Struktur Baja 1
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Transcript of Struktur Baja 1
Struktur Baja
Dimana saja struktur baja dipakai ?
Shanghai Sports Stadium
has a gross area of 170,000 m² (plan area 61,700 m²)
More than 4,000 tonnes of hollow sections and1,000 tonnes of steel plate were supplied to build the Shanghai Sports Stadium
Bird Nest Stadium
Sejarah Bangunan Baja Iron Bridge, England, 1779
Firth of Forth Bridge, Scotland, 1881
Eifel Tower, France , 1882
Empire State Building, USA, 1931
Akashi Kaikyo Bridge, Japan , 1998
Proses Pembuatan Baja
Definisi Baja
Steel is an alloy consisting mostly of iron, with a carbon content between 0.2 and 2.04% by weight, depending on grade. Carbon is the most cost-effective alloying material for iron, but various other alloying elements are used such as manganese, chromium, vanadium, and tungsten (wikipedia.org)
Jenis-jenis baja dikenal • Carbon steel, also called plain carbon steel, is steel where the
main alloying constituent is carbon; the other elements present are in quantities too small to affect the properties. The only other elements allowed in carbon steel are: manganese (1.65% max), silicon (0.60% max), and copper (0.60% max).
• Stainless steel is defined as a steel alloy with a minimum of 11.5% chromium content by mass. Stainless steel differs from carbon steel by amount of chromium present. Carbon steel rusts when exposed to air and moisture. This iron oxide film is active and accelerates corrosion by forming more iron oxide. Stainless steels have sufficient amount of chromium present so that a passive film of chromium oxide forms which prevents further corrosion.
• HSLA steel (high strength low alloy steel) is a type of steel alloy that provides many benefits over regular steel alloys. In general, HSLA alloys are much stronger and tougher than ordinary plain-carbon steels. They are used in cars, trucks, cranes, bridges, and other structures that are designed to handle large amounts of stress, often at very low temperatures.
Tujuan Kuliah Baja 1
Mahasiswa dapat merencanakan kekuatan penampang elemen struktur baja terhadap gaya aksial, lentur, geser dan kombinasinya.
Isi Kuliah Baja 1
Kuliah ini mempelajari perencanaan elemen-elemen struktur baja, yaitu batang tarik, batang tekan, balok, dan balok kolom dengan menggunakan metoda load and resistance factor design (LRFD)
Beban pada Struktur (Loads)
Secara garis besar dibagi :1. Dead Load permanent loads (gravity loads)
– the weight of structure self weight– nonstructural component floor covering, partition, and
suspended ceilings
2. Live Load not permanent loadStatic Load and dynamic loads
3. Wind Load4. Earthquake Loads
Building Codes, Design Specification
• Tata Cara Perencanaan Struktur baja untuk Bangunan Gedung (SNI 03-1729-2000)
• American Institute of Steel Construction (AISC, 1999)
Steel Characteristics
LL
Tensile Test
APf
The stress and strain can be computed as follows:
Where: f = axial tensile stressA = cross sectional area= axial strainL = length of specimen L = change in length
Ductility can be measured by the elongation, defined as:
100xLLL
eo
of
Where: e = elongation (%)Lf = length of the specimen at fracture
L0 = original length
Indealization of stress – strain curveFy = yield stress
Fu = the ultimate tensile strength
The ratio of stress to strain within the elastic range, denoted E and called Young’s modulus or modulus of elasticity (modulus elastisitas)
fE
E baja = 200000 MPa High Strength Steel
0.002
Standard Cross Sectional -Shapes
• Hot-rolled shapes
• Build up section
• Cold formed section
Concept in Structural Steel Design
Design Philosophies 1. Allowable Stress Design
required strength <= allowable strengh
- safety factor - Elastic design or working stress design- Service loads
2. Plastic Design - based on consideration of failure conditions.- Collapse mechanism, plastic hinge- Failure loads
3. Load and Resistance Factor Design (LRFD) - based on consideration of failure conditions- Load factors and factored strength
Factored load factored strength (loads x load factors) resistance x
resistance factor
ASD LRFD
Kombinasi beban DD + LD + (Lr or S or R)D + 0.75L + 0.75(Lr or S or R)D ± (0.6W or 0.7E)D + 0.75L + 0.75(0.6W) + 0.75(Lr or S or R)D + 0.75L±0.75(0.7E) + 0.75S0.6D±(0.6W or 0.7E)
Kombinasi beban 1.4D1.2D + 1.6L + 0.5(Lr or S or R)1.2D + 1.6(Lr or S or R) + (0.5L or 0.5W)1.2D +1.0W + 0.5L + 0.5(Lr or S or R)1.2D±1.0E + 0.5L + 0.2S0.9D ± (1.0W or 1.0E)
Load and Resistance Factors
nii RQ Where
Qi = a load effect ( a farce or a moment)
I = a load factor
Rn = the nominal resistance, or strength of the component under consideration
= resistance factor