UNIVERSITI PUTRA MALAYSIA

STRUCTURAL BEHAVIOUR OF INTERLOCKING HOLLOW BLOCK PANEL WITH STIFFENER SUBJECTED TO AXIAL AND ECCENTRIC

LOAD

FARES A. SHEHAB.

FK 2005 8

STRUCTURAL BEHAVIOUR OF INTERLOCKING HOLLOW BLOCK PANEL WITH STIFFENER SUBJECTED TO AXIAL AND ECCENTRIC LOAD

BY

FARES A. SHEHAB

Thesis Submitted to the School of Graduate Studies, Universiti Putra Malaysia, In Partial Fulfillment the Requirement for the Degree Of Master Of Science

October 2005

Dedicated To My Parents, Brother and Sister

Abstract of thesis presented to the Senate of Univerisiti Putra Malaysia in fulfilment of the requirement for the degree of Master of Science

STRUCTURAL BEHAVIOUR OF INTERLOCKING HOLLOW BLOCK PANEL WITH STIFFENER SUBJECTED TO AXIAL AND ECCENTRIC

LOAD

FARES A. SHEHAB

October 2005

Chairman: Associate Professor Waleed A. M. Thanoon, PhD

Faculty: Engineering

The search for more rapid construction that need ordinary labor has led to the

development of interlocking masonry system in which the walls can be assembled

without using any mortar layer. The assembled hollow blocks in the wall provide

continuous hollow voids, which can be used to host stiffeners in vertical and

horizontal directions to enhance the integrity of the wall. However the effects of

reinforced concrete stiffeners on the structural response of the interlocking walls are

still not known and require further investigation.

This research is mainly focused on the structural behavior of interlocking hollow

block walls with stiffener constructed using PUTRA interlocking hollow block under

axial and eccentric vertical load.

Experimental program includes testing of individual block units, interlocking prism

and full scale interlocking walls. Since the compressive capacity of a wall is defined

in terms of compressive strength of the block unit used to construct the wall, the

compressive strength of different individual block unit was evaluated by testing 40

iii

block units for each type of block used to assemble the wall stretcher ,half and comer

block units.

Furthermore three course grouted prisms were tested and compared with un-grouted

prisms to explore the effect of grout on prism strength; these results were compared

with results presented by other researchers.

Five wall specimens of 1.2 m width and 3.0 m height were tested under the effect of

axial and eccentric vertical loads considering different eccentricity of 40 and 55 mm.

The research aims to investigate the effect of two different stiffeners layout on their

structural response compared to the walls without stiffener highlighting the

difference between interlocking walls with stiffener and conventional bonded

masonry walls using mortar layers. In the first layout, the reinforced concrete (R.C.)

stiffeners were located at the perimeter of wall, while in the second layout the

stiffeners were located at wall perimeter as well as horizontal stiffeners at mid height

of wall. The structural responses of tested panels were monitored in terms of wall

efficiency, deformation characteristics strain distribution reduction in wall capacity

due to effect of eccentric load cracking and failure mode.

The testing results show that the presence of stiffeners has improved the behavior of

tested panels by increasing the load carrying capacity of stiffened panels by 15% to

30% compared to un-stiffened specimens. Furthermore the horizontal stiffener

located at mid height of wall plays important roles in the capacity of wall and its

failure mode.

Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi keperluan untuk memperoleh ijazah Master Sains

KELAKUAN BERSTRUKTUR PANEL BLOK BERONGGA KAIT PANCA TERKAKU DI BAWAH BEBAN PAKSI DAN EKSENTRIK

Oleh

FARES A. SHEHAB

October 2005

Pengerusi: Professor Madya Waleed A. Thanoon, PhD

Fakulti: Kejuruteraan - --- --- -* - . .

Pencarian ke arah pembinaan lebih pantas yang bergantung pada kerja tangan yang

berkurangan telah menghasilkan pembinaan sistem masonri kait panca yang

melibatkan pemasangan dinding tanpa menggunakan sebarang lapisan mortar. Blok

geronggang yang terpasang pada dinding menyediakan ruang kosong berongga yang

berterusan yang dapat digunakan sebagai tempat pengikat kestabilan (pengkaku) arah

menegak dan melintang untuk menarnbah kestabilan dan integtiti dinding. Walau

bagaimanapun kesan pengkaku konkrit diperkuat terhadap gerak balas struktur

dinding kait panca masih tidak diketahui dan memerlukan penyiasatan lanjut.

Penyelidikan ini terutamanya berfokus pada tingkah laku struktur dinding blok

berongga kait panca yang dibina dengan menggunakan blok berongga kait panca

Putra di bawah beban tegak paksi eksentrik.

Program eksperimen termasuk pengujian unit blok individu prisma kait panca dan

dinding kait panca skala penuh. Oleh kerana keupayaan kompresif sebuah dinding itu

didefinisikan dari segi kekuatan kompresif unit blok yang digunakan untuk membina

dinding, kekuatan kompresif unit blok individu yang berlainan telah dinilai dengan

cara menguji 40 unit blok bagi setiap jenis blok yang digunakan bagi memasang

dinding iatu unit blok stretcher, corner dan half.

Seterusnya tiga prisma carnpuran cair diuji dan disbanding dengan prisma bukan

campuran cair untuk meneroka kesan grot terhadap kekuatan prisma. Semua

keputusan ini dibandingkan dengan keputusan yang diperoleh daripada penyelidik

lain.

Lima spesimen dinding berukuran 1.20m lebar dan 3.00m tinggi telah diuji di bawah

kesan beban paksi menegak dan eksentrik dengan mengambil kira keessentrikan

berbeza 40 dan 55 mm. Penyelidikan ini bertujuan untuk menyiasat kesan dua susun

atur pengkaku yang berbeza dari segi gerak balas struktur mereka berbanding dengan

dinding tidak berpengkukuh dengan mengutamakan perbezaan antara dinding

berpengkukuh perbezaan antara kait panca dan masonri terikat konvensional

menggunakan lapisan mortar. Dalam susun atur pertama pengkaku konkrit terkukuh

ditempatkan pada perimeter dinding di samping pengkaku melintang pada ketinggian

tengah dinding. Gerak balas struktur bagi panel yang diuji telah dipantau dari segi

keberkesanan dinding, ciri-ciri deformasi, pengurangan penyebaran terikan bagi

keupayaan dinding disebabkan kesan rekahan beban eksentrik dan mod kegagalan.

Keputusan ujian menunjukkan bahawa kehadiran pengkukuh telah menambah baik

tingkah laku panel yang diuji dengan menambah keupayaan membawa panel

terkukuh sebanyak 15% hingga 30% berbanding dengan specimen yang tidak

terkukuh. Tambahan pula pengkukuh yang terletak pada ketinggian tengah dinding

memainkan peranan penting dalam keupayaan dinding dan mod kegagalannya.

vii

ACKNOLDGEMENT

In The Name of ALLAH Most Gracious Most Merciful

It's my pleasure to express my deep thanks and gratitude to my Supervisor Assoc.

Prof. Dr Waleed A Thanoon, who introduce me to this field, for his valuable time of

discussion and supervision, my great thanks to Assoc. Prof. Ir. Dr. Mohd Saleh

Jafaar, Assoc. Prof. Ir. Dr. Mohd Razali A Kadir, and Assoc. Prof. Dr. Jamaluddin

Noorzae for their valuable time, direct supervision and discussion.

Many great thanks to structural laboratory staff for their valuable assistance,

especially Mr. Hadi for his assistance in producing of blocks, Mr. Halim for the

valuable time in helping fixing test set up.

I would like to express my deep gratitude to my parents' brother and sister for their

kind support

Finally ALLAH will bless all friends in UPM.

FARES

. . . V l l l

I certify that an Examination Committee met on 25" October 2005 to conduct the final examination of Fares A. Shehab on his Master of Science thesis entitled "Structural Behaviour of Interlocking Hollow Block Panel with Stiffener Subjected to Axial and Eccentric Load" in accordance with Universiti Pertanian Malaysia (Higher Degree) Act 1980 and Universiti Pertanian Malaysia (Higher Degree) Regulations 1981. The Committee recommends that the candidate be awarded the relevant degree. Members of the Examination Committee are as follows:

Ir. Salihudin Hassim, PhD Lecturer Faculty of Engineering Universiti Putra Malaysia (Chairman)

Abang Abdullah Abang Ali, PhD Professor Faculty of Engineering Universiti Putra Malaysia (Internal Examiner)

Thamer Ahmed Mohammed, PhD Associate Professor Faculty of Engineering Universiti Putra Malaysia (Internal Examiner)

Ir. Wan Hamidon Wan Badaruzzaman, PhD Professor Faculty of Engineering Universiti Kebangsaan Malaysia (External Examiner)

School of ~ r i d u i t e Studies Universiti Putra Malaysia

Date: 19 JAN 70fl6

This thesis submitted to Senate of Universiti Putra Malaysia and has been accepted as fulfilment of requirement for degree of Master of Science. The members of the supervisory Committee are as follows:

Waleed A. M. Thanoon, PhD Associate Professor Faculty of Engineering University Putra Malaysia (Chairman)

Mohd Saleh Jaafar, PhD Associate Professor Faculty of Engineering University Putra Malaysia (Member)

Mohd Razali A Kadir, PhD Associate Professor Faculty of Engineering University Putra Malaysia (Member)

Jamaluddin Noonae, PhD Associate Professor Faculty of Engineering University Putra Malaysia (Member)

AINI IDERIS, PhD Professor 1 Dean School of Graduate Studies Universiti Putra Malaysia

DECLARATION

I hereby declare that the thesis is based on my original work except for quotation and citation which have been duly acknowledged. I also declare that it has not been previously on concurrently submitted for any other degree at UPM or other institutions

TABLE OF CONTENTS

Page

DEDICATION ABSTRACT ABSTRAK ACKNOLEDGEMENTS APPROVAL DECLARATION LIST OF TABLES LIST OF FIGURES LIST OF ABBREVIATIONS

CHAPTER

INTRODUCTION General Problem Statement Scope and Objective Organization of Thesis

I1 LITERATURE REVIEW General Conventional Masonry System

Prism Test Axial Load Capacity Un-Reinforced Concrete Block Wall Structural Behavior of Return Walls Stiffened Hollow Block wall

Development of interlocking hollow block Concluding remarks

I11 METHODOLOGY of EXPERIMENTAL PROGRAM General Interlocking Hollow Block

Material Equipment

Experimental Program Testing of Individual Block Testing of Grouted Prisms Wall Panel

Description of wall panels Calculation of Load Carrying Capacity Construction Procedure

. . 11

iii vi . . . Vll l

ix xi xii xiii xvi

RESULTS and DISCUSSION Introduction Individual block strength Prism Test Structural Behavior of Interlocking Block Walls

Compressive Strength Deformation Characteristics Lateral Deflection Discussion on Lateral Deflection

of Interlocking Walls Vertical Deflection Discussion on Vertical Deformation

Load Strain Relation Discussion of Load Strain Relation Load Steel Strain Relation Failure Mode of Tested Panels Failure Mechanism

CONCLUSION Introduction Contribution of the Study Recommendation for Future Work

REFERENCES

APPENDICES

BIODATA OF THE AUTHOR

LIST OF TABLES

Table

3.1 The Physical Properties of Different Block Units Used in Construction

3.2 Tested Groups and their Groups Specimens

Efficiency Factors of Different Prism Specimen

Increase in Strength Compared to Un-stiffened Wall

Comparison between Bs Code Design Value and Ultimate Failure Load for Tested Specimens

xii

Page

LIST OF FIGURES

Figures

2.1 Load Eccentricity Relations

2.2 The Variation of Prism Strength with Grout Strength

2.3 Load Lateral Deformation for loft wall

2.4 Load Axial Deformation Curve for Axial Load Case.

2.5 Load Strain Relation for Tested Wall under Eccentric Load of t/3

2.6 Lateral Deflection of Tested Panels

2.7 Load Deflection Curve for loft (3m) Height Walls

2.8 Variation of Strain at Steel Reinforcement

2.9 Load Strain Relation for Tested Panels under Eccentric Load of t/3

2.10 Load Strain Relation for Tested Panels under Eccentric Load of tj;!

Relation between Ultimate Load and Grout Strength for One Course and Two Courses Bond Beam

2.12 Thallon Block System

2.13 Haener Block System

2.14 Block Unit Used by Abang

2.15 Mecano Block System

2.16 Block System Developed at Drexell University

2.17 WHD Wall Panel

2.18 Idealized Stress Strain Relations

2.19 Flexural Bending Test

Page

6

8

9

10

2.20 Different Types of Surfaces Investigated by Marzahn

2.2 1 Stress Strain Relations for Dry Stack and Conventional Masonry Developed by Marzahn

2.22 Compressive Strength Bed Quality Relation

2.23 Block System Developed by Mirsa

2.24 Anand and Ramamurthy Block System

2.25 Load Eccentricity Relation by Anand and Ramamurthy

2.26 Smart Block System

2.27 Comparison between Bounded and Unbounded Walls

2.28 Efficiency Eccentricity Relation for Different Slenderness Ratio

2.29 Failure of Selected Walls Tested by Amad

2.30 Axial Deformation of Un-Stiffened PUTRA block panel

2.3 1 The Profiles of Lateral Deformation along the Height of Tested Walls under Different Eccentricity of Applied Load

3.1 Three Types of Blocks

3.2 Different Parts of Block Factory in UPM

3.3 Block Unit in Testing program

3.4 Prism

3.5 Description of Wall Specimens along with Different Stiffeners Cross Sections

3.6 Casting of R.C. stiffener at bottom edge of the wall

3 -7 Wall Construction

Arrangement of Strain Gauges for Tested Groups

Test Set up

3.10 Boundary Condition at the Top and Bottom of Tested Wall

xiv

Boundary Condition at the Top and Bottom of Tested Wall

Axial Deforrnation Apparatus

Lateral Deformation Apparatus

Data Logger

Variation of Strength with Weight of Stretcher unit

Strength Weight Relation for Comer Block

Strength Weight Relation for Half Block

Failure of Individual Stretcher Block

Failure Mode of Interlocking Prisms

Efficiency Eccentricity Relation for Tested Putra Wall

Eccentricity Load Relation for Interlocking and Normal block wall

Lateral Deformation of Group A of panels

Lateral Deformation of group B of tested panels

Load Lateral Deformation for A3 and B2 Panel

Vertical Deformation for Group A

Load Vertical Deformation of Group B

Vertical Deformation of A,, BI and Un-stiffened Panel

Load Strain Relation for Al Panel

Load Strain Relation for A2 Panel

Load Strain Relation for A3 Panel

Load Strain Relation for BI Panel

Load Strain Relation for B2 Panel

4.19 Load Steel Strain Relation for Group A

Load Vertical Steel Strain Relation for Group B

Load Horizontal Steel Strain Relation

Failure of Wall A,

Failure of Panel A2

Failure of Panel A3

Failure of Panel B 1

Failure of Panel B2

Wall Cross Section

xvi

ABBREVIATION

is the compressive strength of masonry.

is the partial safety factor for masonry

is the width of masonry section

is the effective depth of masonry section

is the thickness of wall section

is the yield stress for steel reinforcement

is area of steel under compression

is area of steel under tension

is partial safety factor for steel reinforcement

is design axial load

is effective height

is cross section width

xvii

CHAPTER I

INTRODUCTION

General

Masonry is one of man's oldest building materials used in construction. Interlocking

hollow block is recently used in construction of non-load and load bearing walls. The

main concept of this new masonry system is the elimination of mortar layers in the

wall, and instead blocks are stacked to assemble the wall.

There is actually limited research on the behavior of interlocking wall systems which

is essential in order to compare the behavior of the interlocking wall systems to the

conventional masonry using mortar layer. This study highlights the structural

behavior of the stiffened interlocking hollow block walls in which the tested wall

panel is categorized into two groups; the first one is stiffened with perimeter stiffener

while second one stiffened with perimeter stiffener and mid height bond beam.

Problem Statement

Currently there is no standard available for the design of load bearing interlocking

block system. the structural behaviour and design parameters for this system are

expected to be different than the conventional load bearing wall system. This

research is mainly focused on the structural behavior of interlocking hollow block

walls with stiffeners constructed using PUTRA interlocking hollow block under

effect of axial and eccentric vertical load at the top of wall.

For load bearing walls the designer can provide stiffener in order to improve the

axial stiffness or lateral stiffness or the both for structure. (Mckenzie 2001)

Building codes state that situation should be avoided where damage to small area or

failure of single element could lead to collapse of major parts of the structure. The

provision of effective ties is necessary precaution to prevent progressive collapse.

The layout also must be such as to give a stable and robust structure. However there

are several types of ties as peripheral ties, internal ties, horizontal ties to column and

walls, and vertical ties. (Macgniley and Choo 1990)

Scope and Objective

The main scopes and objectives of this study are:

1) To investigate the structural behavior of interlocking hollow block wall

with stiffener under axial and eccentric loads.

2) To study the structural behavior for the two groups of tested panels in

which the first group is reinforced with perimeter stiffener and the second

one is reinforced with perimeter stiffeners and mid height horizontal

stiffener.

3) To study the effect of eccentricity in reducing the strength of tested

panels.

4) To investigate the failure mode of interlocking hollow block walls.

Organization of Thesis

The thesis is divided into five chapters; a brief description on the content of these

chapters is presented below:

Chapter One: highlights the definition of the problem along with the scope and

objectives of the study

Chapter Two: highlights the critical literature review on interlocking block and

traditional masonry.

The experimental program will be highlighted in Chapter Three, with all necessary

information regarding the specimens, boundary conditions, and method of test.

Chapter Four: The outcome of the results provides a clear picture about the strength

capacity and behavior of the tested specimens.

The reached conclusions along with the recommendations for future research are

highlighted in Chapter Five.

CHAPTER I1

LITERATURE REVIEW

General

The traditional method of masonry construction is a time consuming process due to

the presence of a large number of mortar joints. Early attempts were made to

increase the size of the masonry units (blocks instead of brick) thereby it would

reduce the number of mortar joints. The use of bedding mortar imposed constraints

on the number of layers to be constructed daily.

The need to accelerate the rate of construction led to the elimination of bedding

mortar and the development of non conventional methods in masonry construction,

interlocking block system was one of these developments. The elimination of

bedding mortar accelerates construction by reducing cost, and eliminates variations

results from workmanship and moisture penetration.

This chapter covers the structural behaviour of bonded masonry as well as

interlocking masonry system.

Conventional Masonry System

Prism Test

Drysdale and Hamid (1983) investigated the effect of void percentage and grout

strength on the behaviour of prism. The prism was half unit width (390 mm) three

courses high (5% mm) with thickness of 190 mm using eight however The

considered eccentricities were t/6, t/3 and 5t.112.

The result shows that the failure mode of the prism is not influenced by the

percentage of voids in the block, when the load was applied at eccentricity of 0 and - -= -- *---

t/6. At t/6 eccentricity, splitting tension failure occurred at the compression side of

grouted prisms. Tensile debonding of mortar at tension side was observed when the

load applied at higher eccentricity of tJ3 and 3/12. The failure started by the

development of crack along mortar joint followed by compression failure on

opposite side. The results show that the grout increases the ultimate capacity

particularly for small eccentricity of applied load.

Figure 2.1 shows that the eccentricity prism strength relation by using different types

of grout. Comparing the test results of the same eccentricity shows that even very

large changes in the quality of grout do not result in significant changes in relative