BUILDING SCIENCE

Building Science



Building Science

Introduction

The purpose of the laboratory was to examine the deflections of the two properties of materials. The first property is the Young's modulus and the second property is the moment of inertia that is also termed as its geometry.

Young's Modulus is a measure of the stiffness of a material. It states how much a material will stretch (i.e., how much strain it will undergo) as a result of a given amount of stress. The formula for calculating it is:

The values for stress and strain must be taken at as low a stress level as possible, provided a difference in the length of the sample can be measured. Strain is unitless so Young's Modulus has the same units as stress, i.e. N/m² or Pa.

Method

For structures analysts, the two most important properties relating to stiffness are Young's modulus and moment of inertia, also known as material stiffness and geometric stiffness, respectively. Material stiffness measures the deflection of a sample by a given load per unit area. For example, because steel is stiffer than rubber, a rubber object deflects more than similarly shaped steel objects supporting the same load. Although one could design a rubber staircase without exceeding the rubber's ultimate strength, walking on the staircase would be like running through a funhouse[2]. The design would be acceptable from a stress and fatigue standpoint but unacceptable from a stiffness perspective.

Geometric stiffness comes into play because different geometries deflect differently under similar loads.

Young's Modulus (sometimes referred to as Modulus of Elasticity, meaning "measure" of elasticity) is an extremely important characteristic of a material. It is the numerical evaluation of Hooke's Law, namely the ratio of stress to strain (the measure of resistance to elastic deformation). To calculate Young's Modulus, stress (at any point) below the proportional limit is divided ...