OLEH: FITRI HARDIYANTI MOCHAMAD YUSUF SANTOSO KONSEP TEGANGAN OLEH: FITRI HARDIYANTI MOCHAMAD YUSUF SANTOSO

Can the structure safely support the 30 kN load? Perform a static analysis to determine the internal force in each structural member and the reaction forces at the supports

Apakah cukup dengan statika saja ? Ternyata gaya Internal pada tiap bagian belum dapat menentukan sebuah struktur aman atau tidak. Kenapa? Apa parameter untuk dikatakan aman/ kuat atau tidak?

Apa yang terjadi pada benda yang dikenai gaya ?

Loads Stresses Equilibrium Equations Displacements Strains Strain-Displacement Equations Load-Deflection or Load-Stress Relations Stress-Strain

Apa stress (tegangan) itu. Apakah macamnya hanya satu saja Apa stress (tegangan) itu? Apakah macamnya hanya satu saja? Apakah hanya ada satu jenis beban (load) saja yang dapat menyebabkan stress ?

Untuk itu mari kita lihat secara umum gaya internal pada sebuah benda yang dikenai beberapa gaya eksternal

Internal Reactions Internal reactions are necessary to hold body together under loading. Method of sections - make a cut through body to find internal reactions at the point of the cut. Sambil lihat juga e-learning nya….

FBD After Cut Separate the two parts and draw a FBD of either side Use equations of equilibrium to relate the external loading to the internal reactions.

Definisi Tegangan Tegangan : Intensitas gaya internal pada sebuah bidang spesifik

Macam-Macam Tegangan

Coplanar Force System Start with internal system of forces as shown below to get proper signs for V, N and M. V

Sample Problem SOLUTION: Taking entire beam as free-body, calculate reactions at A and B. Determine equivalent internal force-couple systems at sections cut within segments AC, CD, and DB. Draw the shear and bending moment diagrams for the beam AB. The distributed load of 7200 N/m. extends over 0.3 m of the beam, from A to C, and the 1800 N load is applied at E. Plot results.

Sample Problem SOLUTION: Taking entire beam as a free-body, calculate reactions at A and B. Note: The 1800 N load at E may be replaced by a 1800 N force and 180 Nm. couple at D.

Sample Problem Evaluate equivalent internal force-couple systems at sections cut within segments AC, CD, and DB. From A to C: From C to D:

Sample Problem Evaluate equivalent internal force-couple systems at sections cut within segments AC, CD, and DB. From D to B:

Sample Problem Plot results. From A to C: From C to D: From D to B:

Definisi Tegangan Normal Tegangan normal adalah : Intensitas gaya internal yang bekerja tegak lurus terhadap bidang irisan Dimana : Tegangan normal Gaya yang bekerja tegak lurus terhadap irisan Luasan irisan

Tegangan Normal Rata-Rata b. Internal Force a. External Force c. Stress

Kenapa kok disebut tegangan normal rata-rata ? Figure: 01-13c

Jenis Tegangan Normal Figure: 01-15

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