Analisa Inelastis Portal - Dinding Pengisi dengan “Equivalent Diagonal Strut”

Abstrak. Dinding pengisi biasa digunakan sebagai partisi atau penutup luar (cladding) pada struktur portal beton bertulang. Pemasangannya menunggu sampai struktur utama (portal beton bertulang) selesai dikerjakan, sehingga dianggap sebagai komponen non-struktur. Kenyataan menunjukkan, bila ada beban lateral yang besar (gempa), dinding pengisi memberi sumbangan yang besar terhadap kekakuan dan kekuatan struktur, sehingga perilaku keruntuhannya berbeda dibanding portal terbuka. Struktur yang direncanakan berperilaku sebagai portal terbuka daktail saat gempa, akibat dinding pengisi yang tidak merata dapat berubah menjadi struktur yang mempunyai mekanisme keruntuhan soft-storey yang berbahaya. Perilaku runtuh portal beton bertulang dengan dinding pengisi akibat beban lateral (gempa), rumit dan berperilaku non-linier. Perilaku tersebut sangat tergantung dari hubungan elemen portal dengan dinding pengisi sehingga sulit untuk memprediksinya dengan metoda analitis elastis biasa. Metoda Diagonal Tekan Ekivalen [Saneinejad dan Hobbs, 1995] memperhitungkan parameter non-linier dalam memodelkan struktur portal-isi agar “dinding pengisi” menjadi komponen struktur. Metode akan digunakan untuk analisis keruntuhan portal-isi dari eksperimen Universitas Colorado [Mehrabi et al, 1996]. Hasil analisis bersifat lower-bound dibandingkan hasil eksperimen, sehingga cocok untuk perencanaan. Parameter empiris pada metoda tersebut perlu dikaji lagi bila dipakai alat untuk menganalisis keruntuhan struktur portal-isi yang sebenarnya. Abstract. Masonry infill panels can be frequently found as interior and exterior partition in reinforced concrete (RC) structures. Since they are normally installed after the main structures (RC) finish and considered as architectural element so their presence is often ignored by engineers. But actually, they tend to interact with the bounding frame when the structure is subjected to strong earthquake load, and thus the collapsed behavior of infilled panels frame will be different against the open frame. In such situation while the infilled panels placed in un event location, such structures that have been design as ductile frame can be changed to be soft storey collapsed. The collapsed behaviors of reinforced concrete frame with infill panel due to lateral force from the earthquake are complicated and non linear. Their behavior is depending on the interaction between frame and infill panel so that it is difficult to predict using ordinary elastic methods. The Equivalent Diagonal Strut Method [Saneinejad and Hobbs, 1995] accounts for elastic and plastic behavior of infilled frames while they are considered as structural component. The method will be utilized to analyze the performance of RC frame masonry-infilled panels from University of Colorado [Mehrabi et al, 1996] that have been loaded until collapsed in their laboratory. The results values are rather lower-bound compared to the experiment and appropriate for design purposes. The empirical parameter taken in the method should be reviewed again if the method will be used as tools for the collapsed analysis of actual reinforced concrete infilled frames