premium finish quality or texture. Slip form method Slip forming is method of concrete placement whereby a moving form is used to create a continuous wall extrusion. This method is very efficient for well-suited structures, such as flanged and core wall systems. A very accurate wall thickness can be achieved but the surface is rough because of the abrasion of the form on the walls. Jump form method Jump forming, also known as climbing forming, is a method of construction whereby the walls are cast in discrete lifts. It is a stop-start process with day joints formed at each lift level. Similar to slip forming, jump forming is only efficient for structures with repetition of wall arrangement. Moreover, it is convenient for adding connections and extrusions at the floor level due to the discrete features. Nevertheless, the inclusion of day joints leaves higher chances for defects and imperfections. Tunnel form method Tunnel form construction uses a formwork system to cast slabs and walls as a single pour operation. It is suitable for cellular structures with regular repetition of both horizontal and vertical members. The advantage of this method is that the construction can progress vertically and horizontally at the same time, thereby increasing the integrity and stability of the structure. Nonplanar shear walls Due to functional requirements, the designer may choose non planar sections like C,L as opposed to the planar sections like rectangular/bar bell sections. Nonplanar sections require 3D analysis and are a research area. Modeling techniques Modeling techniques have been progressively updated during the last two decades, moving from linear static to nonlinear dynamic, enabling more realistic representation of global behavior, and different failure modes. Different modeling techniques shear walls span from macro models such as modified beam-column elements, to micro models such as 3D finite element models. An appropriate modeling technique should: Be capable of predicting the inelastic response Incorporating important materials characteristics Simulate behavioural feature: Lap splice and Bar Slip Represent the migration of the neutral axis Tension stiffening Interaction of flexure and shear actions Different models have been developed over time, including macro-models, vertical line element models, finite-element models, and multi-layer models. More recently, fiber-section beam-columns elements have become popular, as they can model most of the global response and failure modes properly, while avoiding sophistications associated with finite element models. Methods of analysis Finite element method Stringer panel model See also Hold down Earthquake