### effective span of the 

### floor and 

### ceiling panels. The 

### reaction force 

### transfered to the 

### partition is 

### resisted by one or two 

### successive floor (ceiling) 

### panels or 

### transfered 

### directly to the foundation. If the 5 

### psi (34.5 kPa) 

### pressure is 

### applied in the 

### space 

### below the roof, the roof 

### panel 

### would fail. However, a roof 

### panel failure 

### would not 

### trigger a 

### progressive collapse. Since the 

### specially-designed partitions are 

### located

### where partitions are 

### required in any case, the cost 

### increase does not 

### exceed the 

### difference in cost 

### between the 

### special 

### partitions and the 

### non-loadbearing drywall 

### partitions used in 

### other 

### parts of the 

### housing unit. 3.3 The 

### Descon Concordia System The 

### Descon Concordia System is a 

### large-panel concrete 

### system that 

### was 

### developed in Canada. The 

### structural components of the 

### system are 

### shown in 

### figure 5, and 

### consist of: 

### precast 

### concrete 

### wall panels (1), 

### typically 30 ft x 8 ft x 6 1/2 in (9.14 

### mx 2.44 

### m x 16.5 cm) 

### with 1 1/2 in (3.8 cm) 

### insulation and a 3 in (7.6 cm) 

### thick 

### concrete cladding 

### panel added for 

### exterior walls; 

### precast 

### prestressed floor 

### panels (2), 

### typically 22 ft x 10 ft x 6 1/2 in (6.71 

### mX 3.05 

### mx 16.5 cm); two 

### panelized longitudinal shear

### walls not 

### shown in 

### figure 5, 

### located on 

### opposite sides of the corridor, 18 ft-1 in (5.51 m) long and 10 in (25.4 cm) thick; and 

### non-loadbearing

### windowpanels (3)

. 

### Clear floor spans 

### between transverse 

### bearing

### walls are 21 ft-5 in (6.53 m) .

All 

### panels are 

### connected by

### bolted connections 

### which are 

### located as 

### shown in 

### figure 5 (A & B) 

### Typical bolted 

### connections are 

### shown in 

### figure 6. 

### All 

### connections are 

### capable of trans

### mitting tensile and shear forces. As in the case of the 

### Dillon System, all 

### bearingwalls are 

### designed as "strong" walls. Again, loss of the 

### floor and 

### ceiling in an 

### interior unit 

### would not cause 

### collapse of the 

### bearing

### walls 

### whichwould receive lateral support 

### from floor 

### panels on the 

### other side. 

### However, an 

### exterior 

### bearing

### wall could 

### collapse after losing the 

### lateral support 

### from a floor. Thus 

### special "strong" floor 

### panels 

### were provided. The 

### location of these 

### panels is 

### shown in figure 5. 

### Instead of 

### strengthening an 

### entire panel, each of the strong 

### panels was 

### provided

### with two 

### heavily-reinforced bands, as 

### shown in 

### figure 7. 

### These bands 

### were designed to 

### survive the 5 psi (34.5 kPa) 

### pressure

### while the rest of the 

### panels 

### would break away at a lower pressure. 

### After an 

### explosion these 

### strong bands 

### together

### with other 

### remaining panels, such as 

### balcony and 

### corridor floor panels, 

### would provide lateral support to the 

### exterior wall. 3.4 The 

### Rouse-Wates System This 

### system is an 

### adaptation of the 

### EuropeanWates system. 

### Figure 8 is a 

### portion of a 

### typical floor plan. The 

### structural elements are: 

### "strong" 

### bearing wall panels (1); interior 

### bearing wall panels (2) ; 

### nonbearing exterior

### wall panels (3) ; 

### corridor

### wall panels (4) ;



### regular floor 

### panels (5); 

### "strong" floor 

### panels (6); and 

### corridor floor 

### panels (7). 

### Typical panel sizes for the floor 

### plan in figure 8 are 19 ft-9 in x 7 ft-5 in x 8 in (6.02 

### m x 2.26 

### mX 20.3 cm) for floor panels, and 22 ft x 8 ft x 7 in (6.71 

### m x 2.44 

### m x 17.8 cm) for 

### bearing

### wall panels. 

### Clear floor spans 

### between transverse 

### bearingwalls are 19 ft-5 in (5.92 m) .



### Figure 9 shows a 

### typical cast in

### place 

### horizontal joint at an 

### interior 

### bearing

### wall panel. The 

### joint 

### provides 

### reinforcement ties 

### between adjacent floor 

### elements and 

### between floor 

### elements and their 

### supporting 

### bearing walls. 

### There are no 

### vertical ties 

### between successive 

### bearing-wall panels. 

### Vertical joints are 

### unreinforced .

3

### Compliance 

### with the criterion, as 

### documented by the 

### designers, is by a 

### combination of 

### "strong" 

### bearing

### walls and 

### alternate paths of load support. As 

### shown in 

### figure 8, two 

### parallel strong 

### bearingwalls (1) 

### enclose the spaces next to the 

### exterior walls. As in the 

### previously-discussed cases, 

### strong floor 

### panels (6) 

### must also be 

### provided to insure 

### lateral sup

### port for the 

### strong 

### exterior walls. The 

### interior 

### walls and floors are not 

### designed to 

### resist 5 

### psi (34.5 kPa)

. If any 

### interior 

### bearingwall is removed, the floor 

### supported by this 

### wall 

### will fail, and the 

### wall above the 

### floor is 

### designed to act as a 

### cantilever girder 

### connected to the 

### corridor wall. The 

### longitudinal reinforcement in the 

### joint in 

### figure 9 is 

### anchored so that 

### tensile forces at the top of the 

### suspended

### wall can be 

### transmitted to the 

### corridor slab. 

### According to the 

### designers, the 

### cantilevermoment 

### would be 

### resisted by the 

### corridor slabs at the top and 

### bottom of the 

### suspended wall. The 

### vertical joint 

### between the 

### suspended

### wall and the 

### corridor 

### wall 

### would resist the 

### cantilever shear. The 

### Rouse-Wates 

### systemwas also 

### designed to 

### meet the 

### following 

### prescriptive provisions of 

### AddendumNo. 1 (1970) to the 

### British Standard Code of 

### Practice CP116 [3]: 1. 

### horizontal wall to floor 

### joints 

### capable of 

### resisting 1700 lb 

### per ft (2.48 kN/m) at the 

### bottom of the wall, 2. an 

### uninterrupted peripheral tie at each floor level to resist a force of 9000 lb (40.03 kN) ,

3. 

### internal ties, 

### anchored to the 

### peripheral tie, 

### capable of 

### resisting a force of 1700 lb 

### per foot (2.48 kN/m) in the 

### longitudinal 

### direction and 850 lb 

### per foot (1.24 kN/m) 

### acting over 

### half a 

### bay

### width in the 

### transverse 

### direction (the bars in the 

### transverse 

### direction

### were concentrated in the 

### horizontal joints 

### between transverse 

### bearing walls) .

3.5 The 

### Camci 

### System This 

### system is an 

### adaptation of the 

### European Tracoba System. 

### Figure 10 shows a 

### portion of a 

### typical 

### floor plan. 

### Typical 

### connection detail is 

### shown in 

### figure 11. 

### The

### main structural components are: 

### transverse exterior

### wall panels (1), 11 in (27.9 cm) thick, 

### including an 

### insulating layer

### between a 6-in (15.2 cm) 

### thick 

### interior concrete 

### panel and a 3 in (7.6 cm) 

### thick 

### exterior concrete panel; 

### transverse interior

### wall panels (2), 

### typically 24 ft-10 in X 8 ft X 6 in (7.57 

### m x 2.44 

### mx 15.2 cm); 6 in (15.2 cm) 

### thick 

### longitudinal corridor

### wall panels (3); 10 in (25.4 cm) 

### thick 

### facade (windowwall) 

### panels (4); floor 

### panels (5), 

### typically 25 ft-1 in x 12 ft-1 in x 5 1/2 in (7.65 

### m x 3.68 

### m x 14.0 cm); roof parapets, not 

### shown in 

### figure 10, 10 in (25.4 cm) or 11 in (27.9 cm) thick and 

### extending 7 ft-3 in (2.21 m) 

### above the roof level; and 

### externally-attached balcony units (6). 

### Clear floor spans 

### between transverse 

### bearingwalls range 

### from 10 ft (3.05 m) to 12 ft (3.66 m) .

It canbe seen 

### from figure 11 that 

### continuous 

### reinforcement (anchored 

### hairpin reinforcement) 

### extends through all the 

### horizontal and 

### vertical 

### cast-in-place joints. 

### There are also 

### mechanical connectors 

### providing

### vertical continuity

### between all the 

### transverse walls, and 

### between all roof 

### parapets and their 

### supporting walls. 

### Compliance 

### with the 

### progressive collapse 

### criterion is 

### entirely by 

### alternate paths of load support. Thus 

### removal of any one 

### bearing

### wall panel or any two 

### adjacent 

### wall panels at an 

### exterior corner 

### shouldnot cause 

### progressive collapse. The 

### most 

### critical case is 

### illustrated by figure 12 and 

### occurs in the 

### story

### below the top story. One 

### gable 

### wall and one facade 

### wall are removed. It is 

### assumed that floor 

### EFGH is left in 

### place and has to 

### support 1/2 the live load. The slab is 

### supported 

### by

### bearing walls along sides EF and GF. Side EH is 

### suspended from

### panel

### ADHKby the 

### reinforced joint (see 

### figure 11). 

### Wall panels 

### ADHE and 

### DCGH are 

### connected to 

### parapet panels 

### LKDAand KJID by

### vertical connectors and by- 

### continuous 

### vertical reinforcement in 

### joint HDK, 

### which also 

### connects the two 

### wall panels to each other. The 

### suspended

### wall panels are also 

### connected to 

### adjacent 

### panels through

### vertical 

### joints GC and EA. 

### Panel ADHE, as 

### well as 

### panel 

### DCGH together 

### with parapet KJID, act as

### cantilever girders. Shear is 

### resisted by the 

### vertical joints and by 

### parapet 

### panel KJID, and the floor and roof slabs at 

### joints EF, AB, GF and CB assist in 

### resisting the 

### moments by 

### providing

### moment-resisting couples. 

### Similar less 

### critical 

### alternate paths of load 

### support canbe 

### shown to exist 

### whenbearing

### wall panels at lower levels are removed. 3.6 The BSI 

### System This 

### system is an 

### adaptation of the 

### European Balency-Schuhl system. 

### A

### portion of a 

### typical floor 

### plan is 

### shown in figure 13. 

### Figure 14 shows 

### typical 

### joint detail. The

### main structural components are: 

### exterior

### wall panels (1), 7 1/2 in (19.1 cm) thick; 

### interior

### wall panels (2) 

### including corridor walls, 

### with a

### maximum size of 21 ft x 8 ft X 6 in (6.40 

### m X 2.44

### mx 15.2 cm); "strong" 

### interior

### wall panels (3), 6 in (15.2 cm) thick; and floor 

### panels (4) 

### with a

### maximum size of 21 ft-6 in x 12 ft-2 in x 6 in (6.55 

### mx 3.71

### mX 15.2 cm). Clear 

### floor spans 

### between transverse 

### bearingwalls range from 11 ft (3.35 m) to 12 ft (3.66 m) .

The 

### vertical joints 

### shown in 

### figure 14 

### provide continuous (interlocking) 

### reinforcement in the 

### horizontal, as 

### well as the 

### vertical direction. 

### Horizontal joints 

### provide ties 

### between adjacent floor 

### elements and

### between floor 

### elements and the top of 

### supporting 

### bearing walls. 

### Vertical ties 

### between successive 

### bearing walls are only 

### provided in the end walls. 

### Compliance

### with the 

### progressive collapse 

### criterion is 

### generallyby 

### alternate paths of load support, except for some 

### isolated interior

### wall panels 

### whichwere designed as 

### strong panels. The 

### alternate paths are

### made possible by the 

### continuity of the 

### vertical joints. For example, if 

### panel FllO in figure 13 is removed, the 

### panel above 

### will be 

### supported by panels F113 and FlOO, a 

### panel 

### enclosing an 

### exterior balcony. The 

### continuous 

### vertical joints 

### would also 

### permit 

### cantilever support of larger 

### portions of the 

### building in a

### manner similar to that 

### discussed for the Camci system. On the 

### other hand, 

### panel RlOl 

### which does not 

### have this type of 

### support 

### from

### vertical joints, was 

### designed as a "strong" panel. 4. Some 

### Common 

### Characteristics of the 

### Design Solutions The systems 

### described in 

### Section 3 can be 

### categorized as 

### long-span systems and shortspan systems. The 

### long-span systems 

### include 

### FCE-Dillon, 

### Descon Concordia and 

### Rouse-Wates. Their clear floor spans 

### betweenbearingwalls range 

### from 19 ft-5 in (5.92 m) to 31 ft-8 in (9.65 m) and the spaces 

### between transverse 

### bearingwalls are 

### sub-divided by 

### non-loadbearing partitions. The 

### short-span systems are 

### Camci and BSI, 

### with floor spans 

### ranging 

### from 10 ft (3.05 m) to 12 ft (3.66 m) .



### All 

### long-span systems 

### relied on "strong" 

### bearing walls to 

### comply

### with the 

### progressive collapse criterion. The 

### "strong" 

### bearingwalls always 

### include the end

### walls and the cross 

### walls following the endwalls. The systems 

### have the 

### common

### problem of 

### providing lateral support to the end walls. This 

### problemwas solved by the three systems in three 

### different ways: FCE 

### Dillon used 

### specially designed 

### partitions to 

### provide 

### intermediate support to the floors; 

### Descon-Concordia used floor 

### panels 

### with strong bands; and 

### Rouse-Wates used 

### strong floor panels .

No 

### specific 

### common 

### joint-reinforcement requirements canbe 

### identified for the 

### long-span systems 

### using strong 

### bearingwalls, 

### except those 

### arising from the 

### requirement that 

### connections 

### between strong

### members 

### must resist the 

### reaction forces caused 

### by the 

### specified 

### design pressure of 5 

### psi (34.5 kPa)

. In the case of the 

### Rouse-Wates system, 

### where an 

### alternate 

### path of load 

### support 

### was intended for 

### interior 

### cross-wall panels, the 

### designers used 

### continuous 

### horizontal 

### reinforcement 

### between the floor slabs 

### resting on the 

### transverse 

### bearing walls and the 

### corridor floor slab, 

### between the floor slabs 

### resting on

### both sides of a 

### transverse 

### bearing wall, and 

### between the 

### transverse 

### bearing

### walls and the floor slabs above. The 

### designers also 

### relied on 

### longitudinal reinforcement on top of 

### transverse 

### bearingwalls, and 

### particularly, on 

### anchorage of this 

### reinforcement into the 

### corridor slab.

5The 

### short-span systems 

### relied 

### primarily on 

### alternate paths of load support. The 

### Camci 

### system relied on a roof 

### parapet to 

### support the 

### uppermost story. The 

### following 

### joint 

### reinforcement was 

### needed in

### both systems to 

### comply

### with the 

### progressive collapse criterion: (1) the 

### vertical joints 

### between adjacent and 

### intersecting 

### wall panels 

### were the 

### most critical. 

### These had to be 

### reinforced 

### horizontally to 

### transmit 

### horizontal 

### tensile forces 

### between adjacent 

### wall panels, and

### vertically to 

### resist tensile forces 

### between successive stories; (2) the 

### horizontal joints 

### between the 

### corridor floor slabs and slabs on the 

### other side of the 

### corridor walls 

### were also critical. 

### Reinforcement ties 

### between the 

### corridor floor slabs and the 

### adjacent floor slabs and

### between the 

### corridor and 

### transverse 

### walls and the 

### corridor floor slabs 

### insured that the 

### corridor slabs 

### could be 

### engaged in 

### resisting

### moments transmitted by 

### cantilevering transverse 

### bearing walls; (3) the 

### horizontal joints 

### between transverse 

### bearing

### walls and 

### floor 

### panels 

### resting on 

### both sides of these 

### walls 

### were somewhat less critical, but in all cases 

### reinforcement similar to that in the 

### horizontal joints at the 

### corridor floor slabs 

### was needed; (4) 

### vertical reinforcement ties 

### between successive 

### bearing

### walls panels, in 

### addition to those 

### provided by the 

### continuous 

### vertical reinforcement bars 

### within the 

### vertical joints, 

### were only 

### necessary in the 

### upper story of the 

### Camci system

### where the roof 

### parapet was engaged to 

### support the 

### uppermost story. 

### However it can be 

### shown that such 

### reinforcement 

### would substantially increase the load 

### resistance of 

### suspended 

### bearing walls in 

### stories 

### below the top story. 5. 

### Conclusions The 

### following conclusions are 

### drawn from the 

### study of the 

### design solutions 

### discussed in this 

### report .

1. The 

### systems 

### with clear spans 

### between transverse 

### bearing walls greater than 19 ft (5.79 m) 

### had to use 

### "strong" 

### transverse 

### bearing

### walls at least for the end 

### walls and the 

### transverse 

### walls next to the end walls. In all cases, 

### special 

### provisions had to be 

### made to 

### provide lateral support to the end walls.
2. The 

### systems 

### with clear spans of 12 ft (3.66 m) or less 

### relied 

### principally on an 

### alternate paths of load support. 3. In 

### short-span systems 

### using an 

### alternate path of load 

### support the 

### following 

### joint rein

### forcement ties 

### were the 

### most critical: 

### horizontal ties in the 

### vertical joints 

### between adjacent or 

### intersecting 

### bearing walls; 

### continuous 

### vertical ties 

### throughout the 

### building in the same joints; 

### transverse 

### horizontal ties 

### between corridor floor 

### panels and 

### adjoining floor panels; and ties 

### between transverse walls and 

### corridor 

### walls and 

### between transverse walls and 

### corridor floor panels. The 

### alternate

### mode of load 

### support was also 

### assisted by 

### longitudinal 

### horizontal ties 

### between adjoining floor 

### panels on 

### either side of 

### transverse 

### bearingwalls, ties 

### between transverse

### bearingwalls and 

### connecting floor panels, and

### vertical ties 

### between successive transverse 

### bearing

### wall panels. The 

### preceeding conclusions are 

### subject to the 

### following 

### qualifications: 1. The 

### criterion states 

### certain design conditions but does not cover the 

### entire 

### spectrum of 

### possible causes of 

### progressive collapse. For instance; a gas 

### explosion

### may remove 

### more than the 

### specified number of panels; debris load

### may cause 

### progressive collapse; or 

### collapse 

### may

### propagate in the 

### horizontal direction. 

### There is, as yet, no 

### professional consensus as to

### which cases 

### should be 

### included in, or 

### excluded from, 

### consideration. 2.. 

### Provisions fair 

### continuity of 

### joints and

### miscellaneous ties, 

### similar to those listed in 

### Section 3.4, 

### may 

### eventuallybe 

### Imposed in 

### addition to the 

### rational design conditions 

### required by the criterion. Such

### prescriptive code 

### provisions could 

### change the 

### characteristics of 

### design solutions. 3. The 

### sample of five 

### systems 

### considered in this 

### report is not 

### very large, and the 

### design 

### solutions do not 

### necessarily represent the only

### way in

### which these 

### systems could have 

### complied

### with the criterion.

66. 

### References [1] The 

### Building 

### Research

### Division Team, 

### Guide 

### Criteria for the 

### Evaluation of 

### Operation Breakthrough

### Housing Systems, 

### Accession Numbers PB-212055, 212056, 212058, 

### National Technical Information Service (Springfield, Va. , 

### December 1970). [2] 

### Ministry of 

### Housing and 

### Local Government, 

### Report of the 

### Inquiry into the 

### Collapse of Flats at 

### Ronan Point, 

### Canning Town, 

### Her

### Majesty's Stationary Office (London, U.K., 1968), [3] 

### Department of 

### Housing and

### Urban Development^

### Design and 

### Development of 

### Housing Systems for 

### Operation Breakthrough, U.S. 

### Government 

### Printing Office, (Washington, D.C., 1973). [4] 

### British Standards Institution, 

### "British 

### Standard Code of 

### Practice for 

### Large Panel Structures, 

### AddendumNo. 1 (1970) to CP116, 

### The 

### Structural Use of 

### Precast 

### Concrete (London, U.K. , 1970) .

USCOMM-NBS-OC 71. Hollow-core bearingwalls

2. Precast Prestressed Floor Planks 3. Precast Stairwell and Balcony Panels 4. Heart Modules 5. Double "T" Exterior Panels



### Figure 1 

### Typical 

### Portion

## ofa 

### Floor Flan 

### for the 

## FCE Dillon 

### System#4OWLS. 2-0" X?-0"

### @24"

4 X4

-W2.9 XW2.9 

### ^1

-DOWELS TYPICALEXTERIORWALL-TOFLOORJOINT

, , HOLLOWCORE J- iiM' T

# —

.

# — —

'

T \ \ 4X4

-W2.9 XW2.9 1 #4OWLSX4-0"

### @24"

#4 X4-0"

### @ 18" CAST-IN-PLACECONCRETE

I

### —; : _ ~ 4- Q 

# —

TYPICALINTERIORWALL-TO-ROORJOINT POSITIONINGDOWEL LIFTINGHOOK

PORTION HORIZONTALSECTIONOFTYPICALHOLLOW COREWALLPANEL



### Figure 2 

### Typical 

### Hollow Cove Wall 

### Panel 

## and Floor to 

### Wall 

### Joint Details 

## ofFCE - 

### Dillon 

### System

\

### CAST IN

### PLACE 

### TOPPING 

### PRECAST 

### PRESTRESSED 

### PLANK



### Figure S 

### Typiaal Detail 

## of Specially

## DesignedPartition - 

## FCE Dillon 

### System

## STRONG

PARTITION 

## FLOOR

: t 

## EXPLOSION f



### I

## REACTIONBY PARTITION



## REACTIONBY 

### PARTITION 

## END 

## WALL



# FTTTTTTT 

# MMM

# M

Figure 4 

### Effect 

## of Specially 

## DesignedPartition 

## FCE Dillon 

### System

\1. Precast Concrete Wall Panels 2. Precast Concrete Floor Panels 3. Window Panels A. Bolted Floor-Diaphragm Connections



### Figuve 5 

### Structural Components 

## of the 

### Desoon 

### Conaordia 

### System1, FLOORPANEL

2 EMBEDDED INSERT 3 CONNECTORPLATE 4 FRICTIONBOLTS I BEARINGWALLPANEL 2. FLOOR PANEL 3. WALL INSERT-TOP 4. WALL INSERT-BOTTOM 5. METAL SHIMS 6. FLOOR INSERT 7. CONNECTIONMAKE-UPPIECES 8. FRICTIONBOLTS CONNECTIONA FLOORTOFLOOR CONNECTION B

WALLTOFLOOR 

### Figure 6 

### Typical 

### Panel 

### Connections 

### forDescon Concordia 

### System

6 l/2'l5l/< 2'-8" 5'

### -4"

9" 9" ReinforcedBand 2'-8"

Prestressing Stand 

### 4*7 Bot 

### 6*7 Top

•<7 / '* 

# 7^ ^*'4(S>24"0.i


### r ofReinforcedBand ft Floor Panel


### Figure 7 

### Section Through. 

### Strong Floor Panel 

## ofDesoon 

### Concordia 

### System

]

### Figure 8 

### Portion

## ofFloor Plan

## ofRouse-Wates System

1. Floor Panel 2. Cast in Place Concrete Joint 3. Transverse Joint Reinforcement 4. Longitudinal Joint Reinforcement 5. Lifting/Leveling Bolt 6. Leveling Cone 7. Precast Concrete Wall 8. Grout Bed 

### Figure 9 

### Typical 

### Cast-in-Place 

### Horizontal 

### Joint 

## ofRouse Wates 

### System1. Transverse End Wall Panel 2. Transverse Interior Wall Panel 3. CorridorWall Panel A. Facade Panels

5. Floor Panels 6. BalconyUnits



# ©

-© Figure 10 

### Portion

## ofTypical 

### Floor Plan 

## of Camci 

### System

\I 1/2- 11/2"

5I/?

TYPICALVERTICALJOINT

=1/4" 4l/2'i

EXTWAU. PANEL

TYPICALINTERIORHORIZONTALJOINT TYPICALEXTERIORHORIZONTALJOINT



### Figure 11 

### Typical 

### ConnectionDetails 

## of Camci 

### System

### Figure 12 

### Camoi 

### System - 

### Critical 

### Condition 

## for Progressive Collapse

### Figure 13 

### Portion

## of a 

### Typical 

### Floor Plan 

## of the 

## BSI System

### Figure 14 

### Typical 

### Joint 

### Details for 

### BSI SystemNBS-n4A (REV. 7-73) U.S. DEPT. OFCOMM. 

### BIBLIOGRAPHIC

### DATA SHEET 1.

### PUBLICATIONOR

### REPORTNO. 

### NBSIR 

### 75-715 2. Gov'tAccession

No. 3. Recipient'sAccessionNo.
4.

### TITLE

### ANDSUBTITLE 

### The 

### Implementation of 

### a 

### ProvisionAgainst 

### Progressive Collapse 5. PublicationDate
6. Performing OrganizationCode

7.

### AUTHOR(S) 

### Felix Y. 

### Yokel, 

### James H. 

### Pielpri- 

### anH 

### Al^Hn R <^nh,.T=,h 8. Performing Organ. ReportNo.



### NBSIR 75-715 9.

### PERFORMINGORGANIZATION

### NAMEANDADDRESS 

### NATIONAL

### BUREAUOF

### STANDARDS 

### DEPARTMENTOF

### COMMERCE WASHINGTON, D.C. 20234 10. Project/Task/Work UnitNo. 11. Contract/GrantNo.

12. Sponsoring Organization

### Name andCompleteAddress (Street, City, State, ZIP) 

### Department of 

### Housing and

### UrbanDevelopment 451 

### 7th 

### Street, S. 

### W. 

### Washington, D. C. 

### 20410 13. Type of Report 8c Period Covered
14. SponsoringAgencyCode 15.

### SUPPLEMENTARYNOTES

16.

### ABSTRACT (A 200-wordorless factualsunmaryolmostsi^iticant information. Ifdocument includes a significant bibliographyor literature survey, mention ithere.) 

### The 

### design solutions used

### by five U.S. 

### precast concrete 

### housing systems to 

### comply 

### with a 

### provision against 

### progressive collapse are 

### studied and compared. Some 

### common 

### characteristics of 

### the 

### design solutions are 

### identified.

17.

### KEY

### WORDS (six to twelve entries; alphabetical order; capitalizeonly the first letterof the firstkeywordunless aproper name; separatedbysemicolons) 

### Building systems; 

### housing systems; 

### large-panel structures; 

### precast concrete 

### construction 

### progressive collapse; 

### structural design; 

### structural joints. 18. 

### AVAILABILITY [X] Unlimited

I !ForOfficial Distribution. DoNotRelease toNTIS

I IOrderFromSup. of

### Doc, U.S. Government PrintingOffice Washington, D.C. 20402, SD Cat. No.

## CU

IX! OrderFromNational Technical InformationService (NTIS) Springfield, Virginia 22151 19. 

### SECURITY

### CLASS

(THIS

### REPORT) 

### UNCLASSIFIED 20. 

### SECURITY

### CLASS (THIS

### PAGE) 

### UNCLASSIFIED 21.NO. 

### OF

### PAGES 

## 23 22. Price 

## $3.25 USCOMM.DC 29042-P74ij " ,>•.• ,-.7 r.iA

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»& ,-J 'v,v.

'.VK.'^l" ;-»;n")-*t'

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