uilding consruction and materials lecture 1.pptx

building consruction and materials

1. Building Construction & Materials

2. Understanding of Structure Architectural Structures in particular enclose and define a space in order to make it useful for a particular function. The utilitarian element differs structure from a sculpture. An enclosed surface may be built to serve for different purposes requiring different structures e.g. stadium, hospitals, malls etc. but main purpose of structure is to resist loads. A Structure is actually shaping certain materials and to use them in certain quantities that resist variety of loads acting on it. Structure is an essential component of architecture that allows a building to withstand against the pull of earth and other loads acting on it.

3. Type of Loads Acting on a Structure/ Building Loading conditions on same structure varies from time to time or may change rapidly with time. The most important loads carried by an architectural structure do not change abruptly. These are called STATIC LOADS. They are not evaluated case by case but are referred from codes, that code substitutes for an equivalent load that is derived on statistical evidences on given types of buildings so that under the worst circumstances floor will not fail. But it is not always sufficient to depend on these codes as responsibility for strength of the structure is not taken by the code authorities but with the architect. The types of loads acting on a buildings are Dead Load, Live Loads, Thermal & Settlement Loads and Dynamic Loads

4. Dead Load (DL) The load of the structure itself is dead load; it includes the load of structural system (walls , columns, beams, space frame) cladding material (interior & exterior), Slabs, partition walls and weight of other permanent service equipment HVAC or Plumbing). The dimension of a structural element depends essentially on the loads acting on It. The dead loads are easy to calculate, Weight is evaluated by consulting tables of Unit weights of structural material

5. Live Load (LL) All other loads acting on a structure other than dead loads of the structure is called live load. They include all the movable weights that include human, furniture & fixtures and other non structural elements such as rain, snow & ice. The wind pressure, water pressure or push of earth are also included in Live Load. Wind has become a very important load in recent years due to the extensive use of lighter materials and more efficient building techniques.  The wind load on building are difficult to ascertain to an accurate level; Average wind velocities are known to certain degree of Certainty. The impact of a hurricane winds on skyscraper may have to be found by means of aerodynamics tests on a model in a wind tunnel.

6. Thermal & Settlement Loads All building materials expand or contract with temperature change . Long continuous buildings will expand, and it is necessary to consider the expansion stresses. Expansion joints are provided at these points so that the structure is physically separated and can expand without causing structural damage . Another condition, producing equivalent effects as of high loads, stems from an un even settlement of the foundation of the building. The poor soli condition may reduce the support of the foundation. N additional load is applied to the building but due to uneven settlement, the supported portion of the building carries more load.

7. Dynamic Loads Load that change rapidly or applied suddenly are called dynamic loads. They are exceptionally dangerous if ignored. the magnitude of a load can be greatly increased by its dynamic effect . For e.g. driving a nail with hammer blow the more hard the blow is the greater the effect.