Masonry structures behavior and design

transcript

Masonry structures Behavior and design

Ain Shams University Faculty of Engineering 4th year Structural Engineering Department Concrete Structures & Design Graduation Project

Outlines • Introduction & Historical background

• Advantage of masonry structures

• Most important properties of masonry materials

• Material Used on masonry structures

• Contemporary masonry structures

• Design of reinforced masonry beams

• Design loads

• Shear walls

• Failure of walls

• Out-of-plane loads

• Flexural behavior of loads

• Two way flexure

• Partially reinforced walls

Introduction&Historical background • Building Problems throughout history

• Idea of ancient masonry

• Most of Ancient masonry where loadbearing

• The most important and famous example throughout history is the pyramids

Introduction & Historical background

• Vaults and domes development and the great ingenuity to create pleasant buildings

• Development in gothic civilization

Advantage of masonry structures

•More economic

•Thermal and sound isolation

•Fire resistance

•Aesthetic value

•Durable qualities

Most important properties of masonry materials

• Compressive strength

• Modulus of elasticity

Provides complete info’s

on characteristics

Useful in design,

Researches

Most important properties of masonry materials

• Tensile strength: obtained from modulus of rupture test

• Initial rate of absorption (IRA): • KG/min / m2

• Durability: can be estimated using historic reports

• Efflorescence

Most common units

• Clay/shale units :

Concrete units :

Most common units

• Calcium silicate units :

stones :

Glass walls

Other used materials

• Mortar:

• Grout :

Reinforcement

• reinforced bars and joint reinforcement

Contemporary masonry • Reasons of masonry development

• Contemporary masonry elements

• Masonry building systems

• Types of masonry construction

walls columns Beams

Single storey

storey hybrid

Unreinforced Reinforced Prestressed

Masonry Beams

• Reinforced masonry beams and lintels are horizontal members used to span the openings in masonry walls.

• Bond beams are mostly located at floor and roof levels where their main function is: 1-To distribute vertical loads 2-To tie the elements of the building together

Design of beams

• T = As . Fy , C = ϒ1 Fm . β1 c b , ϒ1= β1 = 0.85

• For equilibrium with C = T , Therefor: 𝐜 =𝐀𝐬 𝐅𝐲

𝛄𝟏 𝐅𝐦 .𝛃𝟏 𝐛

Thus, the theoretical ultimate moment capacity can be calculated as:

𝐌𝐧 = 𝐓 𝐝 −𝛃𝟏 𝐜

𝟐 = 𝐀𝐬 𝐅𝐲 𝐝 −

𝐀𝐬 𝐅𝐲

𝟐𝛄𝟏 . 𝐅𝐦 . 𝐛

• Applying factor of safety in the form of capacity reduction factor

for flexure, so: 𝐌𝐮 ≤ 𝟎. 𝟖 𝐌𝐧 • Reinforcement(steel) ratio ρ = As/bd must be limited to avoid the

brittle failure and ensure some ductility.

Design loads

Seismic

Gravity

Shear wall

• Why we must add shear walls ?

• Its function?

Shear Walls

• In-plane and out-of-plane loads

• Comparison

Shear walls

• Walls with opening

Failure of walls

• Under lateral load and gravity load

Out-of-plane loads

• Types of out-of-plane loads

Permanent loads

Temporary loads

Flexural behavior of loads (single wythe)

• Vertical flexure

• Effect of superimposed axial load

Flexural behavior of loads (single wythe)

• Horizontal flexure

Two way flexure (single Wythe)

• Wall on three sides

Two way flexure (single Wythe)

• Wall on four sides

Partially reinforced walls

T hank you 2/2