Reinforced Concrete Mat Foundation Design

Seismic design philosophy for ductile precast concrete frames is discussed.

Reinforced concrete mat foundation design.

4 3 approximate plate analysis. Basic design criteria concentrically loaded d 2 all sides c critical section for two way shear b critical section for one way shear a critical section for flexure outside face of concrete column or. Nehrp seismic design technical brief no. A waterproof membrane sheet is placed over the ground surface and then 4 pcc is poured to create a level base for the mat raft foundation.

A mat foundation is a thick reinforced concrete slab supporting arrangements of columns or walls in a row or rows and transmitting the loads to the soil. Seismic design of reinforced concrete mat foundations has advanced significantly in the last twenty years. It is used to support storage tanks industrial equipment silos chimneys and various tower structures. It can model analyze and design any combination of two way mat raft slabs individual footings pile caps or grade beams.

Why mat is used. The method is generally applicable where columns are more or less equally spaced. For analysis the mat is divided into mutually perpendicular strips. As analytical capabilities have improved primarily in the form of finite element analysis the mathematical modeling of these continuous structural elements has led to seemingly more precise designs.

Where the differential settlement between columns will be small design the mat as reinforced concrete flat slab assuming planar soil pressure distribution. The slab is idealized as a mesh of rectangular plate finite elements with four nodes at the corners and three degrees of freedom dz rx and ry per node. A guide for practicing engineers published august 15 2012 author s ron klemencic ian mcfarlane neil hawkins. The difference between strong connection and ductile connection precast design is defined.

7 seismic design of reinforced concrete mat foundations. A discussion is presented.