FUNCTION OF STRUCTURETo support loads and transmit them to the ground.

Structure

Foundation

INTRODUCTION

WHAT IS A STRUCTURE ?A system consist of a series of connected parts.

Column (Kolom)

Slab (Plat lantai)

Beam (Balok)

Roof (atap)

STRUCTURAL FORMS1. Beam

For example, a beam may support a foot-path across a stream,

or... beam as a part of a large framework

Simple beam

Building frame

beam

As spans increase, the use of beams to support bridge decks becomes uneconomical. For moderately large spans, trusses may be used. Trusses carry loads by developing axial forces in their members, and their depth, for the same span and load, is larger than that of a beam but, because of the skeletal nature of their construction, will be lighter.

For example: the Warren truss shown is typical of thoseused in bridge construction; other geometries form roof supports and also carry bridge decks.

Truss

2. Truss

Berbagai bentuk struktur rangka

Portal frames are commonly used in building construction and generally comprise arrangements of beams and columns.

Portal

beam

kolom

rigid joint

3. Portal

Portal

The use of trusses to support bridge decks becomes impracticable for longer than moderate spans. In this Situation arches are often used.

Bridge Deck

Arch

Column

Bridge Deck

ArchHanger

4. Arches (lengkung)

For exceptionally long-span bridges, and sometimes for short spans, cables are used to support the bridge deck. Generally, the cables pass over saddles on the tops of towers and are fixed at each end within the ground by massive anchor blocks. The cables carry hangers from which the bridge deck is suspended

5. Cables (kabel)

Suspension bridge

Cable stayed bridge

SUPPORT SYSTEM

The loads applied to a structure are transferred to its foundations by its supports. In practice supports may be complex, in which case they are idealized into a form that may readily be analysed.

PIN SUPPORT (tumpuan sendi):Thus a support that: - allows rotation, but

- prevents translation

in practice: represented for analysis purposes by the idealized form:

Tumpuan sendi dapat menahan gaya horisontal dan vertikal,tetapi tidak dapat menahan momen.

TUMPUAN SENDI

RV

RH

ROLLER SUPPORT (tumpuan rol):

Thus a support that: - allows rotation, but - prevents translation in direction perpendi- cular to its bearing plate

in practice: represented for analysis purposes by the idealized form:

TUMPUAN ROL

Tumpuan rol hanya dapat menahan gaya tegak lurus pada bidang tumpunya, dan tidak dapat menahan momen

FIX SUPPORT (tumpuan jepit):

Thus a support that: - prevents translation and rotation in all directions

in practice: represented for analysis purposes by the idealized form:

Str. Baja

Str. Beton

STRUCTURAL ANALYSISSTRUCTURAL ANALYSISINTRODUCTION

TUMPUAN JEPIT

STRUCTURAL ANALYSISSTRUCTURAL ANALYSISINTRODUCTION

Resume:Support conditionsand itscharacteristics